Optimization of SbS Nanocrystal Concentrations in PHT: PCBM Layers to Improve the Performance of Polymer Solar Cells.

In this study, polymer solar cells were synthesized by adding SbS nanocrystals (NCs) to thin blended films with polymer poly(3-hexylthiophene)(PHT) and [6,6]-phenyl-C61-butyric-acid-methyl-ester (PCBM) as the p-type material prepared via the spin-coating method. The purpose of this study is to investigate the dependence of polymer solar cells' performance on the concentration of SbS nanocrystals. The effect of the SbS nanocrystal concentrations (0.01, 0.02, 0.03, and 0.04 mg/mL) in the polymer's active layer was determined using different characterization techniques. X-ray diffraction (XRD) displayed doped ratio dependences of PHT crystallite orientations of PHT crystallites inside a block polymer film. Introducing SbS NCs increased the light harvesting and regulated the energy levels, improving the electronic parameters. Considerable photoluminescence quenching was observed due to additional excited electron pathways through the SbS NCs. A UV-visible absorption spectra measurement showed the relationship between the optoelectronic properties and improved surface morphology, and this enhancement was detected by a red shift in the absorption spectrum. The absorber layer's doping concentration played a definitive role in improving the device's performance. Using a 0.04 mg/mL doping concentration, a solar cell device with a glass /ITO/PEDOT:PSS/PHT-PCBM: SbS:NC/MoO/Ag structure achieved a maximum power conversion efficiency of 2.72%. These SbS NCs obtained by solvothermal fabrication blended with a PHT: PCBM polymer, would pave the way for a more effective design of organic photovoltaic devices.