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Optimization of Solubility, Film Morphology and Photodetector Performance by Molecular Side‐Chain Engineering of Low‐Bandgap Thienothiadiazole‐Based Polymers
Author(s) -
Qi Ji,
Zhou Xiaokang,
Yang Dezhi,
Qiao Wenqiang,
Ma Dongge,
Wang Zhi Yuan
Publication year - 2014
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201401948
Subject(s) - photodetector , materials science , photocurrent , polymer , dark current , side chain , band gap , optoelectronics , active layer , solubility , layer (electronics) , nanotechnology , composite material , organic chemistry , chemistry , thin film transistor
A series of donor–acceptor (D‐A) type low‐bandgap polymers containing the terthiophene and thieno[3,4‐ b ]thiadiazole units in the main chain but different numbers of identical side chains are designed and synthesized in order to study the effect of side chain on the polymer properties and optimize the performance of polymer photodetectors. Variation in the side chain content can influence the polymer solubility, molecular packing, and film morphology, which in turn affects the photodetector performance, particularly with regard to the photoresponsivity and dark current. X‐ray diffraction patterns indicate that molecular ordering increases with more side chains. Atomic force microscopy shows that appropriate morphology of the active layer in the polymer photodetector is necessary for high photocurrent and low dark current. Using BCP as a hole blocking layer (10 nm), the photodetector based on P4 exhibits the optimized performance with specific detectivity of 1.4 × 10 12 Jones at 800 nm, which is among the best reported values for polymer photodetectors and even comparable to that of a silicon photodetector.