Qualification: 
Ph.D, MSc, B.Ed.
sreekalaco@am.amrita.edu

Dr. Sreekala currently serves as Assistant Professor (Sr. Gr)  at the Department of Physics, Amrita School of Arts and Sciences, Amritapuri. She was conferred with a Ph. D. in Physics from Amrita Vishwa Vidyapeetham in 2011. She plays a key role as Principal Investigators in some of the significant projects.

Education

Ph.D. (Physics) Amrita Vishwa Vidyapeetham 2011
SLET State Level Eligibility Test for Lectureship 1996
BEd (Physical Science) Kerala University, Thiruvananthapuram, 1stDiv 1995
M. Sc. (Physics) Kerala University, Thiruvananthapuram, 1stDiv 1994

Experience

Designation University Year
Assistant Professor Department of Physics Jan 11, 2016 to Present
Assistant Professor School of Biotechnology May 21, 2012 to Jan 10, 2016
Principal Investigator of Project Amrita Vishwa Vidyapeetham May 11, 2009 to May 10, 2012
Subject Matter Expert in Physics    VALUE @Amrita Nov 10, 2008 to December 2015
Lecturer School of Biotechnology, Amrita Vishwa Vidyapeetham Aug 5, 2006 to May 20, 2012
Lecturer Devaswom Board Pampa College, Parumala Nov 5, 2004 to Apr 30, 2006 
Lecturer Government Vocational HSS, Mavelikara Nov 26, 1999 to Oct 30, 2004
Lecturer NSS College, Pandalam July 19, 1998 to Nov 24, 1999

Projects

Sl.No Title Cost (in rupees) Duration Agency
1 Pedagogy Development in Engineering Physics 7 Lakhs 2013-2015 (Ongoing) ICT
2 Organic bulk heterojunction devices for photovoltaic solar cell applications 11.65226 Lakhs 2009-2012 (Completed) DST, Govt.of India

Research Experience

Summer Fellowship- Indian Academy of Science Summer Research Fellowship (SRF-2017) in National Physical Laboratory, New Delhi. May 19, 2017 to July 15, 2017
Research Scholar --- Organic bulk heterojunction devices for photovoltaic solar cell application, funded by Government of India, Department of Science and Technology (DST), New Delhi.
Funded by Government of India, Department of Science and Technology (DST), New Delhi
January 2008 to December 2011
Principle Investigator --- VALUE @ Amrita Physics Virtual Labs, Virtual and Accessible Laboratories Universalizing Education,
Funded by Government of India Ministry of Human Resource Development (MHRD)National Mission on Education Through Information and Communication Technology (NME-ICT) (No. F.5-29/2007-DL)
November 10, 2008 to Present

PhD STUDENTS

Sl.No Name of the Student Topic
1 Malini Prabhakaran Synthesis of Lead Salt based Nanostructures and Heteronano structures for Photo voltaic Applications
2 Ancy Albert (Full time) Ameliorating the room temperature stability of perovskite materials for solar cell application

Awards

  • Certificate of appreciation from Amrita Vishwa Vidyapeetham for the year 2011-2012, 2012-2013, 2013-2014, 2014-2015
  • Best Paper Presentation Award, in the ICMENS-2011 conference held at Kuala Lumpur Malaysia, during Nov 4th- 6th, 2011
  • Certificate of appreciation from Amrita Vishwa Vidyapeetham for the year 2010-2011
  • Certificate of appreciation from Amrita Vishwa Vidyapeetham for the year 2009-2010
  • Young Woman Scientist Award (2008) from Department of Science and technology (DST) through a project (SR/WOS-A/PS-04/2008)

INTEREST

  • Organic thin film sensors for radiation sensing and biosensing applications.
  • Thin film solar cells, Dye sensitized solar cells, Perovskite solar cells etc
  • Development of Micro electro mechanical systems (MEMS)
  • Microcontact printing of Biomolecules and Nanoelectronicsic
  • Microfludics and Biosensor
     

TEACHING

Publications

Publication Type: Conference Paper

Year of Publication Title

2020

V. R., Albert, A., and Dr. Sreekala C. O., “Electrochromic Properties of Vanadium Pentoxide Thin Film Prepared by Sol–Gel Process”, in ICT Systems and Sustainability, Singapore, 2020.[Abstract]


Prepared by chemical sol–gel process, thin films of\thinspace\textasciitilde500 nm thickness from the Vanadium pentoxide sol by spin coating over indium tin oxide (ITO) glass plates. These are annealed at different temperatures to identify the best sample. The field emission scanning electron microscopic (FESEM) analysis is used to view the morphology of the prepared film. The optical band gap of the film is evaluated from absorbance spectrum. For the prepared films, the transmittance study is also carried out. From the studies, it is inferred that the sample thin film annealed at 300 °C (S300) shows the best crystallinity and has lesser optical band gap of 2.16 eV. The electrochromic behaviour of the film is studied from cyclic voltammetric analysis. The reversible multichromism of yellow, green and blue is exhibited by the film annealed at 300 °C.

More »»

2017

A. Vasanth, Dr. Sreekala C. O., Sreelatha K. Sharma, and Jinchu, I., “Micro contact printed PEDOT: PSS as cathode in dye sensitized solar cells”, in 2017 International Conference on Technological Advancements in Power and Energy ( TAP Energy), Kollam, India, 2017.[Abstract]


The dye-sensitized solar cell (DSSC) is a solar cell which is mimicking the process of photosynthesis and converts the visible light into electricity. DSSC have begun as the third generation of photovoltaic devices, which offers advantages, including judicious light to photon conversion efficiency, low cost, flexible and easy fabrication. In this work we made photo cathode by printing PEDOT:PSS on FTO glass plate by the method of micro contact printing using a Polydimethylsiloxane (PDMS) stamp replicated from compact disc. The PDMS stamp is analyzed using AFM. The thickness and transmittance of the printed photo cathode is studied. DSSC is made with Alizarine Red as the sensitizing Dye. The photovoltaic parameters of the device are analysed. It is found that the microcontact printing can also be used as an effective technology to fabricate solar cells.

More »»

2017

S. V. Krishnan, Dr. Sreekala C. O., and Prabhakaran, M., “Fabrication of micro fluidic channels for functionalizing lead selenide quantum dots for photovoltaic application”, in 2017 International Conference on Technological Advancements in Power and Energy ( TAP Energy), 2017.[Abstract]


Microfluidic devices can be used for variety of applications. Fluid mixing, chemical reactions in small volumes are some of them. Micro fluidic channels are mainly used in biochemical analysis. There are many benefits in using these channels, such as decreased manufacture cost, reduced time of analysis. In this work soft lithographic technique is used for the fabrication of the micro fluidic channels. Using this micro fluidic channels we coated (capping) L-cysteine over Lead selenide quantum dots (PbSe QD's). Conducted assay and nitro prusside test to analyze the structure of the L-Cystein capped QDs. These L-Cystein capped QDs can found application in photovoltaics.

