Enhanced Performance of AgBiS2 Colloidal Quantum Dot Near-Infrared Photodetectors

Colloidal quantum dot (CQD) near-infrared photodetectors have attracted a lot of interest in the fields of optical communications, environmental surveillance, imaging technologies, and wearable sensors, due to their tunable bandgaps and flexible solution processibility. In particular, AgBiS2 CQDs have been considered a promising candidate nanomaterial for near-infrared photon detection because of their non-toxicity and environmental friendliness. However, the performance improvement of AgBiS2 CQD-based photodetectors is still limited by the high trap states density and relatively low carrier transport properties of CQD film. Herein, we demonstrate a simple and effective strategy to enhance the photoresponse performances of AgBiS2 CQD-based devices by constructing SnO2/AgBiS2 bulk nano heterostructures (BNH). By finely controlling the addition of SnO2 nanocrystals, the non-radiative recombination in AgBiS2 CQDs film was suppressed while the carrier transport in the composite film was simultaneously improved. As a result, the optimized device with 7 wt% SnO2 (ASN7) exhibited a responsivity of 0.161 mA/W and an estimated detectivity of 5.85 × 108 Jones, which are approximately 11.5-fold and 3.5-fold higher than those of the control device, respectively. Additionally, the response speed was significantly accelerated. This work offers an effective approach for enhancing the photoelectrical properties of lead-free AgBiS2 CQD-based near-infrared optoelectronics.