Low-dimensional perovskite halides have shown a great potential as X-ray detection materials because of efficient exciton emissions originating from strongly spatially localized charge carriers. Nonetheless, most of them have a scintillation yield far below their theoretical limits. Here, it is found that the harvesting efficiency of produced charge carriers can be significantly enhanced via a small amount of In+ doping in these highly localized structures. A bright and sensitive zero-dimensional Cs3Cu2I5:In+ halide with efficient and tunable dual emission is reported. The radio-luminescence emission of Cs3Cu2I5:In+ crystals under X-ray excitation consists of a self-trapped exciton emission at 460 nm and an In+-related emission at 620 nm at room temperature. As a result, a remarkable X-ray imaging resolution of 18 line pairs mm–1 is demonstrated, which is so far a record resolution for single crystal perovskite-based flat-panel detectors.
X-ray 2D-spatial images of the test-pattern plate based on the undoped (left) and 0.2% In doped (right) Cs3Cu2I5 single crystals.