More »»

2017

Dr. Sreekala C. O., Pragash, R., Sreelatha K. Sharma, and Jinchu, I., “Influence of film thickness of photoanode on dye sensitized solar cell performance”, in 2017 International Conference on Technological Advancements in Power and Energy ( TAP Energy), 2017.[Abstract]


Solar energy is a potential candidate to fulfill the rapidly increasing energy demands of future generation. Owing to this increasing demand, high efficiency solar cells stand an area of intense research. Dye Sensitized Solar Cells have attracted lot of recognition and is considered as a promising upcoming technology, which can compete with silicon based solar cells, owing to its intrinsic cost reduction potential, relatively modest production technology and its versatility. The efficiency parameter of a cell is governed by the adsorption of dye molecules, which depends on the thickness of the semiconducting layer. This paper emphasizes on the effect of thickness of the TiO2 layer of DSSC on its conversion efficiency by means of spin coating and Doctor blade techniques. The photo voltaic parameters were studied and compared with the thickness of the fabricated devices, measured using ellipsometry. It is found that the device fabricated using spin coating technique with single layer have relatively higher efficiency (about 2.53 %). This work enabled us to know the role of thickness in the efficiency of DSSC.

More »»

2016

N. Ajayakumar, Dr. Sreekala C. O., Tom, A. E., Thomas, A., and Ison, V. V., “Heterojunction TiO2/PbS quantum dot solar cells”, in 2016 International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT), Chennai, India, 2016.[Abstract]


PbS Quantum dots are promising materials for photovoltaic applications due to their absorption in the NIR region. In this work monodisperse lead sulfide quantum dots are synthesized using colloidal procedures using oleic acid and oleylamine as the stabilizing agents and 1-octadecene as the non-coordinating solvent. Heterojunction solar cell with FTO/TiO2/PbS/Au structure is fabricated and characterized. The current-voltage characteristics shows the roll-over effect that refers to the saturation of photocurrent in forward bias and crossover effect which occurs when the light and dark J-V curves intersect.

More »»

2016

A. George, Thanseema, A. P., Sreelatha K. Sharma, Dr. Sreekala C. O., and Jinchu, I., “Device stability study of dye sensitized solar cells incorporated with MWCNTs”, in 2016 International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT), Chennai, India, 2016.[Abstract]


Dye-sensitized solar cells (DSSC) or Gratzel cells have attracted extensive academic and commercial interest during the last 20 years due to their potential for low cost solar energy conversion. Dye-sensitized solar cell works on the principle similar to photosynthesis. The major parts of dye-sensitized solar cells are working electrode or photo electrode, dye, electrolyte and counter electrode. Each key components have its own importance for the conversion visible light into electricity. This work highlights studies on stability of device fabricated with different counter electrodes. The photovoltaic parameters of the prepared DSSCs were compared and tabulated. It is found that the DSSC with functionalized MWCNTs as counter electrode shows the best efficiency.

More »»

2016

S. Mohan, Dr. Sreekala C. O., Tom, A. E., Thomas, A., and Ison, V. V., “Photovoltaic studies of PbSe quantum dot based solar cells”, in 2016 International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT), Chennai, India, 2016.[Abstract]


The PbSe quantum dots are synthesized by organometallic synthesis method. The current-voltage (J-V) characteristics of TiO2/PbSe quantum dot (QD) solar cells from a Schottky junction that forms at the back metal electrode opposing the desirable diode formed between the TiO2 and PbSe QD layers. We study the J-V curves of the FTO/TiO2/PbSe/Au device under dark and illuminated condition. The FESEM image of the device cross section is taken and analyzed. We also study the band structure of the device.

More »»

2016

M. Prabhakaran, Dr. Sreekala C. O., Tom, A. E., Thomas, A., and Ison, V. V., “Synthesis and characterization of Lead Selenide quantum dots for photovoltaic application”, in 2016 International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT), 2016.[Abstract]


Lead Selenide (PbSe) quantum dots (QDs) with absorption in the NIR region are synthesized in a non-coordinating solvent, octadecene by organometallic synthesis procedure. The high resolution transmission electron microscopy (HRTEM) analysis demonstrated spherical shape and monodispered nature of PbSe Quantum dots. Absorption spectrum demonstrates that the QDs show absorbance in the near infrared (NIR) region. The synthesized QDs give a good dispersion in n-hexane. More »»

2016

I. Jinchu, Krishnan, B., Dr. Sreekala C. O., Balakrishnan, N., Sajeev, U. S., and Sreelatha, K. S., “Escalating the performance of perovskite solar cell via electrospun TiO2 nanofibers”, in 2016 International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT), 2016.[Abstract]


A Perovskite solar cell is a type of solar cell which includes a perovskite structured compound, most commonly a hybrid organic-inorganic lead or tin halide based material, as the light harvesting active layer. In this work solar cell based on titanium dioxide (TiO2) thin film, sensitized with methyl ammonium lead iodide (CH3NH3PbI3) perovskite are prepared. Thin films were grown on fluorine doped tin oxide (FTO) glass plate. TiO2 is working as the anode and a noble metal will work as the cathode. A perovskite is more efficient than a dye in sensitizing a solar cell. It will act both as hole transporting material and sensitizer. It is found that the efficiency of solar cell devices using these materials shows considerable change in Voc and Jsc by the use of TiO2 nanofibers as the anode material. More »»

2016

I. Jinchu, Dr. Sreekala C. O., Sreelatha K. Sharma, and Mohan, R. E., “Photovoltaic parameters of DSSCs using natural dyes with TiO2 nanopowder and nanofiber as photoanodes: A comparative study”, in 2016 International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT), Chennai, India, 2016.[Abstract]


Dye-sensitized solar cells (DSCs) are currently attracting academic and commercial interest as regenerative low-cost alternatives to conventional solar cell devices. Researchers are focusing to facilitate for producing a low cost, eco-friendly and more efficient dye sensitized solar cells. Natural dye sensitized solar cells are a promising class of photovoltaic cells with the capacity of generating green energy at low production cost since no expensive equipment is required in their fabrication. In the present work we discuss the effect of Photoanodes sensitized with natural dyes Lawsone and Alizarin. We compared the efficiency of the devices fabricated with TiO2 nanofibers and nanopowder as photoanodes using these natural dyes. It is found that when we used nano fibers instead of nano powder as photo anode the dye adsorption on the TiO2 surface increases. This helps to harvest more photons and increases photocurrent density. As a result there is a significant increase in short circuit current density and conversion efficiency.

