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A nanophotonic solar thermophotovoltaic device

An Addendum to this article was published on 03 June 2015

This article has been updated


The most common approaches to generating power from sunlight are either photovoltaic, in which sunlight directly excites electron–hole pairs in a semiconductor, or solar–thermal, in which sunlight drives a mechanical heat engine. Photovoltaic power generation is intermittent and typically only exploits a portion of the solar spectrum efficiently, whereas the intrinsic irreversibilities of small heat engines make the solar–thermal approach best suited for utility-scale power plants. There is, therefore, an increasing need for hybrid technologies for solar power generation1,2. By converting sunlight into thermal emission tuned to energies directly above the photovoltaic bandgap using a hot absorber–emitter, solar thermophotovoltaics promise to leverage the benefits of both approaches: high efficiency, by harnessing the entire solar spectrum3,4,5; scalability and compactness, because of their solid-state nature; and dispatchablility, owing to the ability to store energy using thermal or chemical means6,7,8. However, efficient collection of sunlight in the absorber and spectral control in the emitter are particularly challenging at high operating temperatures. This drawback has limited previous experimental demonstrations of this approach to conversion efficiencies around or below 1% (refs 9, 10, 11). Here, we report on a full solar thermophotovoltaic device, which, thanks to the nanophotonic properties of the absorber–emitter surface, reaches experimental efficiencies of 3.2%. The device integrates a multiwalled carbon nanotube absorber and a one-dimensional Si/SiO2 photonic-crystal emitter on the same substrate, with the absorber–emitter areas optimized to tune the energy balance of the device. Our device is planar and compact and could become a viable option for high-performance solar thermophotovoltaic energy conversion.

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Figure 1: Operating principle and components of the NARO–STPV.
Figure 2: TPV characterization.
Figure 3: Performance characterization and optimization of the nanophotonic STPV device.
Figure 4: Relative improvements in efficiency and near-term predictions for NARO–STPVs.

Change history

  • 14 May 2015

    In this Letter, the scaling factor relating the optimal emitter temperature to the photovoltaic bandgap energy was approximated using Planck's distribution expressed in units of wavelength. For a discussion of scaling factors, see the Addendum in the PDF version.


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This work is supported as part of the Solid-State Solar Thermal Energy Conversion (S3TEC) Center, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under DE-FG02-09ER46577. A.L. acknowledges the support of the Martin Family Society, the MIT Energy Initiative and the National Science Foundation GRF. Y.N. acknowledges support from the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (no. 2012R1A1A1014845). The authors thank C. Wang from Lincoln Laboratory for providing the InGaAsSb cells; H. Mutha, D. Li and C.V. Thompson's group (for CNT growth); N. Miljkovic, T. Humplik, J. Sack, D. Preston and the Device Research Lab (for SEMs, experimental set-up); and D. Kraemer, M. Luckyanova, G. Chen and the Nanoengineering group (for advice).

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All authors contributed extensively to this work. A.L., D.M.B. and Y.N. envisioned and implemented the experimental studies. A.L. and D.M.B. fabricated the absorber, executed the experiments and wrote the paper. W.R.C. designed and fabricated the emitter. I.C., M.S. and E.N.W. supervised and guided the project.

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Correspondence to Evelyn N. Wang.

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The authors declare no competing financial interests.

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Lenert, A., Bierman, D., Nam, Y. et al. A nanophotonic solar thermophotovoltaic device. Nature Nanotech 9, 126–130 (2014).

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