Thermal Properties of CsPbBr3 and Cs2AgBiBr6

Ahmed Kadid^a^,^b, Thomas Riedl^a^,^b, Ralf Heiderhoff^a^,^b, Maximilian Schiffer^a^,^b, Cedric Kreusel^a^,^b, Tobias Haeger^a^,^b, Helen Grüninger^e, Fatemeh Haddadi Barzoki^e, Markus Griesbach^f, Björn Beele^g, Adam Slabon^b^,^g, Detlef Rogalla^c, Christian Hess^b^,^d

^aInstitute of Electronic Devices, University of Wuppertal, Wuppertal, Germany

^bWuppertal Center for Smart Materials & Systems, University of Wuppertal, Wuppertal, Germany

^cRUBION Ruhr-University Bochum, Bochum, Germany

^dSchool of Mathematics and Natural Sciences, University of Wuppertal, Wuppertal, Germany

^eInorganic Chemistry and Bavarian Centre for Battery Technology (BayBatt), University of Bayreuth, Bayreuth, Germany

^fSoft Matter Optoelectronics, Bayreuth Institute of Macromolecular Research (BIMF) and Bavarian Polymer Institute (BPI), University of Bayreuth, Bayreuth, Germany

^gChair of Inorganic Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Wuppertal 42119, Germany

Proceedings of MATSUS Fall 2026 Conference (MATSUSFall26)

B5 Structure and Dynamics in Perovskites

Palma, Spain, 2026 October 26th - 30th

Organizer: Milos Dubajic

Poster, Ahmed Kadid, 505
Publication date: 22nd July 2026

CsPbBr₃ and Cs₂AgBiBr₆are promising all-inorganic halide-perovskites combining good stability with attractive optoelectronic properties for LEDs, Lasers or X-ray/radiation detectors. However, their specific thermal properties can hinder heat dissipation and promote local heat accumulation. Reliable knowledge of their thermal conductivity (λ), thermal diffusivity (a), and molar heat capacity (c_mol) is therefore essential for understanding heat transport and for developing effective thermal-management strategies. Yet, reported thermal properties remain highly scattered, especially for CsPbBr₃, where structural phase transitions may have an additional impact. We therefore conducted a comparative study of their thermal properties using various thermal measurement techniques.

λ, a, and c_mol were initially determined for Cs₂AgBiBr₆ and CsPbBr₃ thin films, single crystals, and powders by Scanning Thermal Microscopy using the 3w-method. For CsPbBr₃, a detailed temperature-dependent study was performed from 20 to 150 °C to resolve the thermal response across the orthorhombic–tetragonal–cubic phase transitions, whereas Cs₂AgBiBr₆was characterized in its cubic phase. The results reveal to the best of our knowledge, the first experimental determination of thermal diffusivity of 0.77 mm²/s for Cs₂AgBiBr₆, with a thermal conductivity of 1.16 W/(m·K), higher than most theoretical predictions, with c_mol close to the Dulong–Petit limit. For CsPbBr₃, λ and a show a notable decrease through the tetragonal phase (0.43 W/(m·K) to 0.28 W/(m·K), 0.38 mm²/s to 0.20 mm²/s), followed by a recovery in the cubic phase (0.53 W/(m·K), 0.34 mm²/s), which is a trend that has not been reported so far. Furthermore, in the cubic phase c_mol(T) reaches a value of 20 R, exceeding the Dulong-Petit limit of 15 R, which is attributed to the pronounced anharmonicity associated with this material. We confirmed this anomalous result by Laser Flash Analysis on single crystals and by classical Calorimetry on powder samples, supporting its validity as an intrinsic property of CsPbBr₃. Our results provide reliable thermal data for understanding heat dissipation in perovskites and for developing devices with improved thermal stability, and more reliable operation.

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