Tellurophene-Based N-type Copolymers for Photovoltaic Applications.

Novel tellurophene-based n-type copolymers are synthesized and characterized with thermal analysis, electrochemistry, optical spectroscopy, and DFT calculations. The copolymers demonstrate reversible interactions with bromine. Through tuning of the building blocks and alkyl chains together with device engineering, the maximum power conversion efficiency of all-polymer solar cells improves from 2.8 to 4.3%, which is supported by photoluminescence, atomic force microscopy, transmission electron microscopy, the space charge limit current method, and exciton dynamic studies. These results suggest that tellurophene-based n-type copolymers are promising electron acceptors for organic solar cells and potential sensor materials for bromine detection.