Interface modification for silver telluride quantum dots shortwave-infrared photodetectors beyond 1.5 μm

Solution-processed shortwave-infrared (SWIR) photodetectors utilizing colloidal quantum dots (QDs) represent a transformative advancement in next-generation infrared optoelectronics. Although environmentally benign silver telluride (Ag₂Te) QDs have shown promise for SWIR detection, the performance of such devices, especially beyond 1.5 μm, remains constrained by inadequate energy-level alignment at heterojunctions and insufficient passivation of interfacial defects. This study introduces an inorganic bismuth chloride (BiCl₃) interlayer between the SnO₂ electron transport layer and the Ag₂Te QD active layer. This modification simultaneously facilitates effective defect passivation and optimized band alignment, leading to a significant improvement in photocarrier collection efficiency. The resulting BiCl₃-modified Ag₂Te QD photodiodes achieve a record external quantum efficiency (EQE) of approximately 20% at 1540 nm under zero bias, along with a specific detectivity (D*) of 2.3×10¹¹ Jones at room temperature. This work provides valuable insights into interface engineering for developing high-performance eco-friendly SWIR QD optoelectronic devices.