Researchers in Korea have developed a translucent organic solar cell with an efficiency exceeding 10%.
Yang Chang-deok, a professor in the Department of Energy and Chemical Engineering at the Ulsan National Institute of Science and Technology (UNIST), noted that the research team developed a translucent organic solar cell with a power conversion efficiency of 10.81% and a visible light transmittance of 45.43% on the 15th. The research results were published on June 7 in the international journal "Angewandte Chemie International Edition."
The reason solar cells on roofs or roads appear black is that the cells absorb sunlight to generate electricity. The more sunlight is absorbed, the higher the efficiency of the cells. Conversely, for an object to appear transparent, sunlight must not be absorbed but rather pass through. This is why developing high-efficiency transparent solar cells is challenging.
The secret behind the newly developed translucent solar cell lies in the high-performance photoactive layer that selectively absorbs only infrared light. This photoactive layer allows nearly half of the visible light spectrum to pass through while absorbing the invisible infrared spectrum to generate electricity.
When generating power by absorbing infrared light, the power conversion efficiency is naturally lower than when absorbing high-energy visible light; however, the research team solved this issue by newly designing the receptor molecular structure of the photoactive layer.
The photoactive layer of organic solar cells consists of a "donor" that gives electrons and a "receptor" that receives electrons. The "4FY" receptor molecule synthesized by the research team is symmetrically structured as receptor-donor-receptor overall, but it is designed to induce local asymmetric interactions between fluorine and hydrogen, as well as fluorine and sulfur. This molecular structure improves the alignment between molecules and secures charge transport pathways, thereby increasing cell efficiency.
Yang Sang-jin, the first author of the study, explained, "Asymmetry increases cell efficiency but has the problems of shorter lifespan and difficulty in synthesis. However, by inducing local asymmetry within the molecular structure, we have created a structure that leverages the advantages of both symmetry and asymmetry."
This solar cell was subjected to a total of 134 hours of "dial cycle (diurnal) stability testing" simulating outdoor conditions that alternate between day and night, proving to maintain most of its initial performance and demonstrating high durability. This represents about a 17-fold increase in lifespan compared to existing receptor molecular-based translucent solar cells.
Professor Yang Chang-deok said, "It presents a new way of generating electricity with invisible light and will help in developing 'invisible power plants' in various environments such as smartphone protective films, building windows, and transparent displays."
References
Angewandte Chemie International Edition (2025), DOI: https://doi.org/10.1002/anie.202424287