Simple methoxy-substituted quinoxaline-based D-A type polymers for nonfullerene polymer solar cells

Abstract

Two quinoxaline-based D-A-type conjugated polymer donors were designed and synthesized in this study with the aim of developing high-performance nonfullerene polymer solar cells (PSCs). The combination of the electron-donating indacenodithiophene (IDT) and indacenodithieno[3,2-b]thiophene (IDTT) units with the electron-accepting methoxy-substituted 2,3-diphenylquinoxaline moiety (QxM) under the Stille coupling condition produces the target polymers, denoted as PIDT-QxM and PIDTT-QxM, respectively. In these specific molecular architectures, the beneficial two-dimensional arrangement of the electron-donating components in both the horizontal and vertical directions of the central quinoxaline unit is readily achieved. The photovoltaic properties of the polymers were examined by fabricating nonfullerene PSCs with the structure of ITO/ZnO/Polymer:Y6BO/MoO3/Ag. The replacement of the electron-donating IDT in PIDT-QxM with IDTT in PIDTT-QxM could increase the power conversion efficiency (PCE) of the corresponding device from 9.49% to 10.40%. The prominent enhancement in the PCE of the device based on PIDTT-QxM can be primarily ascribed to the significant increase in its short-circuit current density. Moreover, the simple synthetic methods used in this study for manufacturing p-type polymers can provide the additional advantages of cost-effectiveness and scalability.