More »»

2016

A. Ramachandran, Jinchu, I., and Dr. Sreekala C. O., “Studies on polymer based counter electrodes for DSSC application”, in 2016 International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT), Chennai, India, 2016.[Abstract]


Dye-sensitized solar cell provides a precisely and economically reliable alternate concept of present day energy crisis. DSSC have emerged as the next generation of photovoltaic devices, offering several advantages, including moderate light to conversion efficiency, low cost, flexible and easy fabrication. DSSC have many components that have to be optimized, are a mesoporous titania layer adsorbed with dye molecule, electrolyte and a counter electrode. In this work we focused on making polymer based counter electrodes for DSSC application. We made counter electrodes with PEDOT:PSS incorporated with MWCNTs and compared with the standard platinum counter electrode. The optical transmittance of the counter electrodes is studied to examine their possibility for use as transparent counter electrodes for DSSC application.

More »»

2014

Dr. Krishnashree Achuthan, S., F., Prema Nedungadi, Raghu Raman, l., B., Dr. Sreekala C. O., and Sreelatha, K. S., “Improving Perception of Invisible Phenomena in UG Physics Education Using ICT”, in International Conference on Information and Communication Technology (IEEE Xplore), 2014.[Abstract]


Experimental learning plays paramount role in Physics education. Experimental physics requires phenomenological investigations in several cases and this includes understanding visible and invisible heuristic procedures to discern underlying concepts. This study investigates the invisible yet evident occurrences of physical phenomena that are difficult to grasp from a learner's perspective. In this work the contribution of compounded effects of using computational techniques, multimedia enhanced simulations and interactive animations to draw the learner's attention to those physically undiscernable aspects of physics experiments is presented. The study has investigated three physics experiments by engineering students (N= 42) and the methodology focused on differentiating the learning outcomes between classroom teaching, laboratory experimentation and virtual laboratories. The students were divided into two batches. Visual and conceptual understanding was quantified by assessments that included their visual and conceptual understanding. Our study not only revealed severe limitations in learning invisible phenomena based on traditional classroom methods but also empirically validated the positive impact on learning outcomes when the classroom method is combined with Virtual Labs approach.

More »»
PDF iconimproving-perception-of-invisible-phenomena-in-ug-physics-education-using-ict.pdf

2011

Dr. Sreekala C. O., Sreelatha, K. S., and Roy, M. S., “Hybrid Bulk Heterojunction Solar Cells based on Metal Phthalocyanines”, in National Seminar on Trends in Physical Sciences (TriPS-2011), SreeSankara College, Kalady, Kerala, 2011.

2011

Dr. Krishnashree Achuthan, Sreelatha K. Sharma, S. Surendran, Dr. Shyam Diwakar, Prof. Prema Nedungadi, S. Humphreys, Dr. Sreekala C. O., Dr. Zeena S. Pillai, Raghu Raman, A. Deepthi, Rathish Gangadharan, Dr. Saritha A., Jyothi Ranganatha, Sreedha Sambhudevan, and Suma Mahesh, “The VALUE @ Amrita Virtual Labs Project: Using Web Technology to Provide Virtual Laboratory Access to Students”, in Global Humanitarian Technology Conference (GHTC), 2011 IEEE, 2011, pp. 117-121.[Abstract]


In response to the Indian Ministry of Human Resource Development (MHRD) National Mission on Education through Information and Communication Technology (NME-ICT) Initiative, the Virtual and Accessible Laboratories Universalizing Education (VALUE @ Amrita) Virtual Labs Project was initiated to provide laboratory-learning experiences to college and university students across India who may not have access to adequate laboratory facilities or equipment. These virtual laboratories require only a broadband Internet connection and standard web browser. Amrita Vishwa Vidyapeetham University is part of a consortium of twelve institutions building over two hundred virtual labs covering nine key disciplines in science and engineering. This National Mission project hopes to reach out to India's millions of engineering and science students at both undergraduate and postgraduate levels. The Virtual Labs Project is providing virtual laboratory experiments that directly support the All India Council for Technical Education (AICTE) and the University Grants Commission (UGC) model curricula for engineering and sciences undergraduate and postgraduate programs.

More »»
PDF iconthe-value-amrita-virtual-lab-project-using-web-technology-to-provide-virtual-laboratory-access-to-students.pdf

2010

Y. Janu, Roy, M. S., Dr. Sreekala C. O., and K .S.Sreelatha, “Enhancement of Photovoltaic Properties by the Surface Treatment of Nanostructured TiO2 in DSSCs using Curcumin Dye as Sensitizer”, in International Conference on Photochemical Conversion on Solar Energy (icpse-2010), Amrita Vishwa Vidyapeetham, Coimbatore, 2010.

2010

Dr. Sreekala C. O., Sreelatha, K. S., and Roy, M. S., “Electrical and Optical Studies of Bulk Hetrojunction Device Based on CuPc and ZnS”, in International conference on Materials for the Millennium (MatCon 2010), University of Science and technology, Kochi, Kerala, 2010.

2010

K. B. S. Pavan Kumar, Sreelatha, K. S., .S.Roy, M., and Dr. Sreekala C. O., “Improvement in Conversion Efficiency of Dye-sensitized Solar Cells Using Functionalized Multi-wall Carbon Nanotubes in the TiO2 Sensitization Process”, in International Conference in nanotechnology for Sustainable Energy-2010, organized by European Science Foundation (ESF), Innsbruck, Austria, 2010.

2008

Dr. Sreekala C. O., Balraju, P., Deol, Y. S., Pradeep, P., and Roy, M. S., “Photo Response in Zinc Oxide Doped Alizarin Thin Film”, in Thermophysical Properties of Materials and Devices: IVth National Conference on Thermophysical Properties-NCTP'07, 2008.[Abstract]


Hybrid structure based on organic and inorganic materials are emerging as most promising materials for photovoltaic applications. We have designed a hybrid structurc based on Alizarin (1, 2 dihydroxy anthraquinone) and a wide band gap zinc oxide. Alizarin acts as donor and zinc oxide acts as an acceptor material. The device having configuration of ITO/Aln:ZnO/Ag was characterized by analyzing its optical and electrical characteristics. It is found that the doping with zinc oxide imparts an accelerated improvement in device performance particularly in terms of its photo response. Impedance analysis of the device was carried out by recording Cole‐Cole plot in between real and imaginary impedance under biasing varying from 0 to 5 V.

