Cyano-Functionalized Quinoxaline-Based Polymer Acceptors for All-Polymer Solar Cells and Organic Transistors

Abstract

Quinoxaline (Qx) derivatives are promising building units for efficient photovoltaic polymers owing to their strong light absorption and high charge-transport abilities, but they have been used exclusively in the construction of polymer donors. Herein, for the first time, Qx-based polymer acceptors (P(A)s) were developed by introducing electron-withdrawing cyano (CN) groups into the Qx moiety (QxCN). A series of QxCN-based P(A)s, P(QxCN-T2), P(QxCN-TVT), and P(QxCN-T3), were synthesized by copolymerizing the QxCN unit with bithiophene, (E)-1,2-di(thiophene-2-yl)ethene, and terthiophene, respectively. All of the P(A)s exhibited unipolar n-type characteristics with organic field-effect transistor (OFET) mobilities of around 10(-2) cm(2) V-1 s(-1). In space-charge-limited current devices, P(QxCN-T2) and P(QxCN-TVT) exhibited electron mobilities greater than 1.0x10(-4) cm(2) V-1 s(-1), due to the well-ordered structure with tight pi-pi stacking. When the P(A)s were applied in all-polymer solar cells (all-PSCs), the highest performance of 5.32 % was achieved in the P(QxCN-T2)-based device. These results demonstrate the significant potential of Qx-based P(A)s for high-performance all-PSCs and OFETs.