Extreme γ-Ray Radiation Tolerance of Spectrometer-Grade CsPbBr3 Perovskite Detectors.

The perovskite compound CsPbBr3 has recently been discovered as a promising room-temperature semiconductor radiation detector, offering an inexpensive and easy-to-manufacture alternative to the current benchmark material Cd1-x Znx Te (CZT). The performance of CsPbBr3 sensors is evaluated under harsh conditions, such as high radiation doses often found in industrial settings and extreme radiation in space. Results show minimal degradation in detector performance after exposure to 1 Mrad of Co-60 gamma radiation, with no significant change to energy resolution or hole mobility and lifetime. Additionally, many of the devices are still functional after being exposed to a 10 Mrad dose over 3 days, and those that do not survive can still be refabricated into working detectors. These results suggest that the failure mode in these devices is likely related to the interface between the electrode and material and their reaction, or the electrode itself and not the material itself. Overall, the study suggests that CsPbBr3 has high potential as a reliable and efficient radiation detector in various applications, including those involving extreme fluxes and energies of gamma-ray radiation.

Laser Scribing for Electrode Patterning of Perovskite Spectrometer-Grade CsPbBr3 Gamma-ray Detectors.

Making semiconductor radiation detectors that work at room temperature relies heavily on the deposition and pixelation of electrodes. Electrode patterning of perovskite solar cells widely implements laser scribing techniques, which is a convenient, scalable, and inexpensive technique. However, this method has not found its application in radiation detector patterning yet, and the question whether laser scribing can achieve high-quality patterns with minimum damage to a detector crystal and low interpixel cross-talk remains largely unanswered. To prove that laser scribing is a practical method for electrode patterning on perovskite CsPbBr3 detectors, we use the material to create a variety of patterns. A very low lateral leakage current (60 nA at 10 V) and high mobility-lifetime product (9.7(3) × 10-4 cm2/V) were observed between the pixel and the guard ring in tests of single-pixel devices with a separation of 200 or 100 µm between the central electrode and the guard ring. The 122 and 136 keV photopeaks in 57Co gamma-ray spectra were very well resolved with an energy resolution of up to 6.1% at 122 keV. A further reduction in gap size to 50 µm is conceivable, but more process optimization is needed.

Sr(Ag1-x Lix )2 Se2 and [Sr3 Se2 ][(Ag1-x Lix )2 Se2 ] Tunable Direct Band Gap Semiconductors.

Synthesizing solids in molten fluxes enables the rapid diffusion of soluble species at temperatures lower than in solid-state reactions, leading to crystal formation of kinetically stable compounds. In this study, we demonstrate the effectiveness of mixed hydroxide and halide fluxes in synthesizing complex Sr/Ag/Se in mixed LiOH/LiCl. We have accessed a series of two-dimensional Sr(Ag1-x Lix )2 Se2 layered phases. With increased LiOH/LiCl ratio or reaction temperature, Li partially substituted Ag to form solid solutions of Sr(Ag1-x Lix )2 Se2 with x up to 0.45. In addition, a new type of intergrowth compound [Sr3 Se2 ][(Ag1-x Lix )2 Se2 ] was synthesized upon further reaction of Sr(Ag1-x Lix )2 Se2 with SrSe. Both Sr(Ag1-x Lix )2 Se2 and [Sr3 Se2 ][(Ag1-x Lix )2 Se2 ] exhibit a direct band gap, which increases with increasing Li substitution (x). Therefore, the band gap of Sr(Ag1-x Lix )2 Se2 can be precisely tuned via fine-tuning x that is controlled by only the flux ratio and temperature.