Author :
Mohammad, Lal ; Farzan Mitul, Abu ; Sigdel, Sudhan ; Dubey, Ashish ; Khatiwada, Devendra ; Adhikari, Nirmal ; Elbohy, Hytham ; Qiquan Qiao
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., South Dakota State Univ., Brookings, SD, USA
Abstract :
In this paper, we demonstrate that low-temperature-processed aluminum-doped zinc oxide (AZO)/ethoxylated polyethylenimine (PEIE) electron transport layer (ETL) significantly improves the performance of poly[(4,4´-bis(2- ethylhexyl) dithieno[3,2-b:2´,3´-d]silole)-2,6-diyl-alt-(2,1,3 benzothiadiazole)-4,7-diyl] (PSBTBT)-based inverted organic solar cells. Different metal oxides, including zinc oxide (ZnO), AZO, ZnO/PEIE, and AZO/PEIE, were used as ETL. The optical and morphological properties of ZnO, AZO, PEIE, and their combination layers were investigated in order to find the favorable ETLs for inverted structure PSBTBT:PC70BM solar cells. Transient photocurrent, photoinduced charge extraction by linearly increasing voltage, and atomic force microscopy were performed to understand the effects of charge transport, recombination, and morphological changes on device performance. Among the various layers, including ZnO, AZO, ZnO/PEIE, and AZO/PEIE, the low-temperature-processed AZO/PEIE combination ETL was the best performing interface layer that achieved the highest device fill factor and energy conversion efficiency.
Keywords :
aluminium; atomic force microscopy; photoemission; solar cells; zinc compounds; ETL; ZnO:Al; atomic force microscopy; charge transport; electron transport layer; energy conversion efficiency; highest device fill factor; inverted organic solar cell performance improvement; inverted structure PSBTBT:PC70BM solar cell interface modification; morphological changes; morphological properties; optical properties; photoinduced charge extraction; recombination; transient photocurrent; II-VI semiconductor materials; Indium tin oxide; Performance evaluation; Photovoltaic cells; Polymers; Zinc oxide; Electron transport layer; interface modification; metal oxide; organic solar cell;