We successfully utilize the concept of coalescence and room-temperature sintering to prepare morphologically different nanoparticles. n-Type chalcogenide (CuIn5S8) nanocrystals are synthesized at room temperature by simple mixing of oppositely charged precursor nanoparticles. The coalescence of polycation-coated CuS nanoparticles and negatively charged In2S3 nanoplates is driven by close contact of the particles due to electrostatic interactions. Analysis by X-ray diffraction, transmission electron microscopy (TEM) imaging, and Raman spectroscopy confirms the formation of single-phase CuIn5S8 without traceable secondary phase. In a photovoltaic device, the use of the coalesced particles yields a power conversion efficiency of 1.8 %.
H. Min Lim, Tan, J. Yi, Batabyal Sudip Kumar, Magdassi, S., Mhaisalkar, S. G., and Wong, L. H., “Photoactive Nanocrystals by Low-Temperature Welding of Copper Sulfide Nanoparticles and Indium Sulfide Nanosheets”, ChemSusChem, vol. 7, pp. 3290–3294, 2014.