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Results of the scanning electron microscopy (SEM), X-ray diffraction (XRD), optical absorption, photoconductivity (PC), and photoluminescence (PL) studies for the CdSSe:CdCl2,Ho films are presented in this paper. The SEM studies of different CdSSe films show a layered growth structure. A crystalline nature of the films is observed in the XRD studies. The regions with stacking fault were also observed in the X-ray diffractograms. The optical absorption spectra of these films show variations corresponding to the band gaps and the grain-sizes obtained under various deposition conditions and also with annealing. The effect of flux, impurities and annealing on the saturated photo to dark current ratio Ipc/Idc is observed in the PC rise and decay studies. The maximum value of Ipc/Idc ∼107 is obtained for the impurity doped annealed films. The PL emission spectra of CdSSe films show two emission peaks associated with the annihilation of free excitons and the transitions between shallow donor and deep acceptor states. In CdSSe:CdCl2,Ho films, two PL emission peaks are observed at 495 nm and 545 nm corresponding to the transitions 5S2→5I8 and 5F3→5I8, respectively, in Ho. The effect of pH on PL and grain size is also included in the present studies.

In the present work, we report green synthesis of tartaric acid (TA) and triethanolamine (TEA) capped cadmium selenide quantum dots (CdSe QDs) employing chemical bath deposition (CBD) method. The mechanism of capping using non-toxic binary capping agents is also discussed. Stable QDs of various sizes were obtained by varying pH of the bath. The structural, morphological and spectroscopic characterization of the as-prepared samples by XRD, SEM, optical absorption and photoluminescence (PL) is also reported.

ZnO nanoparticles (ZNPs) were synthesized by wet chemical method using poly vinyl alcohol (PVA) templates. Uniform growth, high yield and excellent optical properties were observed in ZNPs synthesized under pulsed microwave irradiation (PMW). Moreover the dangling bonds of ZNPs prepared under PMW were passivated more effectively than in samples prepared without it. Strong UV emission peaks at ~ 360 nm and 380 nm, along with a feeble defect-related visible emission peak at ~ 465 nm, were observed in the room temperature (RT) photoluminescence (PL) spectra of ZNPs. Observation of two distinct excitonic peaks in RT UV-vis optical absorbance spectra and high UV-to-visible PL intensity ratio show high quality of ZNPs prepared by the present method. FTIR spectra were employed to explain the surface passivation mechanism of PVA.

The perovskite-based photovoltaic cells are the best way to convert photon radiation into electrical energy. The fundamental focus of this work is to stimulate and boost the power conversion efficiency (PCE) of an alloy-based CsPb0.75Sn0.25IBr2 perovskite solar cell. The simulation was run on SCAPS-1D cell simulator software (ver. 3.3.09). In this current work, a perovskite CsPb0.75Sn0.25IBr2 with the suitable composition of ions coupled with Tin-based electron transport layers (ETLs)-SnO2 and Mg:SnO2. The thickness and defect density of absorber layer-CsPb0.75Sn0.25IBr2 has been optimized. The impact of the thickness variation of ETL-SnO2 and Mg:SnO2 on device performances was also studied. The effect of working temperature, rate of charge carrier generation, and recombination on photovoltaic outputs like open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), and PCE has been studied and analyzed. The simulated cell achieved an efficiency of 13.82% under optimum conditions. The optimized efficiency was comparatively higher than the experimental efficiency of 11.85%. This study demonstrates the role of optimization of various properties of different layers of solar cells.