The current crop of window materials incorporating photovoltaic cells perform efficiently in terms of power production but often at the expense of limited window transparency. In pursuit of the best of both worlds, an international research team designed a window with a wavelength-selective film, consisting of cesium tungsten oxide and resin.

This material is characterized by high visible-light transmittance of up to 88% and also allows for efficient and selective harvesting of ultraviolet and infrared light for conversion to heat energy. Thermoelectric devices arranged along the film edges then convert that heat into electricity. A prototype system was demonstrated Working principle of transparent power generation windows based on wavelength-selective solar-thermoelectric conversion. Source: Lidong Chen et al.to produce an output voltage of 4 V within an area of 0.01 m² exposed to sunshine.

The design of the power generating system detailed in Advanced Energy Materials decouples energy conversion efficiency from light transparency of the window, enabling independent regulation for both. This technology can also reduce the cooling load of buildings as a result of infrared light absorption.

Researchers from the Chinese Academy of Sciences, Donghua University (China), Leibniz Institute for Solid State and Materials Research (Germany) and Coventry University (U.K.) contributed to this development.