Organic photodetectors with UV-sensitivity are of great potential for various optoelectronic applications. Integration of high charge carrier mobility, long exciton diffusion length as well as unique UV-sensitivity for active materials is crucial for construction of UV-sensitive devices with high performance, however, very few organic semiconductors can integrate these properties simultaneously. Herein, two novel organic semiconductors containing large steric hindrance triphenylamine groups, 1,6-distriphenylamineethynylpyrene (1,6-DTEP) and 2,7-distriphenylamineethynylpyrene (2,7-DTEP) are designed and synthesized. It demonstrates that the single crystals of both 1,6-DTEP and 2,7-DTEP exhibit superior integrated optoelectronic properties of high charge carrier mobility, unique UV absorption, high photoluminescence quantum yields as well as small exciton binding energies. Organic phototransistors constructed using 1,6-DTEP and 2,7-DTEP single crystals show ultrasensitive performance with ultra-high photoresponsivity of 2.86 × 106 and 1.04 × 105 A W-1 , detectivity (D*) of above 1.49 × 1018 and 5.28 × 1016 Jones under 370 nm light illumination, respectively. It indicates the great potential of 1,6-DTEP and 2,7-DTEP-based phototransistors for organic UV-photodetector applications and also provides a new design strategy to develop series of better performance UV photoelectric organic materials for related research in organic optoelectronics.
Keywords: UV response; distriphenylamineethynylpyrene derivatives; organic phototransistors; single crystals; ultra-high detectivity.
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