KU Research Team Enables Power Generation Regardless of Time or Weather with Transparent Solar Window Technology
- categorization Research
- writing date 2025.12.30
- author Communication Team
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KU Research Team Enables Power Generation Regardless of Time or Weather with Transparent Solar Window Technology
△ Structure of the distributed Bragg reflector (DBR)-silicon hybrid solar window.
A research team led by Professor Jun Yong-seok from the Department of Integrative Energy Engineering and the Graduate School of Energy and Environment (Green School) at KU (President Kim Dong-One), in collaboration with research teams from Korea Aerospace University and the Korea Institute of Science and Technology (KIST), has developed a transparent solar window technology that can generate power 24 hours a day using sunlight during the day and indoor lighting at night.
The research results were published online on November 21 and published in print on December 17 in Joule (IF=35.4), a world-renowned international academic journal in the energy field.
*Article title: Scalable hybrid solar window with high transparency, high efficiency, and superior color rendering
*DOI: 10.1016/j.joule.2025.102216
*URL: https://doi.org/10.1016/j.joule.2025.102216
Existing transparent solar cells face a contradiction: increasing transparency leads to a decrease in power generation efficiency, while increasing efficiency reduces transparency. Moreover, thin-film solar cells distort the color of light during the absorption process, creating limitations for their application as building-integrated photovoltaics (BIPV).
* Building-integrated photovoltaics (BIPV): A futuristic energy system in which solar power modules are directly integrated into building structures such as rooftops, facades, and windows, simultaneously performing the functions of construction materials and power generation devices.
To overcome these limitations, the research team designed a new structure combining a distributed Bragg reflector (DBR) with bifacial silicon solar cells. This structure allows visible light to pass through while selectively reflecting invisible near-infrared light toward the solar cells. In this manner, the technology can maintain bright transparency like a window while simultaneously increasing power generation efficiency.
*Distributed Bragg reflector (DBR): An optical film that reflects light of specific wavelengths while transmitting the rest.
*Bifacial silicon solar cell: A solar cell that generates electricity by utilizing light entering from both the front and back surfaces.
By utilizing the characteristics of bifacial solar cells, the team implemented a 24-hour power generation system that generates power by absorbing sunlight during the day and indoor light from sources like LEDs and fluorescent lamps at night. This ensures a stable power supply regardless of changes in time or weather, which distinguishes it from existing technologies.
The solar window module developed by the research team recorded high power generation efficiency while achieving a visible transmittance of 75.6%, providing brightness similar to an actual window. Furthermore, the color rendering index, which indicates how accurately the colors of light passing through the window are reproduced, reached 93.8%, effectively solving the color distortion issue that had plagued previous transparent solar cells.
Professor Jun said, “Our results demonstrated that we can utilize invisible infrared rays and indoor lighting as energy while maintaining window transparency. In the future, our technology can be applied to various industrial sectors, such as zero-energy buildings and windows for electric vehicles.”
This study was supported by the Ministry of Trade, Industry and Resources and the Korea Institute of Energy Technology Evaluation and Planning (KETEP).
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