Highly Sensitive MAPbBr3 Single Crystal Photodetector by Surface Reconstruction

Abstract

MAPbBr3 single crystals (SCs) have attracted significant attention due to their low defect density and excellent optoelectronic properties. However, residual solvents introduced during solution-based SC synthesis increase defects and surface roughness, compromising metal–semiconductor contact quality. Meanwhile, ion migration associated with these defects degrades dark current stability, limiting carrier transport. To address these issues, we develop a surface reconstruction strategy (SRS) to remove the residual and passivate defects in MAPbBr3SC. As a result, the device achieves a faster response time, which is reduced from 212 to $2~\mu $ s. In addition, the dark current drift is lowered by approximately two orders of magnitude to an ultralow value of ${8}.{86}~\times ~{10} ^{-{7}}$ nA $\cdot $ mm/(V $\cdot $ s), along with a noise current of ${2}.{54}~\times ~{10} ^{-{13}}$ A/Hz ${}^{\text {1/2}}$ . Benefiting from reduced dark current drift, the outstanding photodetectors (PDs) successfully achieve stable signal acquisition and accurate heart rate (HR) monitoring in a photoplethysmography (PPG) system.