Passive cooling of outdoor LED lights via radiative and non-radiative synergistic processes

Light emitting diodes (LEDs) are widely used in road lighting due to their high luminous efficiency and long lifetime. However, during operation, LEDs are prone to luminous efficiency decay and lifetime reduction because of the Joule heating effect. This study develops a passive cooling device by integrating an h-BN@acrylic/TiO 2 radiative cooling coating onto a conventional heat sink, enabling radiative and non-radiative synergistic heat dissipation. The device exhibits high solar reflectance (97.3%), strong mid-infrared emissivity (96.2%), and excellent non-radiative heat transfer coefficient (18.2 W m −2  K −1 ). Results demonstrate that under outdoor solar irradiance of ∼926 W m −2 , the device reduces the temperature of a 30 W LED by 8.1 ± 0.3 °C compared to a commercial LED light. After more than 3,600 h of aging tests, the LED maintained 97.9% of its initial luminous flux, exhibiting a 2.17% improvement in luminous efficiency compared to a traditional light. If applied across China’s LED road lighting network, this device potentially saves approximately 773 million kWh of electricity annually, reducing CO 2 emissions by 420,000 tons. Combining experimental and computational approaches, this work demonstrates the synergistic benefits of multimodal thermal management for high-power optoelectronic devices and offers both theoretical insights and practical strategies for achieving above-ambient cooling.