More »»

Publication Type: Journal Article

Year of Publication Title

2020

A. S. Sarma, Dr. Sreekala C. O., and Dr. Sreedevi K Menon, “Microstrip fed monopole antenna on Barium Titanate-PDMS substrate”, Materials Today: Proceedings, 2020.[Abstract]


Barium Titanate (BaTiO3)-Polydimethylsiloxane (PDMS) composite is used to realise a flexible substrate for a microstrip fed monopole antenna. The antenna radiation and reflection characteristics are studied. The monopole parameters and ground plane are analysed for the best performance of the antenna. The antenna optimized by simulation is validated by measurement. The antenna is found to be an effective radiator and can be used for different wireless communication applications.

More »»

2020

A. Sekhar, Albert, A., Jinchu, I., Sreelatha K. Sharma, and Dr. Sreekala C. O., “Optimisation of electrochromic properties of titanium doped V2O5 film”, Materials Today: Proceedings, 2020.[Abstract]


V2O5 is a versatile material that have controllable transmission, absorption and reflectance that are suitable for electrochromic applications. In this report, the Vanadium pentoxide is modified by doping with titanium using its propoxide precursors. Thin films were fabricated over Florine doped Tin Oxide (FTO) coated glass plate by spin coating technique. Electrochromic properties of V2O5 film is improved by doping with Titanium. X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM) analysis and UV Visible absorption and transmission of the prepared films were taken. To study the electromagnetic properties of the thin films, they were annealed at different temperatures for 30 min. Temperature dependence on optical properties of Ti-V2O5 films were analysed by absorbance and transmittance spectrum. We optimised the fabricated films for its electrochromic properties at temperatures of 350 °C, 450 °C and 550 °C. Among this the thin film annealed at 450 °C shows better oxidation and reduction peaks. Thus the electrochemical behaviour of thin films (V2O5 doped with Titanium) were studied by the cyclic voltammeter.

More »»

2020

I. Jinchu, Dr. Sreekala C. O., and Sreelatha K. Sharma, “Lawsone metal complex as an effective sensitizer for dye sensitized solar cells”, Materials Today: Proceedings, 2020.[Abstract]


Dye sensitized solar cells (DSSCs) using natural dyes are found to have moderate efficiency of energy conversion. In this work we address the energy conversion efficiency and stability of the DSSCs sensitized with natural dye namely Lawsone. Anchoring of the dye with the titanium dioxide is one of the factors which decides the efficiency and stability of the fabricated device. Lawsone ligand is synthesized first and then different metal complexes of Manganese, Zinc, Nickel, Cobalt, Copper, Iron and Chromium are attached to this ligand. DSSC’s are fabricated by sensitizing the titanium dioxide (TiO2) nano powder and nano fiber with the prepared Lawsone metal complex dyes. The device sensitized with Lawsone chromium metal complex shows increased efficiency and stability than the other DSSCs using simple natural dyes.

More »»

2020

R. Chandran, Dr. Sreekala C. O., and Dr. Sreedevi K Menon, “BaTiO3/V2O5 composite based cylindrical dielectric resonator antenna for X-band applications”, Materials Today: Proceedings, 2020.[Abstract]


This paper presents the use of a Cylindrical Dielectric Resonator fabricated using Barium Titanate/Vanadium Pentoxide (BaTiO3/V2O5) composite material as antenna. The dielectric constant of the cylindrical pellet is measured to be 49.3. The dielectric resonator has a diameter of 14 mm and height of 1.17 mm. The resonator is energized with a 50 Ω microstrip line etched on FR4 epoxy performing as a Cylindrical Dielectric Resonator Antenna (CDRA). The antenna is found to radiate at a frequency of 9.5 GHz with an impedance bandwidth of 226 MHz. The fabricated CDRA shows good reflection and radiation characteristics with a high gain of 8.22dBi at the resonant frequency. The radiation pattern shows that the proposed antenna has good directivity with reduced back lobes. The proposed antenna can be used for weather monitoring, air traffic control, defense tracking and also in space communications.

More »»

2020

Baby Sreeja S. D., Dr. Sundararaman Gopalan, and Dr. Sreekala C. O., “Piezoelectric studies of PEDOT:PSS incorporated BaTiO3/ PDMS micro-generator”, Materials Today: Proceedings, 2020.[Abstract]


Different naturally occurring and wasted vibrational energy forms can be converted into electrical output with the help of proper Piezoelectric Energy Harvesting Systems (PEHS). Even though there are many attractive features of piezoelectric materials like: high energy density, light weight, compactness, the one main disadvantage is low current density. In this work flexible piezoelectric micro-generators suitable for PEHS were made with simple, low cost hydrothermal method with BaTiO3/PDMS micro-composites. The ceramic polymer micro-composite was developed by mixing of Barium Titanate (BaTiO3) ceramic powder with polydimethylsiloxane (PDMS) polymer in 4:1 wt ratio. The fabricated device is flexible, heat resistant and stretchable with good output voltages upon the application of vibrational energy. The short circuit current is found to be improved by incorporating 0.01 wt% of poly (3,4-ethylenedioxythiophene) poly (styrenesulfonic acid)(PEDOT: PSS) to the BaTiO3/PDMS composite material. The Piezo electric characteristics of both materials are compared and the PEDOT: PSS incorporated material is found to have better output current density. The newly developed micro-generator has improved piezoelectric characteristics.

More »»

2020

P. S. Lekshmi, Albert, A., Jinchu, I., and Dr. Sreekala C. O., “Energy storage application of titanium doped vanadium pentoxide nanostructures prepared by electrospinning method”, Materials Today: Proceedings, 2020.[Abstract]


<p>Vanadium pentoxide is the widely using transition metal oxide which has applications in areas of electrochromic devices, Li ions batteries, super capacitors, photovoltaic and optical devices. Doped vanadium pentoxide shows better stability and higher transmittance than pure vanadium pentoxide. Vanadium pentoxide nanostructures show better potential in cyclic voltammetry. Here we prepared Titanium doped vanadium pentoxide using Titanium tetra isopropoxide and vanadium (V) triisopropoxide oxide. The prepared solution was mixed with Polyvinylpyrrolidone (PVP) and the nanostructures were formed by electrospinning method. The formed nanostructures were annealed at different temperatures 350 °C, 450 °C and 550 °C. The annealed films were characterized by SEM and XRD methods. The cyclic voltammetry analysis was done to analyze its use in Lithium-ion batteries. The thin film annealed at 450 °C shows the best performance.</p>

More »»

2019

S. Suhailrashid, Dr. Sreekala C. O., and Dr. Sreedevi K Menon, “Dielectric Resonator Antenna on Ba TiO3 embedded with TiO2 Nano composite for Wi-Fi applications”, IOP Conference Series: Materials Science and Engineering, vol. 577, p. 012190, 2019.[Abstract]


A cylindrical dielectric resonator antenna (DRA) energized using microstrip line for Wi-Fi applications is discussed in this paper. The cylindrical DRA of 14mm diameter and 2mm height are fabricated using titanium dioxide (TiO2) nanoparticle embedded in high dielectric constant barium titanate (BaTiO3) material. It is found that the BaTiO3: TiO2 composite is very effective as a radiator. The fabricated DRA radiates in Wi-Fi frequency of 5.5 GHz with good reflection and radiation performance.

