title: Improved performances of PCDTBT:PC71BM BHJ solar cells through incorporating small molecule donor.
abstract: We demonstrate bulk heterojunction (BHJ) organic photovoltaics (OPVs) with a power conversion efficiency (PCE) of 6.39% by incorporating a small molecular compound 2-[4-(N-butyl-N-phenylamino)-2,6-dihydroxyphenyl]-4-[(4-(N-butyl-N-phenylamino)-2,6-dihydroxyphenyl)-2,5-dien-1-ylidene]-3-oxocyclobut-1-en-1-olate (SQ-BP) as the additional donor material into a poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT):[6,6]-phenyl C71 butyric acid methyl ester (PC71BM) host binary blend. Incorporating SQ-BP into the PCDTBT:PC71BM host blend film increases the photon harvesting of a ternary photovoltaic device with a broad absorption spectrum from 300 nm to 750 nm, which results in an increased short-circuit current density (Jsc). In addition to efficient photon harvesting, Förster resonance energy transfer (FRET) between PCDTBT and SQ-BP is also the reason for the increase in Jsc. As a result, the PCE of ternary devices with 10 wt% SQ-BP is about 30% greater than that of PCDTBT:PC71BM-based binary OPVs.
authors.affiliation: Key Laboratory of Luminescence and Optical Information (Ministry of Education), Institute of Optoelectronics Technology, Beijing Jiaotong University, Beijing 100044, P. R. China. slzhao@bjtu.edu.cn.
authors.forename: Youqin
authors.initials: Y
authors.lastname: Zhu
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Suling
authors.initials: S
authors.lastname: Zhao
authors.forename: Yan
authors.initials: Y
authors.lastname: Huang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Xu
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Yang
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Xurong
authors.initials: X
authors.lastname: Xu