Extrinsic photoresponse of Ag doped MAPbBr3 perovskite crystals

Photodetectors with a broad spectral range play significant roles in optoelectronic applications. Introducing impurity atoms with the desired energy levels in semiconductors is an effective way to extend the spectral response range of photodetectors. Here, we demonstrate an extrinsic photodetector by introducing Ag+ cations in methylammonium lead bromide (MAPbBr3). The 5 % Ag-doped MAPbBr3 single crystals exhibit excellent response with a high responsivity up to 0.56 A/W, a high detectivity of 2.22 × 1010 jones, and a high response speed of 0.30 s/0.12 s under 700 nm wavelength illumination. Moreover, by the detailed investigation of the crystallinity and energy level distribution, we find that the Pb2+ in MAPbBr3 crystals is partially substituted by the Ag+ impurities, which form the sensitive centers and thus induce the extrinsic response by the photo-carriers transition from the valence band to the sensitive centers. These results extend the spectral response region of perovskite optoelectronic applications and indicate the role of doping impurities with the desired energy level in improving the extrinsic response.