Cyano‐Functionalized Quinoxaline‐Based Polymer Acceptors for All‐Polymer Solar Cells and Organic Transistors
Hoseon You, Hyunbum Kang, Donguk Kim, Jin Su Park, Jin‐Woo Lee, Seungjin Lee, Felix Sunjoo Kim, Bumjoon J. Kim
Abstract
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 1.0×10 −4 cm 2 V −1 s −1 , due to the well‐ordered structure with tight π‐π 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.