Researchers at the School of Energy and Chemical Engineering at UNIST have achieved a significant milestone in solar energy by creating the world’s most efficient quantum dot (QD) solar cell. The team utilized an innovative ligand exchange technique to synthesize organic cation-based perovskite quantum dots (PQDs). This approach addresses the challenges associated with defects in the crystals and surfaces of organic PQDs, pushing the efficiency of QD solar cells to an impressive 18.1%.
The study, published in Nature Energy, marks a notable achievement as the developed technology boasts the highest efficiency among quantum dot solar cells recognized by the National Renewable Energy Laboratory (NREL) in the United States. The research enhances the efficiency of organic PQDs and ensures exceptional stability, with the solar cells maintaining their performance even after two years of long-term storage.
The research team employed an alkyl ammonium iodide-based ligand exchange strategy, creating a photoactive layer of QDs with high substitution efficiency and controlled defects. This research opens new possibilities for the future of QD solar cell material research.
Simultaneously, the Korea Institute of Energy Research (KIER) has made remarkable strides in the stability and efficiency of semi-transparent perovskite solar cells.
To overcome challenges in the fabrication process, the research team at KIER utilized electro-optical analysis and atomic-level computational science. They discovered that lithium ions added to enhance the electrical conductivity of the hole transport layer caused degradation in the metal oxide buffer layer’s characteristics. By optimizing the oxidation time of the hole transport layer, the researchers successfully mitigated the diffusion of lithium ions, resulting in improved stability.
The developed semi-transparent perovskite solar cells exhibited an impressive efficiency of 21.68%, surpassing all transparent electrode perovskite solar cells. Moreover, they retained over 99% of their initial efficiency for 400 hours in dark storage and more than 240 hours in continuous operation, showcasing exceptional stability and efficiency.
The research team further applied the developed solar cells as the top cell of tandem solar cells, creating the country’s first bifacial tandem solar cells. In collaboration with Jusung Engineering Co., Ltd., and the German Jülich Research Center, the bifacial tandem solar cells achieved high bifacial equivalent efficiencies of 31.5% for four-terminal and 26.4% for two-terminal configurations under conditions where the reflected light from the rear was 20% of standard sunlight.
The research’s implementable solution holds excellent potential for future advancements in solar cell technologies.
These groundbreaking achievements in quantum dot and semi-transparent perovskite solar cells represent significant strides toward commercializing next-generation solar cells. As the world moves towards carbon neutrality by 2050, these advancements, and others, are crucial in achieving ultra-high efficiency and diversifying application areas for solar cell technology, overcoming constraints in installation spaces and national land area.
