Photodetectors generally operate exclusively in either the broadband or narrowband. Developing bifunctional photodetectors that can detect photons in both broadband and narrowband would bring significant versatility to the optoelectronic platform. Nevertheless, the design of bifunctional integrated devices remains challenging due to the differentiated strategies with respect to device structure and material combination. Herein, we propose introducing polyvinylpyrrolidone to increase the viscosity of the perovskite precursor solution, which introduces abundant defects and cavities into the perovskite film while maintaining a relatively low film thickness. Then, we use methylamine gas to postprocess the middle area of the film to promote directional recrystallization and densification, thereby realizing narrowband and broadband dual‐function photodetection in a single device at zero bias. Both ends of the film exhibit a near‐infrared peak response at 780 nm with a narrow full‐width at half maximum of approximately 30 nm without an external bias. The middle broadband photodetector exhibits a high responsivity of 329 mA W−1 and EQE up to 52.46% at 780 nm. We make full use of narrow‐band wavelength selective detection and broadband full‐spectrum detection to achieve double encryption during signal transmission. This work represents an important step toward the realization of perovskite‐based multifunctional integrated devices.

Formamidinium–lead triiodide (FAPbI3) perovskite is considered as one of the most promising perovskite materials for high‐performance photodetectors because of its narrow bandgap and superior thermal stability. Nevertheless, to realize efficient carrier transport and highly performing photodetectors, it imposes the requirement of fabricating α‐FAPbI3 with pure phase, preferred crystal orientation, large grain size, and passivated interface, which still remains challenging. Here, a facile strategy based on additive engineering to obtain pure‐phase FAPbI3 perovskite films by introducing N‐(2‐aminoethyl) acetamide into perovskite precursors is reported. The formation of chemical bond and hydrogen bond between N‐(2‐aminoethyl) acetamide and perovskite reduces the potential barrier in the phase‐transition process from an intermediate yellow phase to a final black phase, passivates the defects of the film, and leads to a high‐quality and phase‐pure α‐FAPbI3 perovskite. A self‐powered photodetector based on the as‐fabricated FAPbI3 film exhibits a maximum responsivity of 0.48 A W−1 at 700 nm with a peak external quantum efficiency of 95% at 440 nm. Moreover, the optimized device remains 83% of the initial performance after 576 h storage at ambient condition. This work provides a simple and feasible scheme for the preparation of high‐quality phase‐pure α‐FAPbI3 perovskite and associated devices.

Metal halide perovskite materials have excellent photoelectric properties, including high absorption coefficient, long charge carrier diffusion length, and low exciton binding energy, making them excellent candidates for photoconversion devices. In the past decade, great progress has been made in improving the performance of perovskite-based solar cells and photodetectors. However, perovskite devices need to be endowed with more functionality to meet practical application requirements. In this regard, the three major trends in perovskite device development involving flexibility, transparency, and self-healing have attracted wide interests. This review first summarizes the fundamental design principles of endowing perovskite devices with more functionality. Specifically, the functionalization is realized through elaborate substrate and electrode selection, perovskite layer modification, and device layout. This review presents the recent advances and specific requirements for functionalization of perovskite devices according to the three basic components: substrate, electrode, and perovskite layer. Finally, potential challenges and future research directions in this field are outlined. The aim of this review is not only to shed light on the basic design principles of functionalized perovskite devices, but also to serve as the roadmap for future exploration in perovskite devices.