Holistic Design of Charge Transfer Layers for Highly Efficient and Stable AgBiS₂ Quantum Dot Photodetectors

Developing highly efficient and stable photodetectors based on eco-friendly AgBiS₂ quantum dots (QDs) has garnered significant attention. However, optimizing charge transfer layers (CTLs) to enhance device performance and stability remains a critical challenge. Here, the study presents the development of highly efficient, stable, fully inorganic, self-powered AgBiS₂ QD-based photodetectors through the holistic design of CTLs, consisting of zinc-copper-indium-sulfide QDs blended with black phosphorus nanosheets as hole-transport layers, and unzipped carbon nanotubes doped with ZnO nanoparticles as electron-transport layers. The rationally designed CTLs exhibit well-matched energy-level alignment with the AgBiS₂ QDs layer and balanced charge mobility, resulting in a robust and efficient charge transfer system. The optimized device exhibits a responsivity of 20 mA/W and a detectivity of 1.9 × 10¹⁰ Jones at 1000 nm, among the best performance for heavy metal-free QD-based photodetectors. The all-inorganic nature of the devices demonstrates excellent stability for over 2 months in air, with minimal degradation in performance. Furthermore, these enhanced self-powered AgBiS₂ QD-based photodetectors are used as light sensors in the receiver terminal of a near-infrared optical communication system. This work presents a comprehensive approach to the holistic design of CTLs in AgBiS₂ QD-based photodetectors for achieving superior device performance and long-term stability.