A major research breakthrough in solar energy has led to the development of the world’s most efficient quantum dot (QD) solar cell, making a significant leap toward the commercialization of next-generation solar cells. This state-of-the-art QD solution and device has demonstrated exceptional performance, maintaining its performance even after long-term storage. Led by Professor Sung-Yoon Jung of UNIST’s School of Energy and Chemical Engineering, a team of researchers has unveiled a new ligand exchange technique. This innovative approach enables the synthesis of organic cation-based perovskite quantum dots (PQDs), ensuring exceptional stability while suppressing intrinsic defects in the photoactive layer of solar cells.

“Our developed technology has achieved an impressive efficiency of 18.1% in QD solar cells,” Professor Jung said. “This remarkable achievement represents the highest performance in quantum dot solar cells recognized by the National Renewable Energy Laboratory (NREL) in the United States.”

The growing interest in related fields is evident, as last year, three scientists who discovered and developed QDs as products of advanced nanotechnology were awarded the Nobel Prize in Chemistry. QDs are semiconducting nanocrystals with typical dimensions ranging from several to tens of nanometers, capable of controlling photoelectric properties based on their particle size. PQDs, in particular, have received significant attention from researchers due to their outstanding photoelectric properties. Additionally, their manufacturing process involves simple spraying or solvent application, eliminating the need for growth processes on substrates. This streamlined process allows for high-quality production in a variety of manufacturing environments.

However, the practical use of QDs as solar cells requires a technology that reduces the distance between QDs by ligand exchange, a process that allows a large molecule, such as a ligand receptor, to bind to the QD. Connects to the surface. Organic PQDs face significant challenges, including defects in their crystals and surfaces during the substitution process. As a result, inorganic PQDs with efficiencies limited to 16% have been mainly used as materials for solar cells.

In this study, the research team used an alkyl ammonium iodide-based ligand exchange strategy, effectively substituting ligands for organic PQDs with optimal solar applications. This breakthrough enables the fabrication of photoactive layers of QDs for solar cells with high switching efficiency and controlled defects.

As a result, the efficiency of organic PQDs, previously limited to 13% using existing ligand substitution technology, has been significantly improved to 18.1%. Moreover, these solar cells exhibit exceptional stability, maintaining their performance even after long-term storage for more than two years. The newly developed organic PQD solar cells exhibit both high efficiency and stability simultaneously.

“Previous research on QD solar cells mainly used inorganic PQDs,” noted Sang Hok Lee, first author of the study. “Through this study, we have demonstrated the potential by addressing the challenges associated with organic PQDs, which have proven difficult to use.”

Prof. Jung commented, “This study presents a new direction for ligand exchange mechanisms in organic PQDs, which serves as a catalyst to revolutionize the field of QD solar cell materials research in the future. “

The results of the study, co-authored by Dr. Javed Akuma Khairuddin and Sang Hock Lee, have been published online. Energy of nature On 27 January 2024. This research was made possible with the support of the Basic Research Laboratory (BRL) and the Mid-Career Researcher Program, as well as the Nano·Material Technology Development Program, funded by the National Research Foundation of Korea (NRF) under the Ministry of Science and Technology. Under ICT (MSIT). It is also supported by ‘Global Basic Research Lab Project’.