(Received 12 Mar 2014, Accepted 30 Apr 2014; First published online 01 May 2014)
We report a general strategy for fine-tuning the bandgap of donor–acceptor–donor based organic molecules by modulating the electron-donating ability of the donor moiety by changing the benzochalcogenophene donor groups from benzothiophenes to benzoselenophenes to benzotellurophenes. These molecules show red-shifts in absorption and external quantum efficiency maxima from sulfur to selenium to tellurium. In bulk heterojunction solar cell devices, the benzoselenophene derivative shows a power conversion efficiency as high as 5.8% with PC61BM as the electron acceptor.
A review article on stimuli-responsive polymer assemblies with Zhe Sun as a co-author:
Robert B. Grubbs and Zhe Sun, "Shape-changing polymer assemblies," Chem. Soc. Rev.2013, Advance Article DOI: 10.1039/C3CS60079C
A panoply of stimuli-sensitive polymorphic polymer assemblies has been constructed through the intentional synthesis of amphiphilic block copolymers comprising hydrophilic, stimulus-responsive, and hydrophobic blocks. Transformations among canonical micellar forms of polymer assemblies—spherical micelles, wormlike micelles, and vesicles (polymersomes)—have been demonstrated with a number of synthetic systems. This review discusses recent progress in the development and understanding of these systems with a focus on open questions about kinetics of shape change, effects of block copolymer architecture on the rate and nature of the transformation, and potential applications.