Thermal transport in metal-halide perovskite semiconductors under operating conditions

• Applicant: Dr.-Ing. Ralf Heiderhoff
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 508311353

Metal-halide perovskites are becoming more and more important in a wide range of applications due to their outstanding (opto-)electronic properties. Aside solar cells (PSCs), this family of materials also holds great promise for future applications in light emitting diodes and lasers. In a wide range of device applications, thermal management becomes increasingly important, because both lifetime and performance are influenced by temperature or temperature gradients. Thus, the analysis of thermal transport in organic–inorganic metal-halide perovskites is indispensable.Fundamental heat transport analysis of metal-halide perovskite semiconductors under operating conditions are in the core of this project. More specifically, we will focus on all-inorganic metal-halide perovskites (CsPbX3, X = Br and Cl), which are promising for light emitting devices and provide encouraging thermal stability. Our research is aimed to provide a comprehensive understanding of the thermal transport in these materials and its implications for operating devices. Hereby, thermal investigations by Scanning Near-field Thermal Microscopy (thermal conductivities, thermal diffusivities, and volumetric heat capacities) will be complemented by X-ray diffraction, Raman spectroscopy, electron backscatter diffraction, electrical characterization, and (time resolved) photoluminescence spectroscopy to get access to material properties, such as crystallinity and crystal orientation, carrier densities, mobilities, dielectric properties, diffusion lengths, and recombination rates, in these semiconductors.The studies will be carried out on thin films in dependence on temperature and film thicknesses, which can have a significant impact on the thermal, crystal, and charge transport properties. The 0D-, 2D-, and 3D-polymorphs of Cs lead halides will be evaluated in this regard. The thermal properties will be explicitly studied with respect to actively operated metal-halide perovskite devices in dependence on charge carrier/exciton concentrations. Changes in thermal properties resulting from degradation of perovskite structures due to temperature and applied electric fields will be recognized. The heat transport from metal-halide perovskites to adjacent functional layers, will be evaluated. The main goal of the project is to develop a framework that allows to complement the typically considered electro-optical description of metal-halide perovskite devices with thermal description, which would allow to predict fundamental heat transfer properties within the active perovskite layers and the interfaces to adjacent materials.We expect that the results envisaged in this project will be essential to optimize the thermal management in metal-halide perovskite devices, such as LEDs and lasers. Moreover, we foresee that other applications, such as thermoelectric devices, would likewise benefit from the insights generated in this project.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Thomas Riedl