Study On Polarization-Resolved Photodetectors Based On Chiral Two-Dimensional Perovskites

The polarization of light reflects multiple physical information of matter.Therefore,the detection technology of polarization states of light is of great importance in the information era.However,conventional polarization-resolved photodetectors often rely on the optical medium with a specific structure,which is complicated to prepare and is not conducive to integration.Moreover,emerging polarization-resolved photodetectors based on material intrinsic anisotropic structures focus more on the detection of linearly polarized light.Therefore,exploring new materials with circular polarized light resolution will provide new opportunities for the development of polarization-resolved photodetectors.Chiral two-dimensional（2D）organic-inorganic hybrid perovskites have intrinsic chirality and optical anisotropy,which leads to the potential to resolve both circularly polarized light and linearly polarized light.In addition,chiral 2D perovskites have excellent optoelectronic properties such as high optical absorption coefficient,long carrier diffusion length,and low defect density,which are favorable for their applications in optoelectronic devices.In this dissertation,we propose the preparation of chiral 2D perovskites by solution cooling crystallization method,and systematically study the linear dichroism and circular polarization optical properties of chiral 2D perovskites.Utilizing the characteristics of polarization optical properties in chiral 2D perovskites,the filterless on-chip polarization-resolved photodetectors were fabricated.The polarization-resolved photodetectors can directly detect the polarization states of light,and sucessfully address the drawbacks of current polarization-resolved photodetectors such as complicated preparation and difficult integration.Specific contents include:（1）Chiral 2D perovskite crystals were prepared,and then their basic structure and optical properties were characterized.A simple solution cooling crystallization method was used to synthesize chiral/non-chiral perovskite crystals.The good crystallinity of synthesized chiral/non-chiral perovskites was proved by scanning electron microscope,X-ray diffraction,absorption spectroscopy,and photoluminescence spectroscopy.And the successful introduction of chirality from organic ligands into chiral perovskites was certificated by circular dichroism spectroscopy.（2）The optical properties of different crystal planes of chiral 2D perovskites were systematically investigated.The linear polarization optical properties of chiral 2D perovskite crystals were explored by combining experimental analysis and theoretical calculation.It was suggested that the photoluminescence peaks of chiral 2D perovskites originate from the optical differences between in-plane and out-of-plane excitons.The results have shown that chiral 2D perovskites have different linearly polarized light reflection and emission capabilities on each crystal plane,and the optical anisotropy can be adjusted by changing the temperature.（3）The circularly polarized optical properties of chiral 2D perovskites were studied.Circular dichroism spectroscopy and circularly polarized spectroscopy have confirmed that chiral 2D perovskites have circularly polarized light absorption and emission capabilities.The degree of the circularly polarized light photoluminescence of chiral 2D perovskites can reach up to 17.6%at 77 K,and the degree of the circularly polarized light photoluminescence can be adjusted by changing the temperature.（4）Polarization-resolved photodetectors based on chiral 2D perovskites were prepared.Based on the intrinsic chirality of chiral 2D perovskites,a circularly polarized photodetector with the highest responsivity of 0.45 A/W was prepared via stacking multilayer Mo S₂ and chiral 2D perovskite into a heterojunction to enhance the carrier extraction efficiency.Moreover,based on the chirality and optical anisotropy of chiral 2D perovskites,a reasonable measurement and a calculation model were developed to prepare a filterless on-chip full-Stokes polarimeter.The maximum responsivity of the polarimeter can reach0.136 A/W,and the average measurement errors of the Stokes parameters S₁,S₂,and S₃ are11%,7.5%,and 26%,respectively.