Methylammonium lead bromide (MAPbBr₃) have emerged as the next-generation materials for self-powered photodetectors due to its easy fabrication protocol and better stability. However, there is still a lack of sufficient understanding of the effect of electrode distance, metal contacts, irradiation power and applied temperature on the performance of MAPbBr₃ SC-based perovskite PDs. Here, we demonstrated the impact of different electrode materials, variable electrode distance,¹ light intensities and temperatures on the performance of MAPbBr₃ SC-based perovskite PDs and analyse them with the help of transient photoresponse and impedance spectroscopy.² This study reveals that the key performance parameters of PD decrease with increasing irradiation intensity as well as increase in Schottky barrier height (SBH) between the metal and the semiconductor, due to changes in charge recombination and carrier lifetime.^2,3 On the other hand, the temperature-dependent study revealed that the performance of PD was found to be related to the increasing scattering of impurities, temperature activated ion accumulation, and phonons, change in conductivity and band gap rather than the change in charge recombination. Next, we fabricated a planar-type PD based on metal doped p-type MAPbBr₃/n-type MAPbBr₃ SC junction photodiode using asymmetric electrode and use the combined effect of electric field due to asymmetric Schottky barrier formation and additional built-in electric field in the p-n junction depletion region demonstrate for the first time to achieve excellent self-powered photodetection properties.⁴ The p-n junction on the MAPbBr₃ single crystal was formed by a controlled epitaxial grow of Ag⁺ doped MAPbBr₃ SC (p-type) on the facet of Sb³⁺ doped MAPbBr₃ SC (n-type). The as-integrated p-n junction device with asymmetric electrodes shows a typical photovoltaic behaviour with a high open circuit voltage of 0.95 V and great sensitivity to 530 nm illumination at zero bias with a responsivity of up to 0.41 A W^-1 and a specific detectivity of 6.39 × 10¹¹ Jones, which are among the highest values reported for MAPbBr₃ single crystal based self-powered photodetectors. In addition, the p-n junction device maintained 80% of the initial performance after being exposed under continuous operation illumination for 12 h in atmospheric condition and restored 94% performance of its initial value after 36 h of storage in the dark. This work provides a new way for designing a high performance self-powered perovskite-based p-n junction photodiodes.