Near-field thermophotovoltaics for efficient heat to electricity conversion at high power density

Rohith Mittapally; Byungjun Lee; Linxiao Zhu; Amin Reihani; Ju Won Lim; Dejiu Fan; Stephen R Forrest; Pramod Reddy; Edgar Meyhofer

doi:10.1038/s41467-021-24587-7

Near-field thermophotovoltaics for efficient heat to electricity conversion at high power density

Nat Commun. 2021 Jul 16;12(1):4364. doi: 10.1038/s41467-021-24587-7.

Authors

Rohith Mittapally^#¹, Byungjun Lee^#², Linxiao Zhu³, Amin Reihani¹, Ju Won Lim⁴, Dejiu Fan², Stephen R Forrest^{5

6

7}, Pramod Reddy^{8

9

10}, Edgar Meyhofer^{11

12}

Affiliations

¹ Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.
² Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA.
³ Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA, USA.
⁴ Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA.
⁵ Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA. stevefor@umich.edu.
⁶ Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA. stevefor@umich.edu.
⁷ Department of Physics, University of Michigan, Ann Arbor, MI, USA. stevefor@umich.edu.
⁸ Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA. pramodr@umich.edu.
⁹ Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA. pramodr@umich.edu.
¹⁰ Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA. pramodr@umich.edu.
¹¹ Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA. meyhofer@umich.edu.
¹² Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA. meyhofer@umich.edu.

^# Contributed equally.

Abstract

Thermophotovoltaic approaches that take advantage of near-field evanescent modes are being actively explored due to their potential for high-power density and high-efficiency energy conversion. However, progress towards functional near-field thermophotovoltaic devices has been limited by challenges in creating thermally robust planar emitters and photovoltaic cells designed for near-field thermal radiation. Here, we demonstrate record power densities of ~5 kW/m² at an efficiency of 6.8%, where the efficiency of the system is defined as the ratio of the electrical power output of the PV cell to the radiative heat transfer from the emitter to the PV cell. This was accomplished by developing novel emitter devices that can sustain temperatures as high as 1270 K and positioning them into the near-field (<100 nm) of custom-fabricated InGaAs-based thin film photovoltaic cells. In addition to demonstrating efficient heat-to-electricity conversion at high power density, we report the performance of thermophotovoltaic devices across a range of emitter temperatures (~800 K-1270 K) and gap sizes (70 nm-7 µm). The methods and insights achieved in this work represent a critical step towards understanding the fundamental principles of harvesting thermal energy in the near-field.

Abstract

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