Semiconductive Coordination Polymer with Multi-Channel Charge Transfer for High-Performance Direct X-ray Detection

Abstract

Coordination polymers (CPs) are promising for direct X-ray detection and imaging owing to higher designability and outstanding stability, however, it remains a challenge to achieve highly X-ray detection performance, particularly both high sensitivity and low detection limit at the same operating voltage. Herein, we construct a new conjugated CP {[Co(BPTTz)(DIPA)] ⋅ DMA}_n (1, BPTTz=2,5-bis(pyridine-4-yl)thiazolo[5,4-d]thiazole, H₂DIPA=2,5-diiodoterephthalic acid, DMA=N, N’-dimethylacetamide), with multi-channel charge transfer by regulating the linker mediated electronic-state, which reduces carrier losses resulting from recombination or quenching, enhances the efficiency of charge separation and transfer, thus further optimizes X-ray detection performance. The semiconductor prepared based on this strategy achieves record values including the highest mobility-lifetime product (μτ, 8.05×10⁻³ cm² V⁻¹) and the lowest detectable X-ray dose rate (128 nGy_air S⁻¹, 35 V) among CP-based direct radiation detectors, as well as a high sensitivity (172 μC Gy_air⁻¹ cm⁻², 35 V) at the same operating voltage. This detector shows excellent long-time air stability under ambient conditions for over three months and operational stability. These findings demonstrate a rational structural design method to enhance the photoelectronic efficiency and stability of semiconductive CPs.