Performance improvement of inverted polymer solar cells using quantum dots and nanorod array

Due to the high absorption at short wavelength and the color conversion effect, CdSe/ZnS core–shell quantum dots were blended into poly (3-hexylthiophene):[6,6]-phenyl-C₆₁-butyric acid methyl ester (P3HT:PCBM) as an active layer of invert polymer solar cells (IPSCs). Compared with the IPSCs using P3HT:PCBM active layer, the short-circuit current density was improved from 10.38 to 11.57 mA/cm² and the power conversion efficiency was improved from 3.37 to 3.73% for the IPSCs using P3HT:PCBM:CdSe/ZnS active layer. Since the carrier mobility of organic materials is very small, the carrier collection ability is limited by the short carrier transport length before they are recombined. Therefore, the power conversion efficiency of the resulting organic solar cells is unavoidably restricted by the low carrier collection ability. In this work, to improve carrier collection ability, indium tin oxide (ITO) nanorod array was embedded. Compared with the short-circuit current density of 11.57 mA/cm² and the power conversion efficiency of 3.73% of the IPSCs using P3HT:PCBM:CdSe/ZnS active layer, the short-circuit current density of 15.60 mA/cm² and the power conversion efficiency of 4.86% were obtained for the IPSCs by embedding 1.0 μm periodic ITO nanorod array in the P3HT:PCBM:CdSe/ZnS active layer.