Scientists from the Polytechnic University of Catalonia, the University of Barcelona and the Catalonia Institute for Energy Research have created prototypes of transparent solar cells based on an amorphous silicon-carbon alloy. These devices transmit over 60% of visible light while remaining fully functional electricity generators. In these solar panels, glass essentially becomes an invisible battery that can be integrated into windows, building facades, cars, or even used indoors to power sensors and IoT devices.
The biggest obstacle to the development of transparent solar panels in recent years has been the inconsistency of traditional amorphous silicon: it is generally reliable and stable, but it absorbs too much light. As a result, silicon-based panels tend to be dark or have low power output. Reducing the layer thickness increases transparency but also affects energy efficiency.
To overcome this limitation, the researchers started adding carbon atoms to the amorphous silicon structure. By varying the gas ratio during deposition, they learned to control the material’s band gap and thus regulate its transparency. The higher the carbon content, the higher the light transmittance. During experiments, they achieved not only a stable 60% light transmittance, but also almost 90% transmittance in some samples.
Needless to say, the transparency increase was accompanied by a decrease in the generated current. Nevertheless, they found a reasonable compromise. Laboratory samples demonstrated a light utilization efficiency of approximately 1.3%, which is sufficient for applications where high power is not as important as aesthetics and environmental integration.
The new solar cells had a particular advantage in low-light conditions. In contrast to other technologies, they maintained stability under lamps or in diffuse daylight, making them suitable for indoor use. In this respect, they outperformed their organic and perovskite counterparts: while organic materials quickly degrade under UV light and perovskites suffer from instability and toxicity, amorphous silicon has proven itself to be a durable and easily reproducible material.
The researchers stress that continuous optimization of layer thicknesses and anti-reflective coatings could further improve panel performance. This opens up prospects for the mass production of transparent and reliable solar panels that will no longer be hidden on roofs but can be seamlessly integrated into windows or used indoors, transforming familiar surfaces into new sources of clean energy.
