CAREER: Advancing intelligent circular spectropolarimeter with chiral perovskite heterostructures

Nontechnical description: Light carries far more information than brightness alone. Its color and polarization contain valuable signals used in secure communication, imaging, and sensing technologies. However, systems capable of analyzing richer optical information—such as identifying circular polarization and spectrum simultaneously—are typically bulky, slow, and incompatible with modern microelectronics. Developing compact devices that directly decode complex optical signals is therefore an important challenge. This project addresses this need by developing circular spectropolarimeters based on chiral hybrid perovskites, an emerging class of semiconductor materials whose structure lacks mirror symmetry—similar to our left and right hands—and enables directional control of electron spin. By investigating how the handedness and wavelength of light influence spin-selective charge generation and transport in these materials, this research will establish a new scientific framework for translating complex optical information directly into characteristic electrical readouts. The resulting ultracompact device platform will advance applications such as secure optical communication, biological sensing, and imaging technologies, while the fundamental insights generated by this research will contribute to a broader range of disciplines, including photonics, chemistry, and quantum information science. Education and outreach are integrated into this project through K-12 summer workshops, partnerships with local schools, and project-based modules incorporated into undergraduate coursework. These efforts will broaden participation in STEM fields and help prepare the next-generation workforce in advanced semiconductor technologies. Technical Description: This CAREER project develops compact, scalable photodetectors capable of simultaneously resolving spectral information and circular polarization through electrically encoded signatures using chiral hybrid organic-inorganic perovskites (HOIPs). Among solution-processed semiconductor platforms, chiral HOIPs are uniquely suitable for this application due to their strong spin-orbit coupling and chirality-induced spin selectivity, which directly couple optical excitation to spin polarization and charge transport behavior. The central hypothesis is that CPL induces helicity-dependent spin polarization in chiral HOIPs, producing spin-selective photocurrent, while wavelength-dependent absorption profiles govern carrier generation depth and bias-controlled extraction, jointly encoding polarization and spectral information into multidimensional electrical signatures. By training a neural network to decode these bias-resolved signatures, both the degree of circular polarization and spectral content can be reconstructed from a single voltage sweep without mechanical or optical filtering components. To realize this vision, the project integrates spin physics, optical field modulation, and device engineering into the design of chiral optoelectronics. The specific approaches include: 1) designing HOIP heterostructures to enhance helicity-dependent spin polarization and maximize directional spin-to-charge conversion efficiency under broadband CPL excitation; 2) tailoring internal optical field distributions to control wavelength-dependent carrier generation depth and extraction pathways; and 3) developing device architectures to enhance signal dimensionality and separability across optical inputs. These designs establish a computational platform for rapid spectropolarimetric photodetection using solution-processed materials, while advancing fundamental understanding of spin generation, transport, and conversion in chiral HOIPs. These insights will be transferable to other chiral material systems, such as chiral organic compounds and inorganic assemblies, and will define general design principles for optoelectronic and spintronic devices. This award reflects NSF's statutory mission and has been de NSF Award ID: 2542866 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Mengxia Liu | Institution: Yale University, NEW HAVEN, CT | Award Amount: $575,000 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2542866 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2542866.html