Ultra-thin image sensors are extremely promising and in-demand devices for creating cameras for different electromagnetic radiation ranges from gamma- and x-ray radiation down to UV-Vis-IR image detectors. Among the semiconductor materials suitable for creating such optoelectronic devices, halide perovskites have become the focus of research in recent years. These new photonics materials combine a number of unique properties: 1) Cheap solution synthesis enabling many different device manufacturing strategies. 2) Defect tolerance, leading to outstanding devices characteristics even in the presence of impurities and defects. 3) The direct-gap semiconductor nature of most perovskites, which leads to excellent possibilities for detecting light. 4) The large atomic mass of the constituent elements allowing for effective absorption of gamma- and X-ray radiation. 5) Capabilities for customization of the composition and dimensionality of the crystal structure to meet specific devices requirements.
Within the frame of this joint project, we plan to develop cooperation between SPbU and HUST scientific groups to solve interdisciplinary problems at the intersection of physics, chemistry, materials science and nanotechnology for synthesis, understanding basic properties and fabrication of imaging devices based on 2D halide perovskites.
The SPbU group under the supervision of Dr. Yury Kapitonov is one of the leading groups in Russia in the field of fundamental optical properties of halide perovskites (>12 Q1-publications in this topic in last 5 years). As a starting point for research, it is supposed to study ultrathin (mono- and few-layer) single crystals of 2D perovskites with butylammonium (BA+) cations acting as a spacer, such as (BA)2PbI4 (n=1) and n>1 members with methylammonium (MA+) perovskitizer cations. Exfoliation will be used to make these ultra-thin specimens. Next, the samples will be studied using reflectance, transmission, and photoluminescence micro-spectroscopy at cryogenic temperatures (4 to 300 K) to determine fundamental optical properties associated with the presence of exciton resonance in these direct-gap semiconductors. The data available in the literature on this issue are fragmentary, and a coherent picture of the mechanisms of excitonic absorption and emission in these materials has not yet been established. The obtained data on the features of the optical properties of 2D perovskites in ultrathin form will be of both interest for this field of research and will serve as a starting point for the development of imaging devices based on them later in the project.
The HUST group is leading by Prof. Yuan Li. The groupbeen engaged in the research of two-dimensional perovskite materials for photodetector and image sensing devices for a long time.We have published over 80 academic papers in internationally renowned academic journals such as Chem. Rev., Adv. Mater., Adv. Funct. Mater., ACS Nano, Nano Lett., etc. In this joint project, the HUST group will mainly take the responsivity of developing high-performance photodetector and image sensor based on the evolution of high-quality 2D perovskites from the SPbU group. The standard photolithography process will be used to construct transistor photodetectors, and the performance parameters of the devices such as spectral response, responsivity, response time/recovery time, signal-to-noise ratio, etc. are tested. The detectors will be further integrated and packaged to achieve high-quality preparation of an array of imaging devices with different pixel sizes and dimensions. The key indicators of the device's photoelectric conversion efficiency, imaging speed, image resolution, etc. are characterized to achieve high-quality image sensing functions.
