- Accelerate commercialization by controlling quantum dot crystal arrays and enhancing charge transport with conjugated polymer ligands 

  A research team led by Professor Min Kim of the Department of Chemical Engineering at the University of Seoul (Lead authors: Tae Oh Yoon, Shabaz Alam, and Dohun Baek), in collaboration with Professor Jaeyoung Jang of Hanyang University and Professor Jaewon Lee’s research team at Chungnam National University. The collaborative research paper, titled “Conjugated Polymer-Driven Compact Crystal Packing and Efficient Charge Transport in Perovskite Quantum Dot Solar Cells,” was published as a frontispiece in Small, leading international journal in nanoscience and materials science (Impact Factor 12.1, top 8.7% in JCR).

The joint research team designed a novel conjugated polymer ligand with an ethylene glycol side chain, implementing a strategy that enables precise control of quantum dot crystal arrays through polymer backbone bonding while strongly interacting with the perovskite quantum dot (PQD) surface. This demonstrates that the conjugated polymer effectively stabilizes defects on the quantum dot surface while simultaneously enhancing the dense arrangement and electron coupling between quantum dots, thereby significantly improving charge transport pathways.

  Unlike conventional insulating ligands, the conjugated polymer developed by the research team simultaneously performs two core functions: surface passivation and crystal array control. In particular, conjugated polymers exhibit excellent packing density due to the planar structure of their alkoxy side chains, and charge transport was maximized through control of molecular orientation in the vertical direction.

  In terms of solar cell performance, the research team confirmed that the power conversion efficiency (PCE) of PQD solar cells with this conjugated polymer ligand improved by more than 10% compared to existing efficiencies. What is even more noteworthy is that it maintained more than 85% of its initial efficiency after 850 hours of continuous operation, demonstrating excellent long-term stability.

  Professor Min Kim stated, “The findings of this research demonstrate that the crystal arrays and charge transport of quantum dots can be precisely controlled using only conjugated polymers,” adding, “This study demonstrates that the findings can contribute to creating a key strategy to accelerate the practical application of high-efficiency, high-stability perovskite quantum dot solar cells.”

  This collaborative research, conducted by the University of Seoul, Hanyang University, and Chungnam National University, is of considerable significance. It not only demonstrated the potential for mass production and commercialization of quantum dot solar cells for next-generation optoelectronic devices but also opened a potential area for new research: controlling nanocrystal assembly through polymer-based surface engineering.

  This research was supported by the Ministry of Science and ICT and the National Research Foundation of Korea (NRF) through the Young Researcher Program.

▶ Tae Oh Yoon (Master’s student), Professor Jaeyoung Jang (Hanyang University), Professor Jaewon Lee (Chungnam National University), and Professor Min Kim (University of Seoul)