Inverted polymer solar cells with brush-painted ZnO electron transport layer

Air-stable inverted polymer solar cells (IPSCs) were demonstrated by incorporating ZnO electron transport layer (ETL) fabricated with low-cost and simple brush-painting. IPSC with brush-painted ZnO using commonly used 0.75 M zinc acetate solution in 95% 2-methoxyethanol and 5% ethanolamine showed poor efficiency and reproducibility. By optimizing precursor solution and substrate temperature, thieno[3,4-b]thiopheneibenzodithiophene (PTB7): [6,6]-phenyl C-71-butyric acid methyl ester (PC71BM) based IPSC with high power conversion efficiency (PCE) of 7.63% and desirable device stability was achieved. This indicates that because optimized process conditions are not necessarily transferrable between different techniques, it is worthy of investigation and discussion. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.