Towards a long-term stable MAPbBr₃ single crystal-based photoconductor with a high on/off ratio and detectivity

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Lead halide perovskite photodetectors offer high performance but suffer from poor operational stability.
• Surface defects and recombination pathways limit the stability and performance of perovskite-based optoelectronic devices.

Purpose of the Study:

• To enhance the stability and performance of methylammonium lead bromide (MAPbBr₃) single-crystal photodetectors.
• To investigate the effect of ultrathin lead sulfate (PbSO₄) passivation on photodetector characteristics.

Main Methods:

• Fabrication of photodetectors using MAPbBr₃ single crystals.
• Passivation of MAPbBr₃ surfaces with an ultrathin PbSO₄ layer.
• Characterization of device performance, including detectivity and on/off ratios, before and after prolonged operational testing.

Main Results:

• The PbSO₄-passivated photodetector exhibited superior detectivity and on/off ratios compared to the control device.
• Passivation effectively reduced surface trap states and suppressed charge carrier recombination.
• The passivated device retained approximately 56% of its initial detectivity (D*) and an on/off ratio of ~801 after one year, significantly outperforming the control device (~22% D* and ~6 on/off ratio).

Conclusions:

• Ultrathin PbSO₄ passivation is a highly effective strategy for enhancing the stability and performance of MAPbBr₃ single-crystal photodetectors.
• The improved performance is attributed to reduced surface recombination and lower dark current.
• This approach offers a promising pathway for developing robust and reliable perovskite-based optoelectronic devices.