Solar windows from carbon nanoparticles

Windows that generate energy from sun radiation are amongst the emerging technologies in the construction industry. They are called luminescent solar concentrators (LSC) and they consist of colored and semi-transparent glass panes, whose surface is enriched with pigments that capture sunlight and send it back towards solar panels distributed along the borders. The research world is studying a way to make these devices as efficient and ecological as possible. 

An Italian-Chinese test coordinated by Alberto Vomiero, professor at Ca’ Foscari University of Venice and the Luleå Tekniska Universitet in Sweden, has taken a step forward in this direction, obtaining an efficiency record using carbon nanoparticles as pigments, known as carbon dots, and developing a method to mass produce these particles, a million times smaller than a millimeter. 

The study has been published as the cover story of Energy and Environmental Science, one of the most important scientific journals in the fields of materials for energy applications. 

“The research has shown that it is possible to produce eco sustainable LSCs - explains Alberto Vomiero - starting from carbon quantum dots obtained from citric acid and urea, through a vacuum-seal process. The radiation that gets converted into energy is not the same that hits the window, but rather the one generated by the carbon dots, which absorb part of the solar radiation and emit light back. This light then is ‘guided’ from the glass pane toward the borders, where the solar panels are located.”   

The efficiency and the production method of the carbon dots illustrated by the study make these luminescent nanoparticles of great interest for the field’s industry. 

LSC windows have been around for decades, but they have never reached the necessary characteristics to become desirable to a larger market. 

Scientific results such as these can accelerate the innovation and the application as a semi-transparent coating for buildings, that would thus generate renewable energy. 

The study was a collaborative effort of scientists from Ca’ Foscari, Qingdao University, Luleå University of Technology, Wuhan University of Technology, Politecnico di Milano.

The article

Gram-scale synthesis of carbon quantum dots with a large Stokes shift for the fabrication of eco-friendly and high-efficiency luminescent solar concentrators

Energy and Environmental Science

Link to the research: doi.org/10.1039/D0EE02235G