Tunable photoresponse in twisted lead iodide homostructures via exciton-phonon coupling

•A bottom-up-solution-based epitaxial method has been presented to synthesize tPHs •Twist-angle-triggered tunable exciton-phonon coupling in tPHs is clarified •The tPH-based photodetectors achieve tunable broadband photoresponse Twisted-angle-induced unusual electrical and optical properties in van der Waals homostructures have received extraordinary attention recently. However, these emerging properties have rarely been applied to optoelectronic devices. Here, we demonstrate broadband photoresponse capable of overcoming the band-gap limitation of semiconductors in the twisted lead iodide homostructures. The twist angle triggered strong and tunable exciton-phonon coupling leading to the formation of a self-trapped energy level within the band gap, which extends the photoresponse of lead iodide from the ultraviolet to the near-infrared region. The fabricated photodetectors based on twisted lead iodide homostructures exhibit an ultralow dark current (fA level) and a fast response (μs level) as well as a high responsivity from the ultraviolet to near-infrared range (398 mA/[email protected] nm and 0.511 mA/[email protected] nm). Our work presents a simple strategy to realize broadband photodetectors and demonstrates the potential of twisted two-dimensional (2D) structures for next-generation optoelectronic applications. Twisted-angle-induced unusual electrical and optical properties in van der Waals homostructures have received extraordinary attention recently. However, these emerging properties have rarely been applied to optoelectronic devices. Here, we demonstrate broadband photoresponse capable of overcoming the band-gap limitation of semiconductors in the twisted lead iodide homostructures. The twist angle triggered strong and tunable exciton-phonon coupling leading to the formation of a self-trapped energy level within the band gap, which extends the photoresponse of lead iodide from the ultraviolet to the near-infrared region. The fabricated photodetectors based on twisted lead iodide homostructures exhibit an ultralow dark current (fA level) and a fast response (μs level) as well as a high responsivity from the ultraviolet to near-infrared range (398 mA/[email protected] nm and 0.511 mA/[email protected] nm). Our work presents a simple strategy to realize broadband photodetectors and demonstrates the potential of twisted two-dimensional (2D) structures for next-generation optoelectronic applications.