An Efficient Ternary Organic Solar Cell with a Porphyrin Based Small Molecule Donor and Two Fullerene Acceptors

Sun, YN (Sun Yanna); Gao, HH (Gao Huanhuan); Zhang, YM (Zhang Yamin); Wang, YC (Wang Yunchuang); Kan, B (Kan Bin); Wan, XJ (Wan Xiangjian); Zhang, HT (Zhang Hongtao); Chen, YS (Chen Yongsheng)^[ 1 ]

CHINESE JOURNAL OF ORGANIC CHEMISTRY, 2018, 38(1): 228-236

DOI: 10.6023/cjoc201706026

  WOS:000424748800026

Abstract

Recently, ternary organic solar cells have emerged as a promising strategy to achieve both high performance and fabrication simplicity for organic solar cells. It has been proved that this strategy is an effective way to achieve improved short-circuit current density (J(sc)) with complementary absorption or to get enhanced open-circuit voltage (V-proportional to) through forming energy level cascade. In this work, we designed and synthesized a thieno[3,2-b] thiphene-substituted porphyrin molecule flanked with two diketopyrrolopyrrole units by ethynylene bridges, named DEP-TT, which exhibited a very low energy bandgap of 1.31 eV and a broad light absorption to 898 nm. The power conversion efficiency (PCE) of binary devices based on DEP-TT and the acceptor [6,6]-phenyl-C-71-butyric-acid-methyl-ester (PC71BM) achieved 7.46% with a relatively low Voc of 0.75 V. Futhermore, the ternary solar cells with 10% indene-C60 bis-adduct (ICBA) achieved high PCE of 8.15%, with higher V-proportional to, J(sc) and a relatively higher PCE based on organic solar cells with a porphyrin-small molecule as the donor. This improved performance is believed to be due to the energy level cascade and synergistic effects of the two acceptors of PCBM and ICBA, which suggestes that the ternary bulk heterojunction (BHJ) strategy is a promising way to improve both V-proportional to and J(sc) simultaneously and thus overall performance for the same donor material.