We demonstrate a simple, low-cost design of a selectively emissive radiative cooler using scotch tape and aluminum foil, which can be further augmented by higher quality metal deposition methods. This do-it-yourself radiative cooler achieves solar reflectance, long wavelength infrared emittance, and optical selectivity comparable to state-of-the art designs and is experimentally demonstrated as achieving a 7°C subambient temperature drop at night for the aluminized scotch tape and an average 2°C drop under a solar illumination of 965  W  /  m² for the silvered scotch tape. In addition, an 11°C subambient temperature drop at night for the aluminized scotch tape was obtained when a convection shield was used. Detailed optical properties are presented for an ultrawide wavelength range and a ∼2π angle of emittance. Given its ease of fabrication and performance, we propose this set of materials as a control for future radiative cooling experiments and an effective radiative cooling accessory for passive cooling designs.

The principle of radiative cooling is to radiate the extra heat energy of Earth into outer space, and a lot of progress has been made in recent years. Radiative cooling is significantly affected by the air quality, and coolers reported at present only work well under a clear sky. Moreover, most of the world’s industrial cities are facing serious haze problems; thus improving the cooling performance under haze conditions needs to be addressed. We propose a water evaporation assisted radiative cooling technique, and the experimental results showed a remarkable subambient cooling of 6.4°C in daytime haze.

Conventional concentrator photovoltaics (CPV) employing two-axis tracking are generally only economically competitive with cheaper, less efficient alternatives in locations with large amounts of direct sunlight. Adding a diffuse light collector to a CPV panel in the form of a silicon back panel can potentially improve the light collection under cloudy conditions and expand the range of climates in which CPV is useful. However, to understand the performance advantages available with diffuse collection, a realistic forecasting tool to predict performance in different locations is required. We introduce a model to evaluate the annual energy yield of a hybrid CPV and Si module and compare the results with several conventional stand-alone Si and CPV modules. The advantages of including a bifacial Si panel as the diffuse collector will also be investigated.

We derive the photovoltaic conversion efficiency limit for two-terminal tandem solar cells with a perovskite top cell and silicon bottom cell with an embedded spectrum splitter. For large-bandgap top-cells, a spectrum splitter strongly enhances the efficiency because of enhanced light absorption and trapping. A Lambertian spectral splitter shows a significantly improved effect compared with a planar splitter. We find an ideal efficiency enhancement for a 500-nm thick top cell of 6% absolute for bandgaps above 1.75 eV. Vice versa, the use of a spectral splitter geometry enables the use of a thinner top cell. Using experimental parameters for perovskite cells, we show that for a top-cell bandgap of 1.77 eV a 2.7% absolute efficiency enhancement can be achieved. The calculations in this work show that integration of a spectral splitter into perovskite/silicon tandem cells for which the top cell is limiting the overall current can lead to a large increase in efficiency, even with realistic experimental losses and nonunity reflection of the spectral splitter.

Planar perovskite solar cell (PSC) measuring 900 nm total thickness is designed and simulated using Silvaco and SCAPS. Silvaco (Atlas 5.16.3.R) photovoltaic simulating system enables the formation of the stacking model and estimation of the physical properties of various functional materials, whereas SCAPS (version. 3.3.07) patterns the photovoltaic metrics including the fill factor (FF), power conversion efficiency (PCE), open-circuit voltage (Voc), short-circuit current density (Jsc), maximum voltage (Vm), maximum current (Im), absorption and reflection coefficients, and energy state diagram of the whole device. Alternation of illumination power and use of different buffer materials was utilized as the main tuning strategy. The champion layout was achieved by optimization of the stacking model, material system, and power of illumination, which demonstrated 26.32% PCE, 83.77% FF, Jsc of 26.27  mA  /  cm², and the exceptional Voc of 1.19 V. This theoretical performance remains stable in 1000  W  /  m² light radiation. The calculated efficiency and FF were very close to the previously reported experimental data, and this proved the high accuracy of this simulation work. These findings promise a feasible application of PSC in high-efficiency wearable electronics.

Corncob is an extremely cheap and easily available biomass with excellent hydrophilicity. Crisscross pores of corncob provide channels for efficient water transport. An efficient solar evaporator is prepared by coating carbon black (CB) film on corncob. The light absorption of corncob coated with CB film is significantly enhanced, and the absorptance is more than 94% in solar waveband. The evaporation rate of CB-coated corncob is 1.425  kg/m²h, 78.1% higher than that of uncoated corncob. The height of corncob above water has an important influence on evaporation performance. The maximum evaporation rate is 1.88  kg/m²h when the corncob is 2 cm above water. Compared with 0 cm above water, the evaporation rate of corncob with 1, 2, and 3 cm above water increases by 13.7%, 32%, and 24%, respectively. The effect of light intensity on evaporation performance is studied. Although increasing the light intensity can achieve a higher evaporation rate, it will increase the complexity and cost of the solar evaporation device. With the advantages of rich raw materials and low cost, the corncob-based interfacial evaporator can reuse the crop waste. More importantly, the preparation method is very simple, and the whole process does not need to use complex mechanical equipment. This study will boost the applications of biomass materials in the field of solar vapor generation.