What is it about?

In a thin-film solar cell, light trapping can lead to efficient absorption even when the absorbing layers are thinned down to only a few hundred nanometres. We demonstrate that placing the thin film in an optical cavity can also produce substantial changes in its total light emission rate. Moreover, in an optical cavity, the optical energy transfer can be highly efficient even if the absorber layer is extremely thin.

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Why is it important?

Our work is relevant especially for the nascent fields of electroluminescent cooling and thermophotonic energy harvesting. More generally, the results have relevance in many emerging fields utilizing thin-film technology, such as ultrathin solar cells and detectors, thin-film LEDs, and photonic power converters. One of the interesting aspects of thin films is their potential to reduce the amount of source materials required for the fabrication of photonic devices.


This work exemplifies my long journey during the last few years in the fluctuational electrodynamics modeling of multilayer thin-film devices. I was surprised to find out how much interferences modify even the total optical power emitted by thin layers, not only the power emitted to specific angles. I feel like we were only able to scratch the surface when it comes to understanding all the peculiarities from shrinking the thickness of our typical photonic devices toward and even below the wavelength of the emitted light.

Pyry Kivisaari
Aalto University

Read the Original

This page is a summary of: Resonance effects in the radiation transfer of thin-film intracavity devices, Applied Physics Letters, November 2022, American Institute of Physics, DOI: 10.1063/5.0109763.
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