More »»

2019

A. Anil, Sreedha Sambhudevan, Dr. Sreekala C. O., and Balakrishnan Shankar, “Effect of silver nanoparticle in the PEDOT: PSS counter electrode of dye sensitized solar cell”, AIP Conference Proceedings, 2019.[Abstract]


In this study, a conducting polymer PEDOT: PSS counter electrode is introduced in a typical DSSC (Dye Sensitized Solar Cell) with N719 dye adsorbed TiO2 nanoparticle coated FTO (Flourine doped Tin Oxide) glass as photo anode and an iodide-triiodide system as electrolyte. Counter electrode modification is done by introducing silver nano particles (NPs) along with PEDOT:PSS to heighten the performance of DSSCs. Five unlike counter electrodes are made by PEDOT: PSS, PEDOT:PSS+ 25wt% Ag np, PEDOT:PSS+ 50wt% Ag np, PEDOT:PSS+ 75wt% Ag np, PEDOT:PSS+ 100wt% Ag nanoparticles respectively,DSSCs are fabricated, photovoltaic parameters are measured and related with the standard platinum counter electrode. Themorphology of the counter electrodes is studied by FESEM analysis. The thickness of different photo cathodes is studied by ellipsometry. It is found that as the weight% of Silver nanoparticle is increasing the efficiency of the device is also increasing. The photovoltaic conversion efficiency of the device with PEDOT:PSS+75wt%Agnp is giving 3.75% efficiency. But for PEDOT: PSS+ 100wt% Agnp, the efficiency decreases to 3.05%. This is because as the weight percentage of silver nanoparticle increases, due to its metallic nature, it acts as a hole trapping material than the hole conducting material.

More »»

2018

A. Ramachandran, Dr. Sreekala C. O., Sreelatha K. Sharma, and Jinchu, I., “Photovoltaic studies of Dye Sensitized Solar cells Fabricated from Microwave Exposed Photo anodes”, IOP Conference Series: Materials Science and Engineering, vol. 310, p. 012151, 2018.[Abstract]


The configuration of Dye Sensitized solar cells (DSSC), consists of sintered nanoparticle titanium dioxide film, dyes, electrolyte and counter electrodes. Upon the absorption of photons by the dye molecules, excitons are generated, subsequently electrons are injected into the TiO2 photoanode. Afterward the electrons injected into the TiO2 photoanode, to produce photocurrent, scavenged by redox couple, and the hole transport to the photo cathode. The power conversion efficiency of the device depends on the amount of dye adsorbed by the photoanode. This paper explores in enhancing the efficiency of the device by controlled microwave exposure. With same exposure time, the photoanode is exposed at three different frequencies. SEM analysis is carried out to find the porosity of the photoanode on exposure. Current density is found to have an effect on microwave exposure.

More »»

2018

K. E. Swathi, Jinchu, I., Sreelatha K. Sharma, Dr. Sreekala C. O., and Dr. Sreedevi K Menon, “Effect of microwave exposure on the photo anode of DSSC sensitized with natural dye”, IOP Conference Series: Materials Science and Engineering, vol. 310, p. 012141, 2018.[Abstract]


Dye Sensitized solar cells (DSSC) are also referred to as dye sensitised cells (DSC) or Graetzel cell are the device that converts solar energy in to electricity by the photovoltaic effect. This is the class of advanced cell that mimics the artificial photosynthesis. DSSC fabrication is simple and can be done using readily available low cost materials that are nontoxic, environment friendly and works even under low flux of sunlight. DSSC exhibits good efficiency of 10-14 %. This paper emphasis on the study of enhancing the efficiency of DSSC by exposing the photo anode to microwave frequency. Effect of duration of microwave exposure at 2.6 GHz on energy efficiency of solar cell is studied in detail. The SEM analysis and dye desorption studies of the photo anode confirms an increased solar energy conversion efficiency of the DSSC.

More »»

2018

A. B. Sreebha, Suresh, S., Dr. Sreekala C. O., and Pillai, V. P. Mahadevan, “Volume holographic gratings in acrylamide-based photopolymer to provide selective light as an added input for improving the performance of dye-sensitized solar cells”, CURRENT SCIENCE, vol. 114, no. 11, p. 2267, 2018.[Abstract]


A transmission holographic grating with good storage life and diffraction efficiency is fabricated in an indigenously prepared red-sensitive photopolymer. Stability retained by the photopolymer transmission holographic grating in its diffraction efficiency upon long-term exposure to temperature indicates the suitability of the fabricated photopolymer holograms in solar applications. Holographic elements diffract different wavelengths to different regions and dye sensitized solar cells (DSSCs) can absorb the desired range of wavelengths from the diffracted light. Hence, we exploit this property of the holographic grating to enrich the performance of DSSCs by enhancing its input and output power, particularly under low photometric conditions. Improvement in maximum power output of DSSCs is observed in all cases, with a maximum enhancement of about 100% for the lowest level of input intensity.

More »»

2016

J. I, R, J., N. Pandurangan, Sreelatha K. Sharma, K. Achuthan, and Dr. Sreekala C. O., “Anthraquinones A Probe to Enhance The Photovoltaic Properties of DSSCs ”, International Journal of Electrical and Computer Engineering (IJECE) , 2016.[Abstract]


Natural dye sensitized solar cells are a promising class of photovoltaic cells with the capacity of generating green energy at low production cost since no expensive equipment is required in their fabrication. Photovoltaics are a precious technology in the hasty world where energy prices are goes on increasing within seconds. Researchers are focusing to facilitate for producing eco-friendly, low cost and more efficient dye sensitized solar cells. In the present work we discuss the comparative photovoltaic studies of Lawsone, a natural dye from henna plant and Alizarin, a natural dye from the root of madder for fabricating the Dye sensitized solar cells (DSSCs). The absorption spectrum of Lawsone and Alizarin is found to be shifted to the longer wavelength region after the complex formation. As a result there is a significant increase in short circuit current density and conversion efficiency. This result is compared with the standard dye i.e. N719 dye.

