Naphthodithiophene‐Based Nonfullerene Acceptor for High‐Performance Organic Photovoltaics: Effect of Extended Conjugation

Journal Article · Thu Nov 23 00:00:00 EST 2017 · Advanced Materials

DOI:https://doi.org/10.1002/adma.201704713· OSTI ID:1410355

Zhu, Jingshuai ^[1]; Ke, Zhifan ^[2]; Zhang, Qianqian ^[3]; Wang, Jiayu ^[4]; Dai, Shuixing ^[4]; Wu, Yang ^[2]; Xu, Ye ^[5]; Lin, Yuze ^[5]; Ma, Wei ^[2]; You, Wei ^[3]; Zhan, Xiaowei  ^[4]

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1. Department of Materials Science and Engineering College of Engineering Key Laboratory of Polymer Chemistry and Physics of Ministry of Education Peking University Beijing 100871 China, Department of Chemistry Capital Normal University Beijing 100048 China
2. State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
3. Department of Chemistry University of North Carolina at Chapel Hill NC 27599 USA
4. Department of Materials Science and Engineering College of Engineering Key Laboratory of Polymer Chemistry and Physics of Ministry of Education Peking University Beijing 100871 China
5. Department of Chemistry Capital Normal University Beijing 100048 China

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.

• Sponsoring Organization: USDOE
• Grant/Contract Number: DE‐AC02‐05CH11231
• OSTI ID: 1410355
• Journal Information: Advanced Materials, Journal Name: Advanced Materials Vol. 30 Journal Issue: 2; ISSN 0935-9648
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: Germany
• Language: English