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Keywords:

  • Al2O3:ZnO nanolaminates;
  • atomic layer deposition;
  • inverted organic solar cells;
  • oriented growth

Abstract

Atomic layer deposition is used to synthesize Al2O3: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. Al2O3:ZnO(1:20) nanolaminates are found to exhibit the highest values of electrical conductivity (1.2 × 103 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 Al2O3:ZnO film composition. Polymer-based inverted solar cells using poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) mixtures in the active layer and Al2O3: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.