Low-Dimensional Chiral Perovskites for Circularly Polarized Light Detection

About This Grant

Low-Dimensional Chiral Perovskites for Circularly Polarized Light Detection Circularly polarized light (CPL) photodetectors emerge as an indispensable component in quantum computing, spin-optical communication, information processing, and remote sensing because of their capabilities of distinguishing the handedness of CPL that encodes charge carrier spin information. The state-of-the-art technologies for CPL detection are based on conventional photodetectors coupled with optical components of linear polarizer and quarter-wave plates to convert CPL to linearly polarized light. These device structures cause substantial losses of sensitivity and handedness selectivity, slows detection speed, and faces a tremendous challenge for device miniaturization and integration. Low-dimensional chiral perovskites, which are composed of corner-shared or face-shared inorganic metal halide octahedra and chiral organic cations, have emerged as promising candidates for direct CPL detection because of their tunable band gaps as well as their spin-selective high absorption coefficients and favorable charge-carrier mobilities. Despite recent progress in developing CPL photodetectors, the device performance still lags conventional photodetectors in terms of specific detectivity, dynamic response, and most importantly, the capability to distinguish the handedness of CPL. Here, the research team proposes a synergetic approach via materials innovation and device engineering to enhance chirality and charge transport/extraction, reduce dark current, and increase dynamic photoresponse, hence, to achieve highly selective, sensitive, and fast CPL detection. The success of this project will advance the fundamental knowledge of chiral semiconductors and CPL photodetectors and could lead to transformative technologies in quantum computing, spin-optical communication, and information processing. Graduate and undergraduate students will receive training in this highly interdisciplinary research project. The knowledge gained from this work will be disseminated through the outreach to local high schools and on-campus workshops for young students with hands-on experience. The objectives of this work are to conduct fundamental research through a synergetic approach from materials development to device engineering to enhance chirality and charge transport of chiral two-dimensional (2D) and one-dimensional (1D) perovskites, leading to highly selective, sensitive, and fast CPL detection. At the material level, chiral 2D and 1D perovskite thin films with tailored n-type semiconducting chiral cations will be synthesized and fabricated to allow increasing the chirality, tuning band structure and energy alignment, and enhancing charge transport. At the device level, CPL detectors will be developed based on the photodiode-type structure with hole-only, electron-only and conventional configurations and the configuration of devices will be further optimized using finite-difference time-domain (FDTD) electromagnetic simulations, transfer matrix method (TMM) optical calculations, and CHARGE solver charge transfer simulations to achieve strong selective handedness of CPL absorption in the chiral active layer and high charge generation rate, charge transfer and photocurrent density with monochromatic CPL irradiations. The designed CPL photodetectors will be fabricated, and their performance will be assessed in terms of the figures of merit of photodetectors. The device performance results will be used to guide the improvement of materials and device structures. The research team will conduct systematic material property, device photophysics and device performance studies to elucidate the material-device structure-device performance relationship of CPL photodetectors based on chiral 2D and 1D perovskites and photodiode-type structures. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.