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

Observation of high nonlinearity in Bi doped BixIn35-xSe65 thin films with annealing

The present work demonstrates the impact of thermal annealing on the structural, linear, and non-linear optical characteristics of thermally evaporated BixIn35-xSe65 (x = 0, 5, 10, 15 at%) thin films. The prominent crystalline phases have been developed for all annealed films at 450 °C whereas the films remain amorphous at 350 °C annealing. The XRD and Raman analysis showed the phase transformation of Bi-doped films and new Bi2Se3 phases developed upon annealing at 450 °C. The phase transformation induced change increased the linear and nonlinear properties with great extent as seen from the UV-visible optical studies. The direct and indirect optical bandgaps decreased with annealing temperature and also with Bi % content due to the formation of surface dangling bonds near the crystallite sites. The static linear refractive index and high-frequency dielectric constants were increased with annealing. The third-order non-linear susceptibility and non-linear refractive index were found to be greatly influenced by annealing temperature and increased with bismuth content. The FESEM micrographs also showed the phase transformation and EDX analysis showed the composition. The results obtained from the materials showed the potentiality to be useful for photovoltaic and optoelectronic applications.

Synthesis and Characterization of π-SnS Nanoparticles and Corresponding Thin Films

Tin sulfide polymorph (π-SnS) nanoparticles exhibit promising optoelectrical characteristics for photovoltaic and hydrogen production performance, mainly because of the possibility of tuning their properties by adjusting the synthesis conditions. This study demonstrates a chemical approach to synthesize π-SnS nanoparticles and the engineering of their properties by altering the Sn precursor concentration (from 0.04 M to 0.20 M). X-ray diffraction and Raman studies confirmed the presence of pure cubic SnS phase nanoparticles with good crystallinity. SEM images indicated the group of cloudy shaped grains, and XPS results confirmed the presence of Sn and S in the synthesized nanoparticles. Optical studies revealed that the estimated energy bandgap values of the as-synthesized π-SnS nanoparticles varied from 1.52 to 1.68 eV. This work highlights the effects of the Sn precursor concentration on the properties of the π-SnS nanoparticles and describes the bandgap engineering process. Optimized π-SnS nanoparticles were used to deposit nanocrystalline π-SnS thin films using the drop-casting technique, and their physical properties were improved by annealing (300 °C for 2 h).

Effect of Thioacetamide Concentration on the Preparation of Single-Phase SnS and SnS2 Thin Films for Optoelectronic Applications

Eco-friendly tin sulfide (SnS) thin films were deposited by chemical solution process using varying concentrations of a sulfur precursor (thioacetamide, 0.50–0.75 M). Optimized thioacetamide concentrations of 0.6 and 0.7 M were obtained for the preparation of single-phase SnS and SnS2 films for photovoltaic absorbers and buffers, respectively. The as-deposited SnS and SnS2 thin films were uniform and pinhole-free without any major cracks and satisfactorily adhered to the substrate; they appeared in dark-brown and orange colors, respectively. Thin-film studies (compositional, structural, optical, and electrical) revealed that the as-prepared SnS and SnS2 films were polycrystalline in nature; exhibited orthorhombic and hexagonal crystal structures with (111) and (001) peaks as the preferred orientation; had optimal band gaps of 1.28 and 2.92 eV; and exhibited p- and n-type electrical conductivity, respectively. This study presents a step towards the growth of SnS and SnS2 binary compounds for a clean and economical power source.