Repurposing low-dimensional hybrid perovskites for the detection of low-energy photons

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Nontechnical DescriptionMetal halide perovskites are a new class of solution-processible semiconductors. These are hybrid materials, using a variety of organic and inorganic components as building blocks. This allows tuning of their optical, electrical and thermal-transport properties for the desired use. They have shown particular promise for use in applications such as solar energy harvesting, displays, and solid-state lighting. This project focuses on understanding the fundamental properties of a sub-class of metal halide perovskites. These two-dimensional (2D) materials consist of interpenetrating organic and inorganic layers arranged by design. The team will study the structure and optical properties of 2D perovskites to gain insight into what governs their thermal conductivity and how charge carriers interact with the crystal lattice. Understanding the unique properties of 2D perovskites will help to evaluate their potential for device applications and accelerate their adoption into advanced device technologies. In particular, the goal is to establish 2D perovskites for detection of infrared led, which has traditionally relied on vapor-phase grown semiconductors that are expensive to process. The project will train graduate and undergraduate students in synthesis and characterization of novel semiconductors, including building and modifying instrumentation.Technical DescriptionThe ability to detect light is crucial in areas ranging from photography and bio-imaging to materials characterization and precision metrology. The difficulty of light detection depends on the energy carried by each photon, the smallest energy quanta of light. While silicon-based detectors are mature and sensitive, the detection of photons whose energies fall below the bandgap of silicon is generally more challenging. The goal of this project is to understand how the thermal conductivity and exciton-lattice interactions of two-dimensional metal halide perovskites can be influenced and ultimately controlled through the type of organic spacers, the intentionally introduced stacking disorders, and the connectivity mode of the inorganic octahedral layers. A variety of techniques, including time-resolved vibrational-pump visible-probe spectroscopy, pump-probe optical imaging, and synchrotron x-ray diffraction, will be employed to characterize the structure-property relationships of judiciously chosen two-dimensional perovskite compositions. The understanding gained will provide a fundamental understanding of the thermal and optical properties of these solution-processable materials and establish the knowledge base to use them for detecting low-energy photons in the near-infrared to the mid-infrared range.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.