More »»

2016

S. Suresh, Deepak, T. Gangadhara, Ni, C., Dr. Sreekala C. O., Satyanarayana, M., A. Nair, S., and Pillai, V. Pappukkuty, “The Role Of Crystallinity Of The Nb2O5 Blocking Layer On The Performance Of Dye-Sensitized Solar”, New Journal of Chemistry, vol. 40, 7 vol., pp. 6228-6237, 2016.[Abstract]


The prevention of back electron transfer by inserting an energy barrier layer at the interface of a photo-anode is an effective method for improving the photovoltaic parameters in dye sensitised solar cells (DSSCs). In this study, phase a modified Nb2O5 blocking layer was inserted at the fluorine doped tin oxide (FTO)/TiO2 interface via a Rf magnetron sputtering process. For a critical tunnelling distance of ∼40 nm, the crystalline Nb2O5 blocking layer improved the efficiency close to 7% and outperformed the amorphous blocking layer by about 68%. The longer electron lifetime observed in DSSCs containing an inhomogeneous Nb2O5 layer indicates that trapping/de-trapping impedes the discharge of electrons to the TiO2 band edge. The origin of the longer electron lifetime is explained by formulating a theory from photovoltage decay measurements.

More »»

2016

A. JS, NP, S., S, S., KP, V., ,, Prabhakaran, M., Isonc, V. V., and Dr. Sreekala C. O., “Surface Modified Lead Sulphide Quantum Dots For In Vitro Imaging Of Breast Cancer Cells Adopting Confocal Raman Spectroscopy”, International Journal of Chemical Sciences, vol. 14, 4 vol., 2016.[Abstract]


Nanoparticles are potentially used for early cancer detection, accurate diagnosis, and cancer treatment. Due to their small direct band gap and large excitation Bohr radius, lead sulphide quantum dots are important semiconductor material. The red shifted emission band, coupled with the small particle size, is facilitating clearance of imaging. Lead sulphide quantum dots bio-conjugates are promising candidates for targeted infrared molecular imaging and future infrared tissue imaging applications. Because of these many characters, in this paper, we tagged cancer cells with quantum dots for better imaging in IR region. We synthesized lead sulphide quantum dots using Hines and Scholes method. Surface modification of quantum dots is carried out using L-cysteine. Surface modification makes semiconductor quantum dots water soluble. The amino groups present in L-cysteine will bind to the cancer cells and the thiol group will bind to the quantum dots. Confocal Raman spectroscopy is used to image the cancer cells tagged with modified lead sulphide quantum dots.

More »»

2016

Jinchu .I, Jyothi .R, Pandurangan Nanjan, K .S.Sreelatha, Dr. Krishnashree Achuthan, and Dr. Sreekala C. O., “Anthraquinones- A probe to enhance the photovoltaic properties of DSSC”, International Journal of Electrical and Computer Engineering (IJECE), vol. 6, no. 3, pp. 1274-1280, 2016.[Abstract]


Natural dye sensitized solar cells are a promising class of photovoltaic cells with the capacity of generating green energy at low production cost since no expensive equipment is required in their fabrication. Photovoltaics are a precious technology in the hasty world where energy prices are goes on increasing within seconds. Researchers are focusing to facilitate for producing eco-friendly, low cost and more efficient dye sensitized solar cells. In the present work we discuss the comparative photovoltaic studies of Lawsone, a natural dye from henna plant and Alizarin, a natural dye from the root of madder for fabricating the Dye sensitized solar cells (DSSCs). The absorption spectrum of Lawsone and Alizarin is found to be shifted to the longer wavelength region after the complex formation. As a result there is a significant increase in short circuit current density and conversion efficiency. This result compares with the standard dye i.e. N719 dye.

More »»

2015

B. Krishnan, .M, A., .S, A., .J, S., Kumar.M, K., .U.S, S., and Dr. Sreekala C. O., “Electrospun TIO2 nanofibers as a matrix to enhance the drug loading”, IJARSE, vol. 4, no. 05, 2015.

2015

Dr. Sreekala C. O., “Photovoltaic studies of dye sensitized solar cell with modified PEDOT:PSS as counter electrode”, International Journal of Advance Research in Science and Engineering, vol. 4, no. 4, pp. 90-95, 2015.

2015

Dr. Sreekala C. O., Jinchu, I., Sajeev, U. S., Achuthan, K., and Sreelatha, K. S., “Photoanode Engineering Using TiO2 Nanofibers for Enhancing the Photovoltaic Parameters of Natural Dye Sensitised Solar Cells”, Journal of Nano-and Electronic Physics, vol. 7, no. 4, pp. 4002-1, 2015.[Abstract]


Dye Sensitized solar cell (DSSC) have been looked upon as having the potential to modernize photovoltaic as a cost effective technology. Especially nanostructured DSSC is proposed to have the capability to boost the efficiency by limiting charge recombination, thereby increasing the charge transportation which affects the overall conversion efficiency favourably. In the present work we discuss the effect of nanofibers as photo anode for increasing the efficiency of a dye sensitized solar cell. As we know nanostructured metal oxides have paying much attention in the field of photovoltaics due to their physical properties and dimensionality. This type of geometry provides direct and spatially separated charge transport channels for electrons and holes. TiO2 single-crystalline nanofibers of different diameter are prepared by electrospinning process and TiO2 nanoparticles by doctor blade technique are used for fabricating the device using natural sensitizers.

More »»

2014

I. Jinchu, Dr. Sreekala C. O., and K.S. Sreelatha, “Dye sensitized solar cell using natural dyes as chromophores-review”, Materials Science Forum, vol. 771, pp. 39-51, 2014.[Abstract]


The molecular dye is an essential component of the Dye sensitized solar cell (DSSC), and improvements in efficiency over the last 15 years have been achieved by tailoring the optoelectronic properties of the dye. The most successful dyes are based on ruthenium bipyridyl compounds, which are characterized by a large absorption coefficient in the visible part of the solar spectrum, good adsorption properties, excellent stability, and efficient electron injection. However, rutheniumbased compounds are relatively expensive, and organic dyes with similar characteristics and even higher absorption coefficients have recently been reported; solar cells with efficiencies of up to 9% have been reported. Organic dyes with a higher absorption coefficient could translate into thinner nano-structured metal oxide films, which would be advantageous for charge transport both in the metal oxide and in the permeating phase, allowing for the use of higher viscosity materials such as ionic liquids, solid electrolytes or hole conductors. Organic dyes used in the DSSC often bear a resemblance to dyes found in plants, fruits, and other natural products, and several dye-sensitized solar cells with natural dyes have been reported. This paper gives an over-view of the recent works in DSSC using the natural dyes as chromophores. © (2014) Trans Tech Publications, Switzerland. More »»

2014

I. Jinchu, Sharma, A. B., Dr. Sreekala C. O., K.S. Sreelatha, and Dr. Krishnashree Achuthan, “Enhanced photovoltaic performance of the dye sensitized solar cell using natural dyes with surface modification of the photoanode”, Materials Science Forum, vol. 771, pp. 159-168, 2014.

