Oriented Growth of Al_2O_3:ZnO Nanolaminates for Use as Electron-Selective Electrodes in Inverted Polymer Solar Cells

摘要

Atomic layer deposition is used to synthesize Al_2O_3:ZnO(1:x) nanolaminates with the number of deposition cycles, x, ranging from 5 to 30 for evaluation as optically transparent, electron-selective electrodes in polymer-based inverted solar cells. Al_2O_3:ZnO(1:20) nanolaminates are found to exhibit the highest values of electrical conductivity (1.2 ×10~3 S cm~(-1); more than six times higher than for neat ZnO films), while retaining a high optical transmittance (≥80% in the visible region) and a low work function (4.0 eV).Such attractive performance is attributed to the structure (ZnO crystal size and crystal alignment) and doping level of this intermediate Al_2O_3:ZnO film composition. Polymer-based inverted solar cells using poly(3-hexylthiophene) (P3HT):phenyl-C_(61)-butyric acid methyl ester (PCBM) mixtures in the active layer and Al_2O_3:ZnO(1_20) nanolaminates as transparent electron-selective electrodes exhibit a power conversion efficiency of 3% under simulated AM 1.5 G, 100 mW cm~(-2) illumination.