writer：J. Qi, J. Han, X. Zhou, C. Guo, D. Yang, W. Qiao, Y. Li, D. Ma, Z. Y. Wang
keywords：Low-Bandgap Compound
source：期刊
specific source：J. Phys. Chem. C, 2015, 119 (45), pp 25243–25251
Issue time：2015年

Several π-conjugated compounds based on diketopyrrolopyrrole and trithiophene substituted with different end groups (alkyl, alkyloxy, and alkylthio) were designed and synthesized for investigation of the material properties and photodetector performance brought by subtle changes in the end groups. Among all, compound 4 with hexylthio groups exhibits the most red-shifted absorption, strongest molecular stacking, highest mobility, and ideal film morphology. These unique properties make it a promising material for use in small-molecule photodetectors. Photodetector SMPD-4 based on compound 4 exhibits broad response from 300 to 900 nm and a high specific detectivity (D*) of 1.3 × 10¹³ Jones at 650 nm under ?0.1 V. This result is among the best values reported for solution-processed small-molecule photodetectors and even in the same order of conventional silicon photodetector. The molecular structure–material property–device performance relationships are established with these compounds. This work suggests that end-group engineering is a useful method in tuning the material properties and device performance of organic semiconductors.

http://pubs.acs.org/doi/abs/10.1021/acs.jpcc.5b08471