High responsivity of VIS-NIR photodetector based on Ag 2 S/P3HT heterojunction.

Ag 2 S quantum dot (QD) photodetectors (PDs) have attracted a lot of attention in the field of imaging system and optical communication. However, the current Ag 2 S PDs mainly works in the near-infrared band, and its detection ability in the visible band remains to be strengthened. In this paper, we used poly(3-hexylthiophene) (P3HT) with high carrier mobility and Ag 2 S QDs to construct heterojunction PD. Stronger absorption in blends with polymer P3HT compared to single Ag 2 S QDs. The optical absorption spectra show that the Ag 2 S/P3HT has strong light absorption peak at 394 nm and 598 nm. The results show that P3HT significantly enhances the absorption of Ag 2 S QDs from the visible to near-infrared band. The output characteristics, transfer characteristics and fast switching capability of the device at 405 nm, 532 nm and 808 nm were tested. The device has the responsivity of 6.05 A/W, 83.72 A/W and 37.31 A/W under 405 nm, 532 nm, and 808 nm laser irradiation. This work plays an important role in improving the detection performance of Ag 2 S QDs and broadening its applications in photoelectric devices for weak light and wide spectrum detection.