Eco‐Friendly Transparent Silk Fibroin Radiative Cooling Film for Thermal Management of Optoelectronics

Abstract

Although transparent radiative cooling is a passive cooling strategy with practical applications and aesthetic appeal, complex manufacturing processes and the use of environmentally unfriendly thermal emitters remain latent problems. Herein, eco‐friendly transparent silk radiative cooling (TSRC) films are developed, regenerated from natural silkworm cocoons, for zero‐energy‐consumption thermal management of optoelectronic devices. These TSRC films can dissipate heat radiatively through molecular vibrations of the protein backbone and side chains, while retaining the function and appearance of the associated devices, due to their high visible transparency. Theoretical and experimental investigations revealed that the thermal emission increases rapidly upon increasing the film thickness, but slowly thereafter achieves saturation; nevertheless, the intrinsic solar absorption of silk in the ultraviolet and near‐infrared regions also grows linearly, unavoidably weakening the cooling effect. After spectroscopic optimization, the maximum cooling power during the daytime and nighttime is improved to 77.6 and 101.7 W m−2, respectively. Gratifyingly, the films have a remarkable effect on the cooling performance of electronic devices under sunlight. For example, the TSRC film provides a temperature drop of 5.1 °C for a smartphone during multitasking and charging, and 14 °C for a silicon solar panel with an improvement in the photoelectronic conversion efficiency (≈7%).

Supramolecularly Connected Armor-like Nanostructure Enables Mechanically Robust Radiative Cooling Materials

“…According to Planck's law (Figure 4b), the blackbody radiation peak of the object is the 8−13 μm, which coincides with the most important transparent bands, atmospheric window. By combining the steady state heat transfer equilibrium analysis with Planck's radiation law, 34,35 we first calculated the cooling powers of a TMCP film with the radiation temperature ranging from 0 to 40 °C. It is assumed that the nonradiative heat loss is zero and the ambient temperature is fixed at 30 °C.…”

Switchable and Tunable Radiative Cooling: Mechanisms, Applications, and Perspectives

“…Zhu et al 101 applied microfabrication to process natural silk for radiative cooling fabrics. Chen et al 102 achieved transparent radiative cooling using silk protein. It is thus expected that the use of natural materials will contribute to the sustainable development of STRC.…”

POSS/PVTMS aerogels for passive cooling and THz communication via cross-linking density regulation and nanoscale bimodal design

“…4,5 Compared with traditional cooling technology, passive daytime radiative cooling (PDRC) is emerging as an appealing cooling strategy due to zero-energy input consumption. 6–8 Because the main feature of PDRC materials is the ability to reduce the indoor heat gain from solar energy, 9 the materials should possess the capability to reflect most of the sunlight (0.3–2.5 μm wavelengths) while radiating heat to outer space through the atmospheric transparency window in the long-wave infrared region (8–13 μm wavelength) and decreasing thermal conduction to the building interior. 10,11…”