A Universal Nonhalogenated Polymer Donor for High-Performance Organic Photovoltaic Cells.

Non-halogenated polymers have great potential in commercialization of organic photovoltaic (OPV) cells due to their advantage in low-cost preparation. However, non-halogenated polymers usually have high HOMO energy levels and inferior self-aggregation properties in solution, thus resulting in low power conversion efficiencies (PCEs). Herein, two non-halogenated polymers, PB1 and PB2, are prepared. When the polymers were used to fabricate OPV cells with the BTP-eC9, the PB1-based device only gave a PCE of 5.3%, while the PB2-based device showed an outstanding PCE of 17.7%. After the introduction of PBDB-TF as the third component, the PB2:PBDB-TF:BTP-eC9-based device with an optimal weight ratio of 0.5:0.5:1 achieved a PCE up to 18.4%. More importantly, PB2 exhibited good compatibility with various non-fullerene acceptors to achieve better PCEs than those of classical polymer (PBDB-T and PBDB-TF)-based devices. When PB2 was combined with wide bandgap electron acceptor (F-BTA3), this device showed the excellent PCE of 27.1% and 24.6% for 1 and 10 cm2 devices, respectively, under light intensity of 1000 lux light-emitting diode illumination. These results provide new insight in the rational design of novel non-halogenated polymer donors for further developing low-cost materials and broadening the application of OPV cells. This article is protected by copyright. All rights reserved.