Enhanced AgBiS2 Colloidal Quantum Dot Infrared Photodetector by Modifying with 2D MXene Nanoflakes

Colloidal quantum dot (CQD) infrared (IR) photodetectors exhibit great application potential in the fields of optical communication, environmental monitoring, imaging, and wearable sensing. Specifically, AgBiS₂ CQD IR photodetectors have garnered extensive attention because of their excellent photoelectric properties, solution-processability, as well as non-toxicity and environmental friendliness. However, the high trap density and relatively low carrier mobility of AgBiS₂ CQDs have limited their development in high-performance IR photodetectors. Herein, a representative 2D transition carbide, Ti₃C₂T_x, is introduced into the AgBiS₂ CQD films to develop enhanced IR photodetectors based on MXene/AgBiS₂ hybrid films. By finely controlling of the MXene additive concentration, this combination possibly helps reduce trap state density in AgBiS₂ films to suppress carrier nonradiative recombination and simultaneously constructs an efficient conductive pathway in AgBiS₂ films to enhance the extraction of photo-generated carriers. Consequently, compared to the pristine AgBiS₂ CQD devices, the MXene/AgBiS₂ CQD-based infrared photodetector exhibits significant promotion in the responsivity, EQE, and estimated normalized detectivity under a broad band from 500 to 900 nm, demonstrating an alternative method for tailoring the performance of AgBiS₂ CQD optoelectronic devices.