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.

Lead‐free metal halides have recently received sustained attention because of their nontoxicity, low‐cost, as well as excellent stability and optoelectronic properties. However, most of the reported lead‐free metal halides are synthesized via slow solution‐processing at high temperature in toxic solvents, which may impede their commercial applications. Here, a solvent‐free strategy is proposed to synthesize inorganic rubidium copper halides (Rb2CuX3, X = Cl, Br) at room temperature, which exhibit efficient violet emission dominated by a self‐trapped excitons (STEs) mechanism and attractive stabilities against ultraviolet illumination and heating. Thus, Rb2CuX3 powders are employed as emitters and scintillators applied in wireless light communication and X‐ray imaging technologies. Under orthogonal frequency division multiplexing modulation, emitters demonstrate a broad −3 dB bandwidth of 26.3 MHz and a high received data rate of 205.1 Mbps. Additionally, flexible scintillation films based on as‐prepared powders are fabricated and show outstanding X‐ray scintillation properties, including a high spatial resolution of 18.1 lp mm−1 and a low detection limit of 104 nGyair s−1, as well as promising imaging performance for irregular objects. These results suggest large‐scale production of nontoxic Rb2CuX3 and their potential commercialization in fields of high‐speed light communication and X‐ray radiography.

Chalcogenide-based semiconductors have recently emerged as promising candidates for optoelectronic devices, benefiting from their low-cost, solution processability, excellent stability and tunable optoelectronic properties. However, the understanding of their fundamental optoelectronic properties is far behind the success of device performance and starts to limit their further development. To fill this gap, we conduct a comparative study of chalcogenide absorbers across a wide material space, in order to assess their suitability for different types of applications. We utilize optical-pump terahertz-probe spectroscopy and time-resolved microwave conductivity techniques to fully analyze their charge-carrier dynamics. We show that antimony-based chalcogenide thin films exhibit relatively low charge-carrier mobilities and short lifetimes, compared with bismuth-based chalcogenides. In particular, AgBiS 2 thin films possess the highest mobility, and Sb 2 S 3 thin films have less energetic disorder, which are beneficial for photovoltaic devices. On the contrary, Bi 2 S 3 showed ultralong carrier lifetime and high photoconductive gain, which is beneficial for designing photoconductors.