Transparent Power‐Generating Windows Based on Solar‐Thermal‐Electric Conversion

Abstract

Integrating transparent solar‐harvesting systems into windows can provide renewable on‐site energy supply without altering building aesthetics or imposing further design constraints. Transparent photovoltaics have shown great potential, but the increased transparency comes at the expense of reduced power‐conversion efficiency. Here, a new technology that overcomes this limitation by combining solar‐thermal‐electric conversion with a material's wavelength‐selective absorption is presented. A wavelength‐selective film consisting of Cs0.33WO3 and resin facilitates high visible‐light transmittance (up to 88%) and outstanding ultraviolet and infrared absorbance, thereby converting absorbed light into heat without sacrificing transparency. A prototype that couples the film with thermoelectric power generation produces an extraordinary output voltage of ≈4 V within an area of 0.01 m2 exposed to sunshine. Further optimization design and experimental verification demonstrate high conversion efficiency comparable to state‐of‐the‐art transparent photovoltaics, enriching the library of on‐site energy‐saving and transparent power generation.

Selective Solar Harvesting Windows for Full‐Spectrum Utilization

“…Concurrently, the TSA is utilized as the interior window (Figure 1d ), which transmits visible light and absorbs the remaining UV and NIR to produce heat, owing to the localized surface plasmon resonances of CWO nanoparticles (NPs). [ 14a ] Subsequently, thermal energy is mostly extracted by the ventilated air within the gap for various purposes such as indoor space heating in cold seasons.…”

“…The cross‐sectional scanning electron microscope (SEM) image (Figure S3 , Supporting Information) shows the selective photothermal coating on the substrate. The impacts of mass fraction of CWO NPs and absorber thickness on the photothermal efficiency have been extensively quantified, [ 14a ] and thereby, here, we adopted the optimal design. Figure 2c shows the spectra of the CWO coated glass, exhibiting an exceptional spectral selectivity, i.e., absorption of the UV and NIR and transmission of the visible light.…”

“…Until recently, a few highly efficient and cost‐effective TSAs have been reported. [ 14 ] We developed a cesium‐doped tungsten trioxide (CWO) based TSA that achieved a visible transmittance of up to 82% and an absorption of NIR of >90%, [ 14a ] offering a great opportunity for transparent solar–thermal conversion. Later, a power‐generating window was developed by coupling the CWO‐based TSA with thermoelectric devices and demonstrated a conversion efficiency comparable to state‐of‐the‐art TPVs.…”

“…Later, a power‐generating window was developed by coupling the CWO‐based TSA with thermoelectric devices and demonstrated a conversion efficiency comparable to state‐of‐the‐art TPVs. [ 14b ] However, such a power‐generating window suffered from low thermal‐to‐electricity conversion efficiency as well as incompactness and aesthetic problems, as bulk thermoelectric devices were incorporated in the system. Up to date, despite these efforts, full‐spectrum solar utilization, i.e., selectively transmitting visible light and harvesting both UV and NIR light, is still unavailable for window applications.…”

Li+/Al3+ Composite Solid Electrolyte Based Electro‐Thermal Dual Responsive Devices with Optimized Optical Contrast and Cycle Durability

“…Chromogenic-type smart windows with controllable visible and near-infrared light transmittance can significantly improve a building's energy efficiency and residential comfort. [1,2] According to the responsive modes, chromogenic materials which change stable and reversible optical states under external field stimulation (electric field, temperature, illumination, and atmosphere) can be divided into electrochromic, [3,4] thermochromic, [5,6] photochromic, [7,8] and gasochromic [9,10] types, etc. Among them, WO 3 -based electrochromic devices (ECDs) and VO 2 -based thermochromic devices (TCDs) have become the representative of active and passive smart windows respectively, which are also promising to market application.…”