Thin Film Air-Bridge Thermal Photovoltaic Cells—Approaching the Efficiency Limit

The combination of non-destructive epitaxial liftoff and cold weld bonding of III-V materials developed in our laboratory has opened the way to realizing a variety of thin film inorganic semiconductor devices that can serve applications that have heretofore not been accessible to conventional semiconductors.[1] For example, we have demonstrated devices as diverse as cylindrical and hemispherical imagers, the latter of which that undergo a topological transformation during fabrication,[2] and more recently, extremely high efficiency InGaAsP and InGaAs thermal photovoltaics that employ exceptionally long air-bridges where the very thin active semiconductor is suspended between gold pillars.[3, 4] These cells result in almost perfect photon utilization given the very high reflectivity of the air bridge construction. In this talk we will discuss advances and state of the art in both single junction and tandem thin film air bridge thermal photovoltaic cells and their potential use in widespread thermal energy storage.<br/><br/>[1] K. Lee, J. D. Zimmerman, T. W. Hughes, and S. R. Forrest, "Non-Destructive Wafer Recycling for Low-Cost Thin-Film Flexible Optoelectronics," <i>Adv. Functional Mater., </i>vol. 24, p. 4284, 2014.<br/>[2] D. Fan, B. Lee, C. Coburn, and S. R. Forrest, "From 2D to 3D: Strain-and elongation-free topological transformations of optoelectronic circuits," <i>Proc. National Academy of Sciences, </i>p. 201813001, 2019.<br/>[3] D. Fan, T. Burger, S. McSherry, B. Lee, A. J. Lenert, and S. R. Forrest, "Nearly perfect photon utilization in an air-bridge thermophotovoltaic cell," <i>Nature, </i>vol. 586, p. 237, 2020.<br/>[4] B. Roy-Layinde, J. Lim, C. Arneson, S. R. Forrest, and A. Lenert, "High-efficiency air-bridge thermophotovoltaic cells," <i>Joule, </i>2024.