Interfacial Potential Modulation for High-Voltage-Stable and Ultra-Sensitive Perovskite Single-Crystal X-ray Detectors

A diagnostic X-ray detector based on a perovskite single crystal (PSC) is demonstrated by introducing a carbon black-doped poly(3-hexylthiophene) (P3HT:CB) interlayer at the anode interface, exhibiting stable operation at high bias voltages and high sensitivity (>1.05 × 10⁶ μC Gy_air^-1 cm^-2). CB doping improves the stability of P3HT against oxidation and modulates interfacial potential, resulting in a hole-blocking barrier that reduces dark current and noise fluctuations under high electric fields. This is associated with improved detector stability, increasing ion migration activation energy from 0.069 to 0.191 eV and reducing effective trap density from 2.04 × 10¹¹ to 2.91 × 10⁹ cm^-3. The detector exhibits a stable baseline at high voltages (up to 200 V) and achieves an ultralow detection limit of 18.44 nGy s^-1. These results suggest the potential of interfacial potential modulation to enhance PSC-based detectors for X-ray detection and radiological imaging.