Vasudeva Minnam Reddy

Formation and characterization of CuInSe2 thin films from binary CuSe and In2Se3 nanocrystal-ink spray

CuInSe2 (CISe) thin films were grown on Mo-coated glass substrates by spray coating technique using nanocrystalline ink. The ink was prepared by dissolving binary CuSe and In2Se3 nanoparticles in iso-butanol. The grown films were subsequently annealed in vacuum and selenium atmosphere, and examined by various characterization techniques. The vacuum-annealed films showed the CuSe binary phase along with the CuInSe2 phase, whereas the selenized films showed a single phase CuInSe2. The elemental analysis of the selenized film exhibited near stoichiometry, and the photoluminescence peak was observed in the region of band-to-band transitions (0.97 eV), which indicated the good structural quality of the selenized films. The developed method opens a new prospect for the finetuning of CISe composition by pre-adjusting the composition of each element in the binary to best fit of CISe in the photovoltaic devices.

Eco-friendly synthesis of SnSe nanoparticles: effect of reducing agents on the reactivity of a Se-precursor and phase formation of SnSe NPs

Tin monoselenide (SnSe) nanoparticles (NPs) have great potential to replace the conventional absorbers used in the fabrication of thin film solar cells. However, studies pertaining to the synthesis and fabrication of SnSe NPs-based solar cells are still lacking. This study presents an eco-friendly synthesis of SnSe NPs by a chemical precipitation method in a short reaction time of 10 min. The effect of different reducing agents (such as NaOH, ethylenediamine, Na2SO3, and NaBH4) on the reactivity of a Se-precursor and phase formation of SnSe NPs was investigated in detail. Our study indicated that the reaction between Sn2+ ions complexed by ascorbic acid and Se2− ions provided by the reduction with NaBH4 resulted in the formation of single phase SnSe NPs. For the first time, a SnSe NPs thin film inorganic solar cell with the device structure of SLG/Mo/SnSe NPs/CdS/i-ZnO/Al:ZnO/Ni/Ag was fabricated and tested, which showed an efficiency of 0.43%.