2014

V. Kumar. A, Dr. Sreekala C. O., M, M., Ashok, A., and Rasheed, R., “Benchtop Nanoscale Patterning using Soft Lithography for the Printing of DNA Molecules”, International journal of Engineering research and technology, vol. 3, 2014.

2013

Dr. Sreekala C. O., Roy, M. S., Sreelatha K. Sharma, Kumar, K. B. S. P., and Jinchu, I., “Functionalized Multi Walled Carbon Nanotubes (MWCNTs) for enhanced Photocurrent in Dye Sensitized Solar Cells”, Journal Of Nanostructure in Chemistry, vol. 3, 2013.[Abstract]


The influence of the incorporation of nitric acid-treated (functionalized) multi-walled carbon nanotubes (f-MWCNTs) and unmodified MWCNTs in TiO2 films are investigated by observing the photocurrent-voltage characteristics of dye-sensitized solar cells (DSSCs) with and without MWCNTs. The short-circuit photocurrent (J sc) of the modified DSSC increased by 46% compared with that of a cell with plain TiO2 film. The open-circuit voltage remained the same for all cases. The enhanced J sc is explained by the increased surface area of the film, enhanced cluster formation of TiO2 particles around f-MWCNTs, and improved interconnectivity of TiO2 particles in the presence of f-MWCNTs. The efficiency of the cell increased by 45% due to J sc enhancement.

More »»

2012

Dr. Sreekala C. O., Jinchu, I., Sreelatha, K. S., Janu, Y., Prasad, N., Kumar, M., Sadh, A. K., and Roy, M. S., “Influence of Solvents and Surface Treatment on Photovoltaic Response of DSSC Based on Natural Curcumin Dye”, Photovoltaics, IEEE Journal of, vol. 2, pp. 312–319, 2012.[Abstract]


Dye-sensitized solar cells have recently drawn much attention because of their cost effectiveness and easy manufacturing process. However, the challenge lies in minimizing the cost of sensitizer dyes and the platinum-based counter electrode. Natural dyes such as red cabbage, red perilla, rosella, blue pea, and curcumin represent a low-cost, environmentally friendly alternative to costly ruthenium-based complexes for sensitization of nc-TiO$_2$. Attempts are being made to improve the efficiency of a cell based on natural dyes by way of selecting a proper sensitizer, modifying the surface of a working electrode by chemical treatment, and replacing a platinum-based counter electrode. We have adopted two approaches to improve the photovoltaic response of a cell, i.e., 1) modifying the surface of a working electrode by treating it with HCl and TiCl$_4$ and 2) using different organic solvents to enhance the extent of sensitization. PEDOT:PSS grown over graphite-coated fluorine-doped tin oxide is used as a counter electrode to catalyze the reduction of triiodide (${rm I}_3^ -$) to iodide (I$^-$). A TiCl$_4$ -treated photoelectrode, on sensitization with curcumin, gives maximum power conversion efficiency. The impact of the solvent's polarity in dye diffusion was determined with cyclic voltametry. Kelvin probe, SEM, and Raman spectroscopy are employed to justify the surface modification of nc-TiO$_2$ induced by TiCl$_4$ treatment.

More »»

Publication Type: Conference Proceedings

Year of Publication Title

2019

Dr. Sreekala C. O., Dr. Sundararaman Gopalan, and Baby Sreeja S. D., “Piezoelectric energy harvesting system suitable for remotely placed sensors with inter-digitated design”, Publisher Logo Conference Proceedings, vol. 2162, 1 vol. 2019.[Abstract]


Powering of remotely placed sensors or health monitoring devices for bridges, large buildings or aircrafts, are more difficult. Here comes the need of an energy harvesting system that can scavenge energy from the vibrations produced by the wind or vibrations from the surroundings. Piezoelectric Energy Harvesting System (PEHS) is found suitable for these applications, since it is capable of converting the mechanical vibrations or pressure variations into electrical output. Piezoelectric materials are preferred due to the attractive features like high energy density, compactness and light weight. They are most suitable for powering Structural Health Monitoring (SHM) sensors of aircraft structures, bridges, buildings etc. For optimizing the PEHS, understanding and characterization of the sources of vibration/ stress and the displacement are helpful. Introduction of interdigitated electrodes in the PEHS ensure the uniform electric field along the piezoelectric fiber material and hence, enhance the actuation. This is really good news for the electronic designers that, the energy harvested from the Interdigitated PEHS can be used for providing power to many remote applications like structural health monitoring, wireless sensors and other such requirements.

More »»

2019

S. P. Rajan, Philip, T. Elza, Baiju, A., Meenupriya, R., Binoy, K., Krishna, G., Hegde, V., and Dr. Sreekala C. O., “Synthesis and characterization of vanadium pentoxide nanofibrils for lithium ion batteries”, AIP Conference Proceedings 2162. 2019.[Abstract]


The paper demonstrates the synthesis and characterization of vanadium pentoxide (V2O5) nanofibrils. Confirmation of Vanadium pentoxide nanofibrils synthesized by solution process is carried out by FESEM analysis and XRD peaks. Further, thin films with these nanofibrils are deposited on Indium tin oxide (ITO) coated glass plates and its electrochemical properties are analyzed. The studies conducted on these nanofibrils give noteworthy, versatile, and appreciated information to materials chemistry and its thin film is a suitable candidate as a cathode in Lithium-ion batteries.

More »»

2019

Dr. Sreekala C. O., Hegde, V., Nivin, T. S., Sreeja, S. D. Baby, and Dr. Sundararaman Gopalan, “Photovoltaic studies of hybrid metal oxide semiconductors as photo anode in dye sensitized solar cells”, AIP Conference Proceedings. 2019.[Abstract]


Dye sensitized solar cells (DSSCs) have fascinated researchers across the globe since their inception in 1991, due to their easy preparation protocols compared to the conventional silicon solar cells and eco-friendly nature. Most of the time best choice of metal oxide semiconductor is TiO2 because of its high electron injection rate. But on the other hand, wide band gap semiconductor such as ZnO has higher stability and electron mobility. We anticipated that combination of these two should help us to get the better devices. In this study, working electrode modification was done by using hybrid metal oxides as in the fabrication of DSSC to increase the efficiency of the device. ZnO nanoparticles were synthesized by sol-gel process. The morphology, porosity and grain size of the ZnO was studied by SEM analysis. The Particle size was further confirmed by XRD analysis. Bulk and nano TiO2 were blended individually with nano ZnO and their photo voltaic parameters were examined. Used combinations were (i) TiO2-n (ii) TiO2-b (iii) ZnO-n (iv) TiO2-n: TiO2-b in 1:1 ratio (v) ZnO-n: TiO2-n in 1:1 ratio (vi) ZnO-n:TiO2-b in 1:1 ratio respectively along with N719 dye. After assembling the electrodes, the current density-voltage characteristics of each of the combinations were evaluated. It was found that among all the combinations TiO2nano and bulk composition in the proportion 1:1 is showing the optimum efficiency than the other compositions.

