Self‐Healing Cs₃Bi₂Br₃I₆ Perovskite Wafers for X‐Ray Detection

Abstract

Self-healing of defects imposed by external stimuli such as high energy radiation is a possibility to sustain the operational lifetime of electronic devices such as radiation detectors. Cs 3 Bi 2 Br 3 I 6 polycrystalline wafers are introduced here as novel X-ray detector material, which not only guarantees a high X-ray stopping power due to its composition with elements with high atomic numbers, but also outperforms other Bi-based semiconductors in respect to detector parameters such as detection limit, transient behavior, or dark current. The polycrystalline wafers represent a size scalable technology suitable for future integration in imager devices for medical applications. Most astonishingly, aging of these wafer-based devices results in an overall improvement of the detector performance-dark currents are reduced, photocurrents are increased, and one of the most problematic properties of X-ray detectors, the base line drift is reduced by orders of magnitude. These aging induced improvements indicate self-healing effects which are shown to result from recrystallization. Optimized synthetic conditions also improve the as prepared X-ray detectors; however, the aged device outperforms all others. Thus, self-healing acts in Cs 3 Bi 2 Br 3 I 6 as an optimization tool, which is certainly not restricted to this single compound, it is expected to be beneficial also for many further polycrystalline ionic semiconductors.

Inch-size Cs3Bi2I9 polycrystalline wafers with near-intrinsic properties for ultralow-detection-limit X-ray detection

“…Furthermore, the mt product was also estimated by fitting the current response under X-ray photons and found to be 1.08 Â 10 À4 cm 2 V À1 (seen in Fig. S3, ESI †), which is comparable to the values of most low-dimensional perovskite single crystals and polycrystals 3,44,45 (e.g., 4.43 Â 10 À4 cm 2 V À1 for the (BDA)PbI 4 single crystal, 42 5.1 Â 10 À4 cm 2 V À1 for the (F-PEA) 2 PbI 4 single crystal, 48 2 Â 10 À4 cm 2 V À1 for the MAPbI 3 wafer, 12 4.6 Â 10 À5 cm 2 V À1 for the MA 3 Bi 2 I 9 wafer, 22 3.6 Â 10 À5 cm 2 V À1 for the Cs 3 Bi 2 Br 3 I 6 wafer, 49 ).…”

“…S3, ESI†), which is comparable to the values of most low-dimensional perovskite single crystals and polycrystals 3,44,45 ( e.g. , 4.43 × 10 −4 cm 2 V −1 for the (BDA)PbI 4 single crystal, 42 5.1 × 10 −4 cm 2 V −1 for the (F-PEA) 2 PbI 4 single crystal, 48 2 × 10 −4 cm 2 V −1 for the MAPbI 3 wafer, 12 4.6 × 10 −5 cm 2 V −1 for the MA 3 Bi 2 I 9 wafer, 22 3.6 × 10 −5 cm 2 V −1 for the Cs 3 Bi 2 Br 3 I 6 wafer, 49 and 8.5 × 10 −5 cm 2 V −1 for Cs 2 AgBiBr 6 /(C 38 H 34 P 2 )MnBr 4 50 ).…”

Thick-junction perovskite X-ray detectors: processing and optoelectronic considerations

“…To address this issue, solution-processed perovskite micro-crystals/powders are often employed as starting structures to be pressed for the fabrication of thick films and wafers. 7 b ,16 In 2017, Shrestha et al reported on high-performance direct X-ray detectors based on sintered MAPbI 3 perovskite wafers (Fig. 2d).…”

Asymmetric Metal Halide Film With Suppressed Leakage Current for High Sensitive X-Ray Detection and Imaging

“…It should be emphasized that large on-off ratio is 161 an important parameter for an X-ray detector. [26] Because if 162 the detector has an ideal on-off ratio, but the photocurrent is 163 too small for the external readout circuit to achieve efficient 164 collection, the signal can simply be amplified by an external 165 amplifier. In contrast, this method appears to be infeasible if 166 the device has a poor on-off ratio.…”