Perovskites have a wide range of possible applications, e.g., in solar cells, LEDs, lasers, and photodetectors. Single crystals of metal halide perovskites (MHPs), such as methylammonium lead tribromide (MAPbBr₃), could be used for the detection of high‐energy γ-radiation via photocurrent measurements. However, the volume of laboratory‐grown MHP single crystals for γ‐ray detection has been limited to ca. 1.2 cm³ so far. Methods for growing larger single crystals could allow the implementation of MHPs in high‐energy radiation detection.

Pavao Andričević, László Forró, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland, and colleagues have developed the so-called “oriented crystal‐crystal intergrowth” method, which allowed the team to create solution‐grown MAPbBr₃ crystals with a volume and mass of over 1,000 cm³ and 3 kg, respectively. First, the team grew small MAPbBr₃ single crystals with sizes of ca. 5 mm by gradually increasing the temperature of a room-temperature saturated MAPbBr₃ solution. Then, these small crystals were attached to a cotton string and used as seed crystals to grow larger MAPbBr₃ single crystals. The resulting crystals were used as building blocks for the desired large single crystal: They were aligned side‐by‐side along with their facets (pictured), immersed in a solution of MAPbBr₃, and fused together while slowly increasing the temperature of the solution.

The team used the resulting MAPbBr₃ single crystals together with various carbon electrodes for γ‐ray detection from a ⁶⁰Co source. They found that the measured dose rates show a good correlation with commercially available measuring devices. The perovskite has a high γ-ray tolerance, and the devices show operational stability for over 100 h.

• Kilogram‐Scale Crystallogenesis of Halide Perovskites for Gamma‐Rays Dose Rate Measurements,
  Pavao Andričević, Pavel Frajtag, Vincent Pierre Lamirand, Andreas Pautz, Márton Kollár, Bálint Náfrádi, Andrzej Sienkiewicz, Tonko Garma, László Forró, Endre Horváth,
  Adv. Sci. 2020, 8, 2001882.
  https://doi.org/10.1002/advs.202001882