More »»

2019

A. Albert, Sreelekshmi, N., Jinchu, I., Dr. Sreedevi K Menon, and Dr. Sreekala C. O., “Electron trapping action of functionalized carbon nanotubes and PEDOT: PSS nanocomposite in inverted perovskite solar cell”, AIP Conference Proceedings 2162. 2019.[Abstract]


Organic –inorganic metal halide perovskite light sensitizer is a fast-growing field in photovoltaic which reached a maximum certified efficiency of 22.1%. Contact layer engineering is widely focused areas in the field of perovskite solar cell to increase power conversion efficiency and stability of the cell. PEDOT: PSS is a reliable organic hole transporting material showing intact performance for inverted perovskite solar cell. A nanocomposite of Functionalised multiwalled carbon nanotubes (f-MWCTs) and PEDOT: PSS are functioned as hole transporter. f-MWCTs are taken in two different volume percentages such as 10% volume of PEDOT: PSS, 20% volume of PEDOT: PSS are added to 250µL of PEDOT: PSS to prepare the composite. Transmittance and surface morphology of PEDOT: PSS-f-MWCTs nanocomposite film is analysed. UV-Visible spectrum of MAPbI3 thin film shows an energy gap in between 1.5-1.6eV. In PL-spectrum of MAPbI3 an intense peak is at 428nm. XRD analysis confirms hexagonal phase of MAPbI3. An inverted perovskite solar cell with architecture FTO glass substrate/ PEDOT: PSS-F-MWCTs nanocomposite/ MAPbI3/ TiO2 compact layer/ FTO glass substrate is fabricated and current voltage characterisations are taken. XRD and SEM analysis of TiO2 film is taken. All the synthesis process and fabrication of the cell is carried out at ambient atmospheric conditions. Addition of 20V% of f-MWCTs increase the fill factor to 31% from 21%. MWCTs increase the number of minority carriers in PEDOT: PSS hole conductor. These minority carriers recombine with the positive vacancy formed in the perovskite light absorber. Hence only a smaller number of holes can transfer through PEDOT: PSS. This leads to lowering the value of Isc and retards the performance of the cell.

More »»

2019

A. Anil, Sreedha Sambhudevan, Dr. Sreekala C. O., and B. Shankar, “Effect of matrix type and doping on polyaniline based natural rubber nanocomposites”, AIP Conference Proceedings. 2019.[Abstract]


Conducting flexible nanocomposites were prepared based on polyaniline (doped/un-doped) and natural/nitrile rubber. These materials have a variety of applications like antistatic and anticorrosion coatings, batteries and sensors, organic electronic materials and electromagnetic wave shielding. Polyaniline (PANI) was prepared from aniline in a very simple and economical method [1]. Polyaniline is then doped using hydro bromic acid and citric acid at different molar ratios [2]. The prepared samples were characterized using Fourier Transfer Infrared spectroscopy (FTIR), Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) to confirm the synthesis and particle size. These conducting nano particles were introduced into natural and nitrile rubber matrix using conventional method of mixing at different proportions [3]. Two different rubber matrices were selected to compare the effect of matrix type on the conductivity of resultant composites. The mechanical studies of prepared nanocomposites confirms the uniform distribution of nano powders in the matrix. As the loading of filler in composite increases, a reduction in mechanical property was observed which may be due to the agglomeration of nanoparticles during composite preparation step. Current-voltage measurements were done in Keithley 2420A source meter in voltage range of 0 to 50 Volt. Electrical conductivity of natural rubber increases 5 times on the addition of 20% of PANI, while the increase was up to 15% when doped PANI was introduced. Nitrile rubber samples show superior conductivity than natural rubber samples which may be attributed to the inherent conducting nature of nitrile rubber.

More »»

2017

V. G. Nandakumar, Suresh, S., Dr. Sreekala C. O., Sudheer, S. K., and Pillai, V. P. Mahadevan, “Hemigraphis Colorata As A Natural Dye For Solar Energy Conversion”, Materials Today: Proceedings, vol. 4. Elsevier, pp. 4358-4365, 2017.[Abstract]


Natural dye extracted from Hemigraphis colorata (Red flame) is used as photosensitizer in dye sensitized solar cells along with TiO2 nano particles and its characteristics are studied. The dye is extracted with minimal chemical procedure and is used without further purification. UV-Visible absorption spectroscopy and micro-Raman spectroscopic studies indicate the presence of anthocyanin and beta-carotene in the extracted dye sample. Photovoltaic property of hemigraphis colorata is studied and an energy conversion efficiency of 0.0065% was obtained. The high concentration of anthocyanin in the extracted dye sample is responsible for the photovoltaic property of hemigraphis colorata.

More »»

2012

Dr. Sreekala C. O., Saneesh, P. F., Sreelatha, K. S., Kishnashree, A., and Roy, M. S., “Organic Bulk Heterojunction Solar Cell Based On Rosebengal: Nctio2 And Parameter Extraction By Simulation”, Advanced Materials Research, vol. 403. Trans Tech Publications, pp. 4304-4310, 2012.[Abstract]


In bulk heterojunction solar cells, the donor and acceptor materials are intimately blended throughout the bulk, so that the excitons generated will reach the interface within their lifetime. In this work, Rosebengal (RB) is used as the donor material and nanocrystalline Titanium dioxide (nc TiO2) as the acceptor material. Devices with device structure ITO/RB:TiO2/Ag are prepared and their optical and electrical properties are compared at different temperatures. Optical absorption spectroscopic analysis shows that the absorption of Rose bengal ranges from 650-800 nm corresponding to a band gap of 1.98 eV. Cyclic voltametric analysis, and photo voltaic properties are analysed. Using simulation, the dark current parameters such as ideality factor (n), mobility (µ) potential barrier (φb) and carrier concentration are extracted and tabulated.

More »»

2008

K. S. Sreelatha, Roy, M. S., and Dr. Sreekala C. O., “Photoelectrical Properties of Bulk Heterojunction Devices Based on Rose Bengal and TiO2 Nanoparticle”, Proceeding of the International Conference on Solar Cells IC-SOLACE 2008. pp. 390-392, 2008.

Publication Type: Thesis

Year of Publication Title

2012

Dr. Sreekala C. O., “Studies On Organic Bulk Heterojunction Devices For Photovoltaic Solar Cell Applications”, 2012.