Naphthodithiophene‐Based Nonfullerene Acceptor for High‐Performance Organic Photovoltaics: Effect of Extended Conjugation. Issue 2 (23rd November 2017)

• Record Type: Journal Article
• Authors: Zhu, Jingshuai; Ke, Zhifan; Zhang, Qianqian; Wang, Jiayu; Dai, Shuixing; Wu, Yang; Xu, Ye; Lin, Yuze; Ma, Wei; You, Wei; Zhan, Xiaowei
• Is Part Of: Advanced materials. Volume 30:Issue 2(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-11-23
• Subjects: fused‐ring electron acceptors -- naphthodithiophene -- nonfullerene acceptors -- organic solar cells; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201704713
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Naphtho[1, 2‐ b :5, 6‐ b′ ]dithiophene is extended to a fused octacyclic building block, which is end capped by strong electron‐withdrawing 2‐(5, 6‐difluoro‐3‐oxo‐2, 3‐dihydro‐1H‐inden‐1‐ylidene)malononitrile to yield a fused‐ring electron acceptor (IOIC2) for organic solar cells (OSCs). Relative to naphthalene‐based IHIC2, naphthodithiophene‐based IOIC2 with a larger π‐conjugation and a stronger electron‐donating core shows a higher lowest unoccupied molecular orbital energy level (IOIC2: −3.78 eV vs IHIC2: −3.86 eV), broader absorption with a smaller optical bandgap (IOIC2: 1.55 eV vs IHIC2: 1.66 eV), and a higher electron mobility (IOIC2: 1.0 × 10 −3 cm 2 V −1 s −1 vs IHIC2: 5.0 × 10 −4 cm 2 V −1 s −1 ). Thus, IOIC2‐based OSCs show higher values in open‐circuit voltage, short‐circuit current density, fill factor, and thereby much higher power conversion efficiency (PCE) values than those of the IHIC2‐based counterpart. In particular, as‐cast OSCs based on FTAZ: IOIC2 yield PCEs of up to 11.2%, higher than that of the control devices based on FTAZ: IHIC2 (7.45%). Furthermore, by using 0.2% 1, 8‐diiodooctane as the processing additive, a PCE of 12.3% is achieved from the FTAZ:IOIC2‐ based devices, higher than that of the FTAZ:IHIC2‐ based devices (7.31%). These results indicate that incorporating extended conjugation into the electron‐donating fused‐ring units in nonfullerene acceptors is a promising strategy for designing high‐performance electron acceptors. Abstract : A novel fused‐ring electron acceptor (IOIC2) based on naphthodithiophene is designed and synthesized, and compared with a naphthalene‐based counterpart (IHIC2). The IOIC2‐based single‐junction binary‐blend organic solar cells exhibit efficiencies up to 12.3%, much higher than that of IHIC2 (7.45%).