Title: Radiative cooling of solar absorbers using a visibly transparent photonic crystal thermal blackbody

Abstract

A solar absorber, under the sun, is heated up by sunlight. In many applications, including solar cells and outdoor structures, the absorption of sunlight is intrinsic for either operational or aesthetic considerations, but the resulting heating is undesirable. Because a solar absorber by necessity faces the sky, it also naturally has radiative access to the coldness of the universe. Therefore, in these applications it would be very attractive to directly use the sky as a heat sink while preserving solar absorption properties. In this paper, we experimentally demonstrate a visibly transparent thermal blackbody, based on a silica photonic crystal. When placed on a silicon absorber under sunlight, such a blackbody preserves or even slightly enhances sunlight absorption, but reduces the temperature of the underlying silicon absorber by as much as 13 °C due to radiative cooling. Lastly, our work shows that the concept of radiative cooling can be used in combination with the utilization of sunlight, enabling new technological capabilities.

Authors:

Zhu, Linxiao ^[1]; Raman, Aaswath P. ^[2]; Fan, Shanhui ^[2]

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+ Show Author Affiliations

1. Department of Applied Physics, Stanford University, Stanford, CA 94305,
2. Ginzton Laboratory, Department of Electrical Engineering, Stanford University, Stanford, CA 94305

Publication Date:

Mon Sep 21 00:00:00 EDT 2015

Research Org.:

Stanford Univ., CA (United States)

Sponsoring Org.:

USDOE Advanced Research Projects Agency - Energy (ARPA-E); National Science Foundation (NSF)

OSTI Identifier:

1235126

Alternate Identifier(s):

OSTI ID: 1348350

Grant/Contract Number:  

AR0000316; ECS-9731293

Resource Type:

Published Article

Journal Name:

Proceedings of the National Academy of Sciences of the United States of America

Additional Journal Information:

Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Volume: 112 Journal Issue: 40; Journal ID: ISSN 0027-8424

Publisher:

Proceedings of the National Academy of Sciences

Country of Publication:

United States

Language:

English

Subject:

42 ENGINEERING; radiative cooling; thermal radiation; photonic crystal; solar absorber