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 × 10⁵cm s⁻¹ at “radiation-mode” while maintaining a high resistivity of (1.28 ± 0.003) × 10¹² 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%, (μt)_e of (4.91 ± 0.07) × 10⁻⁵ cm² V⁻¹, and detection time down to 3 ms. These detectors also show high X-ray detection sensitivity of 16,612 μC Gy_abs⁻¹ cm⁻³, detection of limit of 20 nGy_air s⁻¹, and long-term stability after 690 Gy_air irradiation.