Vertical Pyro‐Phototronic Effect and Lateral Photothermoelectric Effect in Perovskite Single Crystals‐Based Photodetector for Narrowband and Broadband Dual‐Modal Optical Communications

Abstract Creating dual‐modal metal halide perovskite (MHP)‐based photodetectors (PDs) capable of working in either broadband or narrowband modes would enhance optical communication systems. However, challenges such as complex fabrication, and limited detection range (<900 nm) still exist. Herein, self‐powered, dual‐modal PDs‐based on MHPs are demonstrated, which integrate vertical interfacial pyro‐phototronic effect (IPPE) and lateral photothermoelectric effect (PTEE), via doping these crystals with Ag+ and integrating with wide spectrum absorber. The high‐performance narrowband photodetection results from vertical charge collection narrowing effect (CCN)‐assisted IPPE, enabling light with specific wavelength to penetrate into the interface, with high carrier separation efficiency and temperature rise. In lateral PD, broadband metamaterial absorbers as counter electrodes improved photothermal conversion and expanded light absorption, achieving ultra‐broadband responses from 360 to 2200 nm. By changing the halide type of the MHP single crystals (SCs), the specific response band of narrowband PD can be modulated from purple light to red light, while maintaining the wide spectrum response capability. The dual‐modal photodetection is fully used to achieve double encryption during signal transmission. The work offers a promising approach for designing multi‐modal PDs for wireless communication and data security, applicable in optical imaging, biomedical, and intelligent sensing.