A combination photovoltaic window device that generates electric power from sunlight and simultaneously blocks the heat-producing portion of the solar spectrum may drastically cut homeowners’ energy bills, according to a study (Joule 2018, DOI: 10.1016/j.joule.2018.06.006).
Organic photovoltaic (OPV) devices can be thin, lightweight, and transparent, making them well suited for converting ordinary windows to power-producing panels. Another window innovation is heat-control window films that reduce unwanted solar heating on sunny days and minimize heat loss on cool days.
Incorporating heat control into OPV window devices sounds like a winning proposition to conserve energy. But making such a multifunctional device that is also transparent remains challenging because of performance trade-offs associated with the materials and design choices that improve power production, heat control, and light transmission. An improvement in one area typically comes at the expense of another.
Now, Hin-Lap Yip and Fei Huang of South China University of Technology and coworkers have negotiated that complex balancing act. The team made a multilayered semitransparent device that achieves a 6.5% power production efficiency (record-setting OPVs hit about 11.5%); rejects more than 80% of heat-causing infrared light, which is comparable to commercial window films; and transmits 25% of visible light. The device uniquely includes an organic material that efficiently harvests near-IR light, which helps boost power generation and cut heat transmission. The team suggests that improvements may eventually cut an average household’s external power demand by up to 50%.