High-Sensitivity Remote Radiation Detection Enabled by CsPbBr3 Quantum-Dot-Doped Polymer–Silica Fiber with Core-Emitting and Cladding-Dominated Transmission

Abstract Metal halide perovskite quantum dots (PQDs), particularly CsPbBr3 QDs, are promising luminescent materials for radiation detection owing to their strong radiation absorption and high photoluminescence efficiency. However, the spectral overlap between absorption and emission can cause cumulative reabsorption losses during propagation, limiting efficient remote signal delivery. Here, a CsPbBr3 QDs-doped polymer-core/silica-cladding fiber (QPSF) was fabricated under ambient conditions using an improved capillary-filling method combined with in situ photopolymerization. The fiber exhibits a core-emitting and cladding-dominated transmission behavior, in which luminescence is generated in the QDs-doped polymer core, while a fraction of the emitted light is redirected into highly oblique trajectories within the silica cladding. These trajectories maintain lower cumulative spatial overlap with the core and therefore experience reduced cumulative reabsorption and scattering losses during propagation, thereby progressively increasing their relative contribution to the collected output. The fiber exhibits linear UV responses across 265–385 nm, with a peak sensitivity of 471 mV/(μW·cm–2) at 365 nm, 26-fold higher than that of a Ce/Tb co-doped fluorescent fiber (18 mV/(μW·cm–2)), and enables reliable signal delivery through a 20 m silica multimode fiber. Under X-ray irradiation, the QPSF shows a linear dose-rate response with a detection limit of 51.39 nGy·s–1. Its collected RL output is about 108.5% and 206.6% of those of a commercial plastic scintillating fiber and a Bi4Ge3O12 crystal rod, respectively. This study provides a facile, cost-effective, and highly sensitive fiber platform for radiation sensing and real-time monitoring.