Photoactive nanocrystals by low-temperature welding of copper sulfide nanoparticles and indium sulfide nanosheets

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 %