London scientists are ushering in a new era in solar energy: windows are being turned into generators

In a world where the search for more sustainable energy sources is high on the agenda, a research team from University College London (UCL) has taken a significant step forward by developing innovative semi-transparent solar cells. This revolutionary technology has the potential to transform ordinary windows in buildings, cars, and even clothing into efficient electricity generators, taking the concept of “smart” homes to a new level.

Windows that glow and generate energy

Traditionally, solar panels are placed on roofs, while vast window areas in modern architecture remain untapped as a source of solar power. University College London has addressed this oversight by offering a solution that combines the aesthetic appeal of transparent surfaces with the functionality of solar cells. The new cells allow around 30% of sunlight to pass through, significantly less than the 80-90% in standard windows; however, this portion of light is optimized for maximum electricity generation efficiency.

“We have demonstrated that it is possible to preserve a window’s transparency so that it lets light through while still providing solar-cell efficiency,” says Mojtaba Abdia-Jalebi, lead author of the study from UCL’s Institute for Materials Discovery. This opens the door to integrating solar technologies into everyday life in ways that once seemed like science fiction.

Expanding horizons: flexibility and multifunctionality

The next stage of development, as Abdia-Jalebi emphasizes, is to create flexible solar cells. This will make it possible to use them not only on flat glass surfaces, but also on curved ones, for example on the windows of iconic buildings such as London’s Shard skyscraper, or even on car windshields. In addition, flexibility opens the way for using these cells on non-rigid surfaces such as clothing or backpacks, which could become a real breakthrough for portable energy solutions.

“We would also like to create solar cells on a larger scale than those we achieved in this study,” adds Abdia-Jalebi, pointing to the team’s ambitious plans for the future implementation of the technology.

Natural tinting and energy efficiency

Beyond generating electricity, the new technology has another major advantage: it can also act as natural window tinting. Siming Huang, another lead author of the study, notes that this could significantly save electricity used to cool indoor spaces, especially in hot regions. This makes the development particularly relevant for climates where air conditioning systems consume a significant share of buildings’ total energy use.

The magic of perovskite: a new direction in photovoltaics

A key component of the development is the use of perovskite, a material that differs from traditional silicon-based photovoltaic cells. Perovskite has a unique ability to generate electricity even from indoor lighting, because its chemical composition can be easily modified to optimize the absorption of different wavelengths of light. This property makes it ideal for applications where direct sunlight may be limited.

The researchers used computer modeling to achieve the ideal balance between transparency and efficiency. They were able to create a perovskite layer only 185 nanometers thick, which is significantly thinner than in traditional silicon cells (where the perovskite layer is usually 3-4 times thicker).

Improving stability and transparency

To overcome the challenges associated with the stability of perovskite solar cells, the team added a special molecule to the composition: 3-trifluoromethyl-1H-1,2,4-triazole. This component plays a crucial role in reducing defects in the perovskite crystal structure, known as “traps.” These “traps” can hinder electron movement, reducing the efficiency of converting light into electricity. Adding this molecule helps stabilize the structure, preventing the material from degrading over time.

Another innovative solution was the creation of a transparent electrode. In traditional perovskite cells, the electrode is made of gold, which blocks sunlight. The scientists overcame this limitation by placing a thin layer of gold between two transparent layers of molybdenum oxide. This configuration allows light to pass through the gold layer, significantly reducing light losses due to reflection.

Impressive results and prospects

The experimental results are impressive. A 30 × 30 cm panel demonstrated the ability to convert 22% of bright indoor light (1000 lx) into electricity and 14% of sunlight. An important indicator is the durability of the development: even without additional protective elements, the device retained 80% of its efficiency over 300 hours of continuous light exposure under standard accelerated durability tests.

The study, published in the respected journal Advanced Energy Materials, opens up new prospects for solar energy. The ability to integrate energy generation directly into the architecture of buildings, vehicles, and even everyday objects could significantly reduce dependence on traditional energy sources and help build a more environmentally friendly future. The potential of this technology is enormous, and with further development it may become one of the key elements of the global transition to renewable energy.