Microcavity Engineering for Tunable, Narrowband Perovskite Photodetectors with Enhanced Detectivity and Wavelength Selectivity

Perovskite photodetectors are highly attractive for narrowband detection, yet most reported devices depend on optical filters or complex architectures, limiting integration and scalability. Here, we present a microcavity–engineered perovskite photodetector that achieves filter-free, multiwavelength narrowband operation. By modulating both the Ag electrode thickness and the perovskite absorber layer thickness, we successfully tune the cavity resonance for wavelength-selective detection across multiple near-infrared bands. The Ag electrode optimization achieves a high performance microcavity, which significantly improves resonance quality. Furthermore, adjusting the perovskite layer thickness allows for precise control over cavity resonance, enabling narrowband detection at 850, 940, and 1040 nm, with peak EQEs of 20.47, 41.62, and 44.26%, respectively. This study demonstrates the critical role of microcavity engineering in overcoming intrinsic absorption limitations, particularly at the perovskite absorption edge, where conventional devices typically struggle. Notably, resonance-induced enhancements remain effective even in weakly absorbing regions, such as near 1040 nm, leading to unexpectedly high responsivity and detectivity. The findings underscore the potential of this filter-free, tunable, and scalable microcavity approach for advancing optoelectronic applications, offering significant improvements in wavelength-selective photodetection without the need for compositional changes to the perovskite absorber.