RESUMEN
The perovskite solar cell (PSC) has the benefits of flexibility, inexpensiveness, and high efficiency, and has important prospective applications. However, serious optical losing and low solar energy-utilizing efficiency remain a challenge for the ultra-thin PSCs because of the interface reflection of traditional planar structure. In this study, a hierarchical pore structure with a confined resonant mode is introduced and optimized by electromagnetic theory to improve the solar energy absorbing and utilizing efficiency of ultra-thin PSCs. The large pores in the top layer that support a whispering gallery mode can focus and guide the incident light into the solar cell. The small pores in the bottom layer enable backward scattering of the unabsorbed light and can improve the effective absorption of active layer. The finite-difference time-domain method is employed to optimize the geometric parameters of hierarchical pore structure to improve the light absorption of PSCs. The proposed resonant hierarchical pore structure can greatly improve sunlight absorption of ultra-thin PSCs, and the effective light absorption and photocurrent of PSCs with a hierarchical pore structure is 20.7% higher than that of PSCs with traditional planar structure. This work can offer a beneficial guideline for improving solar energy utilizing efficiency of various thin-film solar cells.
RESUMEN
The highly reflective solar radiation of passive daytime radiative cooling (PDRC) increases heating energy consumption in the cold winter. Inspired by the temperature-adaptive skin color of chameleon, we efficiently combine temperature-adaptive solar absorption and PDRC technology to achieve "warm in winter and cool in summer". The temperature-adaptive radiative cooling coating (TARCC) with color variability is designed and fabricated, achieving 41% visible light regulation capability. Comprehensive seasonal outdoor tests confirm the reliability of the TARCC: in summer, the TARCC exhibits high solar reflectance (â¼93%) and atmospheric transmission window emittance (â¼94%), resulting in a 6.5 K subambient temperature. In the winter, the TARCC's dark color strongly absorbs solar radiation, resulting in a 4.3 K temperature rise. Compared with PDRC coatings, the TARCC can save up to 20% of annual energy in midlatitude regions and increase suitable human hours by 55%. With its low cost, easy preparation, and simple construction, the TARCC shows promise for achieving sustainable and comfortable indoor environments.
RESUMEN
Radiative cooling is a passive cooling method that does not consume additional energy and has broad application prospects. In recent studies, the surface microstructure was found to have a significant influence on improving the emissivity in infrared spectra for radiative cooling. Accordingly, in this paper, an innovative wrinkled surface microstructure without any periodicity is proposed for enhancing the infrared spectral performance of radiative cooling. The effects of the height and number of wrinkles as well as the radius and volume fraction of particles on the infrared spectral performance of radiative cooling are investigated. The radiative cooling performances of the plane, pyramid, moth-eye, and wrinkled microstructures are comparatively investigated using the finite-difference time-domain (FDTD) method. The results show that the mean emissivity of innovative radiative cooling films with the wrinkled surface microstructure reaches 99.58% in the "atmospheric window" wavelength range. The mean emissivity of the wrinkled microstructure is improved by 19%, 22.16%, and 8.41% over those of the plane, pyramid, and moth-eye microstructures, respectively. This indicates that the wrinkled microstructure exhibits a better performance for radiative cooling than single periodic surface microstructures. Furthermore, the wrinkled microstructure has no periodicity so it has low production cost, which makes it possible to replace other periodic surface microstructures.
