AgBiS₂ colloidal quantum dots (CQDs) possess excellent optoelectronic properties, including high absorption coefficient, environmental friendliness, and facile solution processability. They are regarded as promising candidates to replace toxic Pb and Hg-based CQDs in the field of optoelectronics. However, the energy-levels mismatch between electron transport layer (ETL) and photoactive layer in AgBiS₂ CQDs photodetector affecting the performance of the device. To address this challenge, this study introduces ZnO/MXene bilayer ETL to optimize the interface energy-level alignment. A broad-spectrum, high-performance AgBiS₂ CQDs photodetector has been realized, exhibiting an ultra-low dark current density of 6.1 × 10⁻⁸ A·cm⁻², a broad detection spectrum ranges from 375 to 1120 nm, a specific detectivity (D*) of 7.8 × 10¹⁰ Jones at 980 nm, and a large linear dynamic range (LDR) of 80 dB. The device of bilayer ETL enhances the D* by 3.5 to 7 times compared to the control device by improving charge extraction and suppressing carrier recombination. Furthermore, integrating the photodetector with a thin-film transistor (TFT) array enables high-quality imaging under 850 nm near-infrared (NIR) illumination, demonstrating its significant potential for advanced image sensor applications.

Heavy-metal-free silver based I-III-VI semiconductor nanocrystals (NCs), including ternary silver indium sulfide (AgInS₂) and derivative quaternary silver indium zinc sulfide (i.e., AgInZn₂S₄) NCs, possess advantages of low toxicity, and size-tunable band gaps approaching near-infrared spectral range, which make them candidates for use in optoelectronic and biological devices. Herein, we report syntheses of AgInS₂ based NCs starting from In₂S₃ template, which have been performed both in organic and aqueous phase through cation exchange. As a result, ternary silver indium sulfide and quaternary silver indium zinc sulfide NCs are obtained in both organic and aqueous media, and confirmed to be orthorhombic AgInS₂ NCs and hexagonal AgInZn₂S₄ NCs, respectively. Furthermore, the aqueous AgInZn₂S₄ NCs with red emission and low cytotoxicity are explored for the cancer cell imaging.