Ultra‐Sensitive Neutron Detection Using Hybrid Perovskite Single Crystals With High‐Z Doping and Band‐Aligned Heterostructure

ABSTRACT Halide perovskites are novel and promising semiconductors for next‐generation direct radiation detectors due to excellent optoelectronic properties and tunable composition. Here, ultra‐sensitive neutron detectors are realized by enhancing secondary particle‐perovskite interactions and charge‐collecting efficiency via high‐Z doping, band‐aligned heterostructures, and BN neutron converters. Neutron transport Monte Carlo simulations and first‐principle calculations reveal that doping BiI 3 into MAPbBr 3 improves both energy deposition from secondary particles (mostly α ) and electronic band structure. High‐quality MAPbBr 3 single crystals with various BiI 3 ‐doping concentrations are synthesized via inverse temperature crystallization, which is used to fabricate band‐aligned heterostructure devices with optimal carrier transport layers. The devices exhibit enhanced photocurrent responses and reduced dark noises, achieving on/off ratios >1000. Under a 252 Cf radiation source, BiI 3 ‐doped devices demonstrate significant increases in net neutron‐induced current (from 50 to 1000 pA) and sensitivity (from 10 −3 to 10 −2 pA (n cm −2 s −1 ) −1 ) at a small bias voltage of 15 V. The reported sensitivity here is 10 to 100 times higher than existing perovskite‐based and most of the current response‐mode neutron detectors. Earth‐abundant materials, facile synthesis methods, polyethylene neutron mediator, and natural BN neutron conversion layer used here offer the possibility of very low‐cost, compact, and highly efficient neutron detection for nuclear safety, medical imaging, and scientific instruments.