Ga-doped ZnO as an electron transport layer for PffBT4T-2OD: PC70BM organic solar cells.

Ga-doped ZnO(GZO) is investigated as an electron transport layer in organic solar cells based on a promising donor: acceptor system of poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3‴-di(2-octyldode-cyl)-2,2′; 5′,2″; -5″,2‴-quaterthio-phen-5,5‴-diyl)] (PffBT4T-2OD):phenyl-C71-butyric acid methyl ester (PC 70 BM). With the inverted geometry having a configuration of ITO/GZO (40 nm)/PffBT4T-2OD:PC 70 BM (270 nm)/MoO 3 (20 nm)/Al (100 nm), maximum power conversion efficiency (PCE) of 9.74% has been achieved, while it is limited at 8.72% for devices with undoped ZnO. Our study based on the structural, morphological, compositional, and electrical characterizations indicate that suggests enhanced device performance of the GZO-based devices resulted mainly from the improved electrical properties of Ga-ZnO thin films as compared to undoped ZnO. [ABSTRACT FROM AUTHOR]