Highly Efficient Surface Passivation with Cation-Exchanged Quasi-2D Perovskites for High-Sensitivity and Low-Dose...

Area of Science:

• Materials Science
• Medical Imaging Technology
• Solid-State Physics

Background:

• Perovskite-based X-ray flat-panel detectors (FPDs) offer potential for next-generation low-dose, high-resolution imaging.
• Polycrystalline thick films in FPDs suffer from interfacial defects, leading to nonradiative recombination, increased dark current, reduced sensitivity, and poor contrast-to-noise ratio (CNR).

Purpose of the Study:

• To develop a universal strategy for passivating interfacial defects in perovskite FPDs.
• To enhance the performance of perovskite FPDs for low-dose and high-resolution X-ray imaging applications.

Main Methods:

• A sequential thermal evaporation and liquid-phase reaction (STELR) method was employed to create a quasi-2D perovskite passivation layer on 3D perovskites.
• This cation-exchange strategy aims to reduce surface trap density and suppress noise in the detectors.

Main Results:

• The STELR passivation reduced surface trap density by nearly an order of magnitude.
• Noise current density was suppressed to 6 × 10^-14A Hz^-1/2.
• The passivated detector demonstrated high sensitivity (59,040 μC Gy_air^-1 cm^-2), a low detection limit (18.6 nGy_air s^-1), and superior spatial resolution (0.71 lp/pixel).

Conclusions:

• The developed passivation strategy effectively mitigates interfacial defects in perovskite FPDs.
• The enhanced detectors maintain high-quality X-ray imaging (CNR = 2.09) even at ultralow doses (29.9 μGy_air).
• This technology holds significant potential for advancing clinical and industrial low-dose imaging systems.