Self-hygroscopic and smart color-changing hydrogels as coolers for improving energy conversion efficiency of electronics

Phase change materials as a potential passive cooling solution is widely used to cool electronic devices, since the high temperature accompanied by the continuous operation of these electronic devices significantly affects their efficiencies and causes irreversible damage. However, there is a lack of the feedback on cooling potential and recessive failures such as ineffective cooling due to overuse. Here, we report a self-hygroscopic and smart color -changing Co@Li-PAM hydrogel, composed of polyacrylamide (PAM)-based polymer chains, H2O molecules, and functional ions including Li+, Co2+, [Co(H2O)]2+, Cl-, and Br-. It has been found that the hydrophilic porous PAM network acts as the main framework with excellent biocompatibility and reliable chemical stability, LiBr acts as the adsorbent in the PAM network to absorb water molecules in the air during electronic device downtime, and Co ions are introduced into hydrogels through coordination bonds formed with amide groups of polymer chains. The reversible transformation between [Co(H2O)6]2+ and Co2+ driven by the water content in Co@Li-PAM triggers color changes, which indicates the current heat dissipation potential of hydrogels. Applying the as -designed Co@Li-PAM hydrogel to cooling commercial polycrystalline silicon solar cells can increase its energy conversion efficiency by 1.26 % under the illumination of 1 kW m-2. This strategy is expected to provide exotic solutions for the development of electronic devices, carbon neutrality, and global sustainable development goals.

Automated summary

Phase change materials are widely used for cooling electronic devices due to their potential as passive cooling solutions. This study reports a self-hygroscopic and smart color-changing hydrogel, Co@Li-PAM, which shows promising cooling potential and can be applied in electronic devices. The hydrogel consists of a porous PAM network, LiBr adsorbents, and Co ions, with reversible color changes indicating heat dissipation potential. Applying the Co@Li-PAM hydrogel to polycrystalline silicon solar cells increases energy conversion efficiency by 1.26%. This strategy offers solutions for electronic device development, carbon neutrality, and sustainable development goals.