CdSe/CdS Core/Shell nanostructures were prepared by a new green chemical route using starch as capping agent. The structural and optical characterizations of quasi type-II CdSe/CdS Core/Shell film were done by HRTEM, AFM, UV-Vis and PL techniques. The Characteristics I-V curves of this junction confirmed the formation of Schottky contact between silver (Ag) and CdSe/CdS Core/Shell nanostructures. Intrinsic and contact behavior such as saturation current, barrier height, effective Richardson constant, electron affinity and ideality factor were calculated from the current-voltage characterization. The reverse saturation current was remarkably increased to 7.6 × 10 −4 Amp in the fabricated Schottky junction. The barrier height and ideality factor were estimated 0.925 eV and 1.52 respectively. An energy band gap diagram has been proposed as a transportation mechanism of tunneling electrons in between core/shell nanostructures and silver metal interfaces.

The main objective of this work is to investigate the CIGS solar cell performance by replacing the toxic CdS buffer layer from the conventional solar cell structure Ag/ITO/ZnO/CdS/CIGS/W by the non-toxic ZnSe layer using SCAPS-1D software. J-V characteristics of the simulated cell structure show that the efficiency of the solar cell increases from 23.23 % to 23.58 % (with Voc of 0.8202 V, Jsc of 34.86 mA/cm 2 and FF of 82.49 %) due to the use of ZnSe layer. The increase in the efficiency of the cell is attributed to the decrease in photon absorption in the buffer layer due to higher band gap of ZnSe. An additional thin layer was inserted between CIGS and the back contact (W) to eliminate the back surface recombination. This new layer provided an additional hole tunneling action which led to an increase in the solar cell efficiency up to 24.64 %. Moreover, an attempt has been made to investigate the dependence of the CIGS solar cell efficiency on the operating temperature.