Charge carrier transport and recombination mechanisms in perovskite X/γ-ray detectors (SENSE)

• Applicant: Professorin Dr. Olena Maslyanchuk
• Subject Area: Experimental Condensed Matter Physics ; Theoretical Condensed Matter Physics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 546734407

X- and γ-radiation (X/γ-ray) detection and spectroscopy, and particularly semiconductor detector systems that can be operated at room temperature, are finding increasing applications in fields as diverse as national security, medicine, industrial process monitoring, astronomy, high energy physics, radioactive waste management, environmental remediation, and material characterization. Metal halide perovskite (MHP) is a new semiconductor family with great potential in various optoelectronic devices such as solar cells, light emission diodes, lasers, and X/γ-ray detectors. In addition to their adjustable energy band gap, high resistivity, large carriers’ mobility-lifetime product as well as high atomic number constituents, MHP also allow providing of low-cost and low temperature fabrication process, thereby becoming an attractive alternative to conventional semiconductors such as Si, Ge, CdTe, and CdZnTe for use in X/γ-ray detectors. However, despite the sufficient progress in the field, many fundamental questions are being still unraveled. The demonstrated perovskite detection efficiency shows a substantial lack due to charge collection losses (recombination) associated with distributions of defect densities within the perovskite bulk and its interfaces with the transport layers and/or electrical contacts. Accurate characterization of the origin, evolution, and magnitudes of these defect densities as well as understanding of peculiarities of charge transport processes taking into consideration ionic conduction are therefore of paramount importance to minimize the recombination losses in these devices. Unraveling of these fundamental physical problems and finding of the ways to their overcoming is a central scientific question of this project.Starting from the question, of how efficient perovskite bulk detectors can be manufactured with more available and less expensive technological way, this project will focus on a sequential approach: (i) synthesis, characterization, and adjustment of properties of MHP single crystals and polycrystalline wafers pressed from mechanochemical ball-milling synthesized powder, suitable for the fabrication of effective X/γ-ray detectors; (ii) fabrication of ohmic-type and Schottky-type detectors; (iii) study and modelling of the charge carrier dynamics; (iv) functional testing to evaluate performance and stability of the detectors.This characterization strategy will stimulate the most prominent perovskite properties and device architectures which provide modification pathways to achieve new high-performance and stable inorganic and hybrid perovskite X/γ-ray detectors based on solution grown single crystal and polycrystalline wafers.

• DFG Programme: WBP Position