PP 2196/1: Transport of Optical Exciations in Low-Dimensional Halide Perovskites: Coulomb Effects & Structural Dynamics

The recent intense scientific efforts related to halide perovskites (HaPs) have revolutionized and invigorated the solid-state research community. The tremendous interest was fuelled by rapid advances in the performances of HaP-based photovoltaic and other optoelectronic devices. Several of the breakthroughs in the field were highly promising, considering today’s challenges in developing alternative energy sources and cost-efficient lighting applications. However, a wide array of fundamental questions remains to be addressed, especially regarding key issues associated with the interplay of optical and structural excitations. Complemented by the ongoing search for new HaPs, this motivates our scientific questions: We are interested in the microscopic nature of optical transport and how it is impacted by Coulomb interactions of the charge carriers and non-trivial lattice dynamics, towards fully exploiting the structural, electronic, and chemical tunability of HaPs. The goal of our research is to provide answers to these critical questions by studying low-dimensional HaPs from combined experimental and theoretical perspectives. We aim for obtaining a comprehensive picture of propagation and scattering of interacting charge carriers coupled to lattice vibrations across a broad range of technologically relevant scenarios in two-dimensional (2D) HaPs. The motivation underlying our focus on 2D HaPs is the possibility of an efficient tuning of the Coulomb physics and a control over structural dynamics and exciton-phonon couplings through the exceptional material flexibility of this material platform. To this end, we will explore optical transport in 2D HaPs and develop a fundamental understanding of the interplay of Coulomb effects with structural dynamics. In our project, these insights will be directly transferred to 2D HaP device development and the synthesis of novel compounds.To achieve these goals, a highly efficient feedback loop between theory, spectroscopy, synthesis, and device physics will be established. We will perform microscopic calculations of structural dynamics, study electronic and excitonic effects, conduct frontier optical spectroscopy allowing for direct monitoring of electron-hole propagation, and go all the way from addressing advanced materials synthesis to their applications in devices. The research efforts of our consortium are embedded in a broader collaborative network involving excellent theoretical and experimental partners. Our agenda addresses timely questions on the forefront of the ongoing research efforts in the field. We expect that achieving our research objectives will allow for establishing a fundamental basis to control optical excitations in HaP-based systems via exploring the interplay of optical and structural dynamics across a wide range of technologically relevant compounds. With this, we hope to develop a general framework guiding future advances in regard to hybrid semiconductors.