Synthesis and characterization of medium band gap polymers with phosphole[3,2-b:4,5-b′]dithiophene oxide as acceptor unit and their application for polymer photovoltaic devices

•Two conjugated polymers based on dithienophosphole oxide were synthesized.•These polymers showed medium band gaps and very high thermal stability.•The highest PCE of 2.53% is obtained without any device optimization.•This research contributes to design new phosphorus materials for opto-electrical applications.

Two conjugated polymers based on dithienophosphole oxide, PBDT-O-DTPO and PBDT-T-DTPO, were synthesized. Two polymers were fairly soluble in chlorinated solvents, which is enough for device fabrication. According to the UV–vis spectra of films, PBDT-O-DTPO and PBDT-T-DTPO showed absorption onsets of 656 and 675 nm, correspond to optical band gaps of 1.89 and 1.84 eV, respectively. As the results, two polymers exhibited promising photovoltaic properties with power conversion efficiency (PCE) values of 2.23 and 2.53%, respectively, upon blending with PC71BM under AM 1.5 G illumination.

Graphical abstractTwo novel π-conjugated polymers containing dithienophosphole oxide, PBDT-O-DTPO and PBDT-T-DTPO, have synthesized and characterized. Both polymers show medium band gaps, and have very high thermal stability. Without any device optimization, two polymers exhibited promising photovoltaic properties with power conversion efficiency (PCE) values of 2.23 and 2.53%, respectively, upon blending with PC71BM under AM 1.5G illumination, these are records for dithienophosphole oxide-based polymer solar cellsFigure optionsDownload full-size imageDownload as PowerPoint slide