Broadband Radiative Cooling and Decoration for Passively Dissipated Portable Electronic Devices by Aperiodic Photonic Multilayers

Broadband radiative cooling and decoration for passively dissipated portable electronic devices by an aperiodic photonic multilayer structure is proposed theoretically. The designed optical structure can strongly emit in the infrared region from 6.9 to 40 mu m within the blackbody radiation spectrum of electronic devices. Its emission spectrum exhibits good uniformity across different incident angles, enhancing the cooling performance. At an ambient temperature of 20 degrees C, the designed broadband radiative cooler can produce a net cooling power of 46.88 W m(-2), 65.95% higher than pure silica of the same thickness. At a typical junction temperature of 90 degrees C allowed by the microprocessor die, the net cooling power reaches 239.55 W m(-2), still with an 18.21% improvement over pure silica glass. In the visible regime, the designed structure displays a low uniformity in the reflection spectrum, producing an elegant color shift from the translucent gray color of normal direction to the silver and highly reflective look at a grazing angle. These results can be useful in future exterior and thermal designs of portable electronic devices.