Effect of electron-withdrawing fluorine and cyano substituents on photovoltaic properties of two-dimensional quinoxaline-based polymers

Seok Woo Lee; M D Waseem Hussain; Sanchari Shome; Su Ryong Ha; Jae Taek Oh; Dong Ryeol Whang; Yunseul Kim; Dong-Yu Kim; Hyosung Choi; Dong Wook Chang

doi:10.1038/s41598-021-03763-1

Effect of electron-withdrawing fluorine and cyano substituents on photovoltaic properties of two-dimensional quinoxaline-based polymers

Sci Rep. 2021 Dec 21;11(1):24381. doi: 10.1038/s41598-021-03763-1.

Authors

Affiliations

¹ Department of Industrial Chemistry, Pukyong National University, 48513, Busan, Republic of Korea.
² Department of Chemistry, Research Institute for Natural Science and Institute of Nano Science and Technology, Hanyang University, 04730, Seoul, Republic of Korea.
³ Department of Advanced Materials, Hannam University, Daejeon, 34054, Republic of Korea.
⁴ School of Materials Science and Engineering (SMSE), Research Institute of Solar and Sustainable Energies (RISE), Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Republic of Korea.
⁵ Department of Chemistry, Research Institute for Natural Science and Institute of Nano Science and Technology, Hanyang University, 04730, Seoul, Republic of Korea. hschoi202@hanyang.ac.kr.
⁶ Department of Industrial Chemistry, Pukyong National University, 48513, Busan, Republic of Korea. dwchang@pknu.ac.kr.

^# Contributed equally.

Abstract

In this study, strong electron-withdrawing fluorine (F) and cyano (CN) substituents are selectively incorporated into the quinoxaline unit of two-dimensional (2D) D-A-type polymers to investigate their effects on the photovoltaic properties of the polymers. To construct the 2D polymeric structure, electron-donating benzodithiophene and methoxy-substituted triphenylamine are directly linked to the horizontal and vertical directions of the quinoxaline acceptor, respectively. After analyzing the structural, optical, and electrochemical properties of the resultant F- and CN-substituted polymers, labeled as PBCl-MTQF and PBCl-MTQCN, respectively, inverted-type polymer solar cells with a non-fullerene Y6 acceptor are fabricated to investigate the photovoltaic performances of the polymers. It is discovered that the maximum power conversion efficiency of PBCl-MTQF is 7.48%, whereas that of PBCl-MTQCN is limited to 3.52%. This significantly reduced PCE of the device based on PBCl-MTQCN is ascribed to the formation of irregular, large aggregates in the active layer, which can readily aggravate the charge recombination and charge transport kinetics of the device. Therefore, the photovoltaic performance of 2D quinoxaline-based D-A-type polymers is significantly affected by the type of electron-withdrawing substituent.