Breakthrough glass generates energy: Car windows, mobile screens to charge batteries

Researchers have developed a new method that can directly charge a battery from a smartphone screen. Developed by a research team affiliated with UNIST, the method can directly supply energy from glass of buildings, cars, and mobile devices through transparent solar cells.

The new type of transparent solar cell and module offers high efficiency and maintains glass-like colorless and transparent properties.

The transparent solar cell secured colorless and transparentness by introducing an ‘all-back-contact’ design that places all the components of the solar cell on the back. It has achieved high efficiency and aesthetics that transparent solar cells must have at the same time.

Transparent cell module has high efficiency

The material is developed by Professor Kwanyong Seo and his research team at the School of Energy and Chemical Engineering at UNIST.

Called Seamless Modularization technology , the method eliminates gaps between devices without using metal wires. In the existing modularization method, the gap between devices and opaque metal wires have solved the problem of damaging the aesthetics of transparent solar cells.

The newly developed 16 cm²-sized transparent solar cell module has high efficiency ranging from 20% to 14.7% in transmittance while maintaining aesthetics similar to that of a single device. It has also succeeded in charging a smartphone using natural sunlight. It also proved the possibility that a screen of a small mobile device can be used as an energy source, according to the study conducted at UNIST .

Transparent solar cells can be used in buildings, automobile glass

“This study fundamentally solved the aesthetic problem of the existing solar cell modularization method through the design of the new device structure,” said researcher Jeonghwan Park and Research Assistant Professor Kangmin Lee.

“It presented the possibility that transparent silicon solar cells can be used in various industries such as small devices as well as buildings and automobile glass.

Seo maintained that the study has opened a new path for modularization research, which is essential for commercialization of transparent silicon solar cells.

“We plan to continue further research so that transparent solar cells can become a key technology in the eco-friendly future energy industry,” added Seo.

Published in the international journal Proceedings of the National Academy of Sciences (PNAS), the all-back-contact (ABC) design design not only demonstrates high power conversion efficiency (PCE) in solar cells but also ensures unobstructed visibility through transparent solar modules. Notably, ABC-transparent c-Si solar cells achieved a peak PCE of 15.8% while maintaining an average visible transmittance of 20%.

Through seamlessly interconnecting the unit cells, the output voltage and power were systematically tuned from 0.64 V and 15.8 mW (for a 1 cm2-sized unit cell) to 10.0 V and 235 mW (for a 16 cm2-sized module). Furthermore, we successfully demonstrated the photocharging of a smartphone using a transparent ABC solar module, according to the study .