Oriented Growth of Al₂O₃:ZnO Nanolaminates for Use as Electron‐Selective Electrodes in Inverted Polymer Solar Cells

Abstract

Abstract Atomic layer deposition is used to synthesize Al 2 O 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 2 O 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 2 O 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 2 O 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.