CAREER: Enabling Light-Driven Thermodynamic Cycles

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2) As an alternative to conventional mechanical systems, the process of light (photon) emission and absorption can be used for refrigeration and conversion of heat into electricity. This is a solid-state approach that can offer significant advantages in applications where size, cost, speed, and reliability are important, such as renewable energy, solid-state refrigeration, and distributed power generation. Though promising, the approach requires exceptional control over light emission and absorption processes to achieve high performance. The goal of this project is to address this technological gap by developing an innovative device, consisting of Inter-Digitated Emitters and Absorbers of Light (IDEAL), that virtually eliminates photon loss and thus bridges the gap relative to theoretical limits. Such devices can leapfrog the limitations of current mechanical processes and enable a societal transition to a clean and sustainable energy system. This project will also introduce the principles of optical thermodynamics to under-resourced schools in metro Detroit and offer workshops that demystify graduate school, thus expanding STEM opportunities. With advances in manufacturing enabling high-quality photovoltaic materials, the key barrier to high performance in thermo-photonic devices has become the ability to selectively absorb above-bandgap photons, suppress parasitic absorption of luminescent photons, and maintain efficiency at elevated power densities. These shortcomings have resulted in significant efficiency losses relative to thermodynamic limits. This project will address this gap by developing an innovative device concept, named IDEAL, that features interdigitated photovoltaic absorbers and thermal/luminescent emitters. The novelty of the IDEAL approach is that it (1) creates lines of symmetry that act as perfect broadband reflectors and (2) enhances the power density while preserving efficiency. The project will implement the concept in two model material systems to test its generality and map out the coupling between thermal and optoelectronic properties to provide design rules for high performance. The expected result is almost an order of magnitude reduction in photon loss probabilities compared to current performance in photovoltaics and light-emitting diodes, which will yield large gains in the thermodynamic efficiency of thermophotovoltaic power generation and electroluminescent refrigeration. The IDEAL geometry has the added benefit of potentially enabling power densities that are only accessible to near-field approaches. 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.