Performance improvement of organic solar cells using a hybrid hole transport layer of poly(triarylamine) and molybdenum trioxide

Abstract

In this study, we improved the performance of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′] dithiophene-co-3-fluorothieno [3,4-b]thiophene-2-carboxylate] (Liu et al., 2020; Liu et al., 2020) [6,6]:-phenyl-C 70 -butyric acid methyl ester (PTB7-Th:PC 71 BM)-based organic solar cells (OSCs) by using molybdenum trioxide (MoO 3 ) covered poly(triarylamine) (PTAA) as a hybrid hole transport layer (HTL). Using this technique, an average power conversion efficiency (PCE) of 9.82% was achieved, which was higher than that (8.95%) of OSCs using conventional HTL of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The best performing OSC using PTAA/MoO 3 showed a highest PCE of 10.16%, with a stable power output and negligible hysteresis. Due to the high hydrophobicity of the PTAA/MoO 3 film, the stability of the OSCs was improved simultaneously. After a measurement of 20 days, the PCE degradation was suppressed to 17.5% upon using PTAA/MoO 3 , which was lower than that (28.2%) of PEDOT:PSS-based devices. Additionally, the flexible devices (on polyethylene-naphthalate substrates) showed a high PCE of 8.51%, indicating the good flexibility of PTAA/MoO 3 . • PTAA was protected by MoO 3 and applicable for OSCs. • PCE and stability of the OSCs were improved simultaneously. • PCE of 10.16% was achieved for PTB7-Th:PC 71 BM-based OSCs. • Flexible devices showed a high PCE of 8.51%.