Chem. J. Chinese Universities ›› 2023, Vol. 44 ›› Issue (7): 20230148.doi: 10.7503/cjcu20230148

• Article • Previous Articles     Next Articles

Synthesis of Difluorodithienophenazine Based Conjugated Polymers and Their Organic Photovoltaic Performance

ZHANG Zesheng, DENG Yuxin, KONG Lingchen, LUO Mei, WANG Xinkang, ZHANG Lianjie, CHEN Junwu   

  1. Institute of Polymer Optoelectronic Materials and Devices,State Key Laboratory of Luminescent Materials and Devices,South China University of Technology,Guangzhou 510640,China
  • Received:2023-03-29 Online:2023-07-10 Published:2023-05-23
  • Contact: ZHANG Lianjie, CHEN Junwu
  • Supported by:
    the National Natural Science Foundation of China(22179040);the National Key Research and Development Program of China(2019YFA0705900)

Abstract:

Designing electron-deficient unit based on fused ring is an effective strategy for constructing high-performance conjugated copolymers. In this work, a new electron-deficient monomer(DTPZ) with 9,10-difluorodithienophenazine as the core was synthesized, and two new polymers PB-DTPZ and PFB-DTPZ were prepared. The photophysical properties, electrochemical properties, and organic photovoltaic performance of the two polymers as well as their active layer morphologies were studied and analyzed. Polymers PB-DTPZ and PFB-DTPZ possess optical band gaps of 1.70 and 1.68 eV, respectively, showing red-shifted absorption spectra compared with common wide band gap polymers. The PB-DTPZ and PFB-DTPZ also show low-lying HOMO energy levels of ‒5.51 and ‒5.68 eV, respectively, suggesting the electron-deficient feature of DTPZ. Thanks to the more matched HOMO energy level to Y6 acceptor, the PB-DTPZ∶Y6-based binary polymer solar cell can achieve a power conversion efficiency(PCE) of 12.13%, which is higher than that(10.4%) of the PFB-DTPZ∶Y6-based binary device. Due to the deeper HOMO levels and complementary absorption spectra of PB-DTPZ and PFB-DTPZ, the addition of the two polymers as the third component to the PM6∶Y6 system can further improve the PCE, and the resulting ternary devices can deliver PCEs of 17.08% and 16.99%, respectively.

Key words: Fused ring, Copolymer, Difluorodithienophenazine, Polymer solar cell

CLC Number: 

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