High-performance and self-powered photodetectors from an S-scheme Cs₂SnI₂Cl₂/Cs₂TiI₆ heterojunction: a DFT+NAMD study

The recently reported two-dimensional (2D) Ruddlesden-Popper perovskite materials exhibit a plethora of advantages, making them an ideal candidate for constructing high-performance photodetectors. The mixed 2D/3D Cs₂SnI₂Cl₂/Cs₂TiI₆ heterojunction is an S-scheme heterojunction and has excellent light trapping ability. Due to the spontaneous transfer of carriers caused by different work functions, a built-in electric field is formed in the heterojunction and the self-powered capability is provided. Through the nonadiabatic molecular dynamics (NAMD) method, it is found that the heterojunction exhibits fast photoresponse, low losses and efficient carrier separation. In addition, biaxial compressive strain can not only broaden the photoresponse of the Cs₂SnI₂Cl₂/Cs₂TiI₆ heterojunction in the near-infrared region and enhance the optical absorption coefficient of the heterojunction, but also enhance the self-powered ability of the heterojunction. Our discoveries present a highly effective avenue for the future development of high-performance, self-powered hybrid optoelectronic devices.