Affiliation:
1. School of Studies in Electronics and Photonics, Pt. Ravishankar Shukla University, Raipur, India
Abstract
In this work, the authors fabricated and characterized efficient inverted organic solar cells by modifying them with a highly transparent sol–gel-derived zinc oxide (ZnO) film as an electron transport layer and optimized molybdenum trioxide (MoO3) as a hole transport layer with a very low-bandgap polymer, poly[N-900-hepta-decanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)] (PCDTBT), in bulk heterojunction (BHJ) composites with the fullerene derivative [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM) BHJ in various solvents. Variations in the sol concentration, thickness, surface and optical characteristics of inverted organic solar cell glass/indium tin oxide/zinc oxide/PCDTBT:PC70BM/molybdenum trioxide/silver (Ag) structures were investigated and analyzed. The thickness of zinc oxide increased as the sol concentration increased from 10 to 100 nm. With the modification of the PCDTBT:PC70BM solvent, the device efficiency improved from 4.22 to 7.43%, which was accompanied by an improvement in the open-circuit voltage (V oc) from 0.87 to 1.03 V and enhancement of the short-circuit current density (J sc) from 9.1 to 13.5 mA/cm2.