Ultra‐Low Dark Current Organic–Inorganic Hybrid X‐Ray Detectors

Abstract

AbstractOrganic‐inorganic hybrid semiconductors are an emerging class of materials for direct conversion X‐ray detection due to attractive characteristics such as high sensitivity and the potential to form conformal detectors. However, existing hybrid semiconductor X‐ray detectors display dark currents that are 1000–10 000× higher than industrially relevant values of 1–10 pA mm−2. Herein, ultra‐low dark currents of <10 pA mm−2, under electric fields as high as ≈4 V µm−1, for hybrid X‐ray detectors consisting of bismuth oxide nanoparticles (for enhanced X‐ray attenuation) incorporated into an organic bulk heterojunction consisting of p‐type Poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) and n‐type [6,6]‐Phenyl C71 butyric acid methyl ester (PC70BM) are reported. Such ultra‐low dark currents are realized through the enrichment of the hole selective p‐type organic semiconductor near the anode contact. The resulting detectors demonstrate broadband X‐ray response including an exceptionally high sensitivity of ≈1.5 mC Gy−1 cm−2 and <6% variation in angular dependence response under 6 MV hard X‐rays. The above characteristics in combination with excellent dose linearity, dose rate linearity, and reproducibility over a broad energy range enable these detectors to be developed for medical and industrial applications.