Homologous bromides passivation of CH3NH3PbBr3 single crystals for photodetectors with improved properties

Abstract

Organic hybrid CH3NH3PbBr3 (MAPbBr3) perovskite single crystal (SC) is popular in the field of photoelectric detection due to its outstanding photoelectric properties, but its performance is seriously limited by surface defects. Here, we report a surface passivation method to effectively reduce the surface defects by immersing MAPbBr3 SC in an isopropanol (IPA) solution of CH3NH3Br (MABr). Compared to the untreated SC, the photoluminescence intensity of the homologous MABr treated SC is greatly enhanced by passivation treatment, and the photogenerated carrier lifetime increases from 16 ns to 148 ns. The space charge limited current (SCLC) results show that the trap state density is substantially reduced from 2.34 × 109 cm−3 to 7.22 × 108 cm−3. The X-ray photoelectron spectrum (XPS) of the Pb element presents a significantly reduced peak of metalized Pb, confirming that the metalized Pb ion defects at the surface are effectively passivated. The asymmetry in current-voltage (I-V) curves arising from ion migration is substantially compressed. Furthermore, the photocurrent is significantly enhanced, and the responsivity and detectivity are ∼ 7 times higher in the MABr treated SC device. The results suggest a novel, feasible and efficient strategy to passivate surface defects for perovskite single crystals with improved properties.