AVS 63rd International Symposium & Exhibition
    Electronic Materials and Photonics Monday Sessions
       Session EM-MoM

Paper EM-MoM6
Fabrication of Nanosphere-Based Disordered Coatings for Radiative Cooling under Direct Sunlight

Monday, November 7, 2016, 10:00 am, Room 102B

Session: Advances in Photonics
Presenter: Sarun Atiganyanun, University of New Mexico
Authors: S. Atiganyanun, University of New Mexico
S.E. Han, University of New Mexico
S.M. Han, University of New Mexico
Correspondent: Click to Email
In this study, we investigate a facile fabrication of coatings made of silica nanosphere-based disordered structures via evaporation coating and air atomization coating. In both methods, silica nanospheres with a diameter of ~900 nm are dispersed in a water or methanol solution, where the sphere size can be further tuned. The colloidal stability is then disrupted by dissolving salt in the solution. In the evaporation coating, the bulk solution is confined in a substrate and is let to evaporate. In the atomization coating, the solution is atomized by a spray nozzle, and resulting droplets are deposited onto a substrate. Scanning electron microscopy images and subsequent autocorrelation analyses show that the resulting structures are disordered without short- or long-range order. Transmission measurement also indicates that the structures have a short transport photon mean free path of approximately 4-8 μm. These results suggest strong photon scattering properties in the visible region, while providing a strong emission window in 8 to 13 μm range. Such films would enable potential applications in radiative cooling. To investigate this aspect, a computational model is used to calculate the cooling power of the coatings under direct sunlight. The model predicts that the disordered coating with 200 μm thickness has a cooling power of ~250 W/m2 at 27ºC and could reduce the temperature of the sample under a direct sunlight by approximately 37ºC below the ambient temperature. We will further discuss our experimental measurements in this presentation.