Synthesis of medium bandgap copolymers based on benzotriazole for non-fullerene organic solar cells

Publication date: Available online 14 June 2019Source: PolymerAuthor(s): Shanshan Ma, Yu Song, Zhenfeng Wang, Baitian He, Xiye Yang, Li Li, Baomin Xu, Jie Zhang, Fei Huang, Yong CaoAbstractThree new copolymer donors based on DCN-alt FTAZ PT-68, PT-810-H, and PT-810-L were synthesized by adjusting the alkyl chains and molecular weight. The copolymers showed deep highest occupied molecular orbital (HOMO) levels of about −5.50 eV due to introducing fluorine atoms and cyano electron-withdrawing groups. Therefore, devices based on the copolymers as donors and ITIC as acceptors had high open-circuit voltages (VOC) exceeding 1.00 V. Due to a dicyanodistyrylbenzene (DCN) unit providing rigid and extended conjugation and reducing the backbone torsion, the blended films had high hole mobility values of about 2.50 × 10−3 cm2 V−1 s−1. Devices with the PT-810: ITIC blended film had the highest power conversion efficiency (PCE) of 7.03%, with an open-circuit voltage of 1.04 V, a short-circuit current density of 12.25 mA/cm2, and a fill factor of 55%. These results provide guidance for the design of high-efficiency photovoltaic materials.Graphical abstractBenzotriazole-based medium bandgap copolymer donors were synthesis, which show deep HOMO levels of about −5.50 eV. A PCE of 7.03% was obtain with the device based on PT-810-H: ITIC, with a high open-circuit voltage (VOC) exceed 1.00 V and high hole mobility value about 2.50 × 10−3 cm2 V−1 sâˆ...

Source: Polymer - June 15, 2019 Category: Chemistry Source Type: research