On-Substrate Grown MAPbBr3 Single Crystal Diodes for Large-Area and Low-Dark-Current X-Ray Detection

Lead-based organic–inorganic hybrid perovskite single crystals (OIHP SCs) offer promising opportunity for X-ray detection and imaging owing to their high X-ray attenuation coefficient, excellent optoelectronic properties, and simple fabrication processes. Nevertheless, it remains a key challenge to reduce its dark current and meanwhile maintain a high sensitivity. Herein, we developed an on-substrate method for growing methylamine lead bromide (MAPbBr
₃
) SCs on aluminum oxide (Al
₂
O
₃
) layer coated indium tin oxide (ITO) glass. The photodiode based on this approach exhibits an ultralow-dark-current density of 1 nA cm
⁻²
at an operative voltage of −5 V, a signal-to-noise ratio (SNR) more than 80 dB, and meanwhile retaining a high X-ray sensitivity of 2.02
$\times 10^{{3}}\,\, \mu \text{C}\cdot $
${\mathrm {Gy}}_{\text {air}}^{-1} \cdot $
cm
⁻²
. Our further investigation reveals that the dark current was reduced due to two beneficial effects of the Al
₂
O
₃
layer in tandem, including the interfacial defect passivation and blocking of hole injection by increased interfacial energy barrier. Our approach sheds light on advancing the fabrication of high-performance OIHP SCs-based X-ray sensors that can be potentially integrated with large-area readout panel at low temperature.