Ultralow Voltage Bias-Switchable Perovskite Photodetectors Enabled by Interfacial Deep-Trap Engineering

Photodetectors capable of switching between photovoltaic (PV) and photomultiplication (PM) modes are highly desirable for adaptive sensing and optical communication, but integrating high sensitivity with high speed remains a fundamental challenge. Here, we overcome this trade-off by demonstrating a bias-switchable perovskite photodetector (PD) based on a quasi-two-dimensional perovskite via interfacial deep-trap engineering. By tailoring interfacial trap states at the perovskite interface, trap-enabled barrier narrowing and facilitated hole injection are activated at low bias, producing high gain without sacrificing speed. The optimized device operates in self-powered PV mode at 0 V, delivering a detectivity (D*) of 1.12 × 1011 Jones and fast rise/fall times (τr/τf) of 2.10/1.21 μs. Under an ultralow reverse bias of -0.3 V, it achieves a record-high external quantum efficiency exceeding 2100%, a D* of ∼1.7 × 1012 Jones, and μs-level τr/τf in PM mode. Compared with state-of-the-art dual-mode PDs, our approach achieves the lowest bias and μs-level response simultaneously. This bias-switchable perovskite PD integrated with PV and PM dual-mode capability eliminates the need for external amplification circuits and provides rapid detection, highlighting significant potential for applications in portable sensing and dynamic optical environments.