Modulating Eco‐friendly Colloidal AgGaS₂ Quantum Dots for Highly Efficient Photodetection and Image Sensing via Direct Growth of Ternary AgInS₂ Shell

Abstract Tailoring the optoelectronic characteristics of colloidal quantum dots (QDs) by constructing a core/shell structure offers the potential to achieve high‐performing solution‐processed photoelectric conversion and information processing applications. In this work, the direct growth of wurtzite ternary AgInS₂ (AIS) shell on eco‐friendly AgGaS₂ (AGS) core QDs is realized, giving rise to broadened visible light absorption, prolonged exciton lifetime and enhanced photoluminescence quantum yield (PLQY). Ultrafast transient absorption spectroscopy demonstrats that the photoinduced carrier separation and transfer kinetics of AGS QDs are significantly optimized following the AIS shell coating. As‐synthesized environmentally benign AGS/AIS core/shell QDs are employed to fabricate photodetectors (PDs), showing a remarkable responsivity of 38.4 A W⁻¹ and a detectivity of 2.4 × 10¹² Jones under visible light illumination (405 nm). Moreover, the fabricated QDs‐PDs exhibit superior image‐sensing capability to record complex patterns with high resolution (160 × 160 pixels) under visible light illumination at 405 and 532 nm. The findings indicate that the direct growth of multinary narrow‐band shell materials on eco‐friendly QDs holds great promise to implement future “green”, cost‐effective and high‐performance optoelectronic sensing/imaging systems.