Synthesis of medium bandgap copolymers based on benzotriazole for non-fullerene organic solar cells. (28th September 2019)

• Record Type: Journal Article
• Authors: Ma, Shanshan; Song, Yu; Wang, Zhenfeng; He, Baitian; Yang, Xiye; Li, Li; Xu, Baomin; Zhang, Jie; Huang, Fei; Cao, Yong
• Is Part Of: Polymer. Volume 179(2019)
• Publication Date: 2019-09-28
• Subjects: Benzotriazole -- Donor materials -- Polymer solar cells; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2019.121580
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Three 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 ( V OC ) 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 cm 2 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/cm 2, and a fill factor of 55%. These results provide guidance for the design of high-efficiency photovoltaic materials. Graphical abstract: Benzotriazole-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 ( V OC ) exceed 1.00 V and high hole mobility value about 2.50 × 10 −3 cm 2 V −1 s −1 .Image 1 Highlights: The devices have high V oc exceeding 1.00 V. The effects of the side alkyl chains and molecular weight on the properties of the copolymers are studied. The deep HOMO levels achieve due to introducing fluorine atoms and cyano electron-withdrawing groups.