Researchers restore the performance of quantum dot solar cells as if 'flattening crumpled paper'

Perovskite quantum dots are critical materials for next-generation solar cells. They have excellent light-to-electricity conversion capabilities and are easy to mass-produce. However, to utilize them in solar cells, the "ligands" attached to the quantum dot surface must be replaced. This process often leads to distortions of the quantum dot surface, resembling crumpled paper, which results in decreased performance and shorter lifespans for the solar cells.

To address this issue, Professor Jongmin Choi's team newly adopted short ligands that securely hold the quantum dots from both sides, effectively uncrumpling the distorted surface. The ligands help restore the distorted lattice structure, smoothing the crumpled surface of the quantum dots. This significantly reduces surface defects, enabling the solar cells to operate more efficiently and extending their lifespan. Consequently, the power conversion efficiency of the solar cells increased from 13.6% to 15.3%, demonstrating stability by maintaining 83% of their performance for 15 days.

"Through this research, we could minimize surface defects on the quantum dots and stabilize their surfaces by newly adopting these amphiphilic ligands, thereby significantly improving the efficiency and stability of the solar cells," said Professor Jongmin Choi from the Department of Energy Science and Engineering at DGIST. "We plan to continue our research on stabilizing the surface of perovskite quantum dots, hopefully applying the results to various photoelectric devices."

This study was a joint effort by the research teams of DGIST Professor Jongmin Choi, Gyeongsang National University Professor Tae Kyung Lee, and Kookmin University Professor Younghoon Kim, led by Gayoung Seo and Sanghun Han from DGIST, along with Donggyu Lee, a Ph.D. candidate from Gyeongsang National University. The study was supported by the National Research Council of Science & Technology's Creative Convergence Research Project, the DGIST R&D Program, and the New Faculty Research Foundation Project at Gyeongsang National University. The research findings were published in the international journal Chemical Engineering Journal on September 15, 2024.