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Metal halide perovskites have emerged as promising candidates for next-generation optoelectronics. However, the present understanding of their recombination processes and trap states within the devices are still limited, which is also inevitable in the state-of-the-art perovskite solar cells with multiple passivation strategies and various additives involved. Recent works have also demonstrated that metal cations incorporated perovskites could potentially reduce the non-radiative losses and improve the device performance to some extent. However, the underlying “doping” mechanism is not clear. In this work, we systematically investigated the trap-induced ultra-long carrier lifetime of the metal cation incorporated perovskites and found that some specific cations could extend the carrier lifetime up to ∼100 μs, which could be correlated with the formation of shallow trap states. In addition, such shallow trap-mediated charge dynamics could be effectively probed with light-biased time-resolved microwave conductivity technique, which provides additional information to conventional time-resolved photoluminescence.

Chalcogenide‐based semiconductors have recently emerged as promising candidates for optoelectronic applications, mainly benefiting from their facile and low‐cost processability, chemical versatility, and tunable optoelectronic properties. Despite the recent success of chalcogenide‐based thin‐film photovoltaics, they have been barely leveraged in photodetection, mainly due to the complicated charge transport related to the trap states. In addition, most of the chalcogenide photodetectors are reported for broadband, visible photodetection, which is facile but lacks of impact for real applications. However, it is also possible to modulate the charge carrier dynamics of chalcogenide‐based materials, and devise novel devices, which can possess extra compelling features. These possibilities provide strong incentives for a detailed study on the chalcogenides‐based narrowband photodetectors, which are achieved by a filterless, charge collection narrowing strategy. The optimized narrowband photodetectors also exhibit extremely fast‐response (≈240 ns), relatively low dark current and noise, large linear dynamic range, and most importantly tunable spectral discrimination covering the whole range from UV to NIR. These devices also demonstrate great potential for imaging and communication.