Resonant Cavity Effect for Spectrally Tunable and Efficient Narrowband Perovskite Photodetectors

Narrowband photodetectors with precise spectral control offer significant potential for applications such as color imaging and machine vision. However, existing demonstrations have encountered challenges due to restricted absorption, the need for additional filters, or the inclusion of thick absorbing layers to facilitate charge collection filtering mechanisms. These constraints have resulted in suboptimal detectivity, inadequate color control, or slow response. Here, we exploit cavity resonance enhancement to demonstrate a highly spectral selective and robust perovskite photodetector, showing 2.4-fold EQE enhancement at the main narrowband peak with respect to a broadband photodetector counterpart of the same perovskite thickness. This device architecture achieves peak external quantum efficiency of 80%, responsivity of 0.41 A W^-1, and detectivity of 3.7 × 10¹¹ Jones at the main narrowband peak, with a secondary signal below 450 nm that can be mitigated with advanced photonic crystal as proposed. Additionally, the resonant cavity-enhanced photodetector offers a rapid switching of 0.9 μs and low noise of 0.57 pW Hz^-1/2. Our demonstration shows precise tuning of the main narrowband photodetection characteristics across a 100 nm spectral range by simply varying the thickness of the perovskite layer, ensuring device efficiency and stability across the wavelength region around 560 to 660 nm, where most perovskite devices suffer from degradation due to halide segregation. This work demonstrates the practical integration of resonant cavity enhancement in perovskite photodetectors and paves the way for high-performance optical sensing, multispectral imaging, and wavelength-selective photonic devices.