Solution-processed photodetector based on Br incorporated perovskite materials

Mixing of anions (I/Br) in metal halides perovskite for photodetectors attracted much attention due to their inexpensive fabrication and vast optoelectronic properties. The main objective of this compositional anion mixing (I/Br) is to improve the stability of bromide-iodide based perovskite devices. A bilayer lateral MAPbI^3-xBr_x/TiO₂ photodetector is designed to observe the performance and stability of the device by changing the ratio of anion. Responsivity, detectivity, and ON/OFF ratio of the photodetector devices are calculated by changing the anion composition. An appropriate (MAPbI₂Br) bromide-iodide ratio promotes the crystallization of film and increases stability of photodetector device from ambient environment. By changing the anion ratio, band gap of MAPbI_3-xBr_x thin films are changed from 1.59 eV to 2.33 eV. Responsivity calculated for MAPbI₃, MAPbBr₃, MAPbI₂Br, and MAPbIBr₂ devices are 5.22 A/W, 0.23 A/W, 1.86 A/W, and 0.70 A/W, respectively, under light illumination of 0.1 mW cm^-2. Under a bias of 5 V, the value of detectivity for MAPbI₃, MAPbBr₃, MAPbI₂Br, and MAPbIBr₂ devices are 2.88 × 10¹³ J, 1.7 × 10¹² J, 1.4 × 10¹³ J, and 5.95 × 10¹² J, respectively. Changing anion composition also affects the on/off ratio of the devices. MAPbI₃, MAPbBr₃, MAPbI²Br, and MAPbIBr₂ devices show on/off ratio of 5 × 10³, 400, 3.6 × 10³, 1.6 × 10³, respectively.