Heavy-to-light electron transition enabling real-time spectra detection of charged particles by a biocompatible semiconductor

The current challenge of wearable/implantable personal dosimeters for medical diagnosis and radiotherapy applications is lack of suitable detector materials possessing both excellent detection performance and biocompatibility. Here, we report a solution-grown biocompatible organic single crystalline semiconductor (OSCS), 4-Hydroxyphenylacetic acid (4HPA), achieving real-time spectral detection of charged particles with single-particle sensitivity. Along in-plane direction, two-dimensional anisotropic 4HPA exhibits a large electron drift velocity of 5 × 10^5 cm s^−1 at radiation-mode while maintaining a high resistivity of (1.28 ± 0.003) × 10^12 Ω cm at dark-mode due to influence of dense π-π overlaps and high-energy L1 level. Therefore, 4HPA detectors exhibit the record spectra detection of charged particles among their organic counterparts, with energy resolution of 36%, (μτ)e of (4.91 ± 0.07) × 10^−5 cm^2 V^−1, and detection time down to 3 ms. These detectors also show high X-ray detection sensitivity of 16,612 µC Gy_air^−1 cm^−3, detection limit of 20 nGy_air s^−1, and long-term stability after 690 Gy_air irradiation.