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New Molecular Design Strategy Improves Intrinsic Stability, Overcoming Previous Limitations
A joint research team from Korea and China has achieved a world-class certified power conversion efficiency (PCE) of 27.6% for a next-generation single-junction perovskite solar cell. This achievement is notable for its strategy of improving efficiency at the molecular design level, a departure from previous research that primarily focused on enhancing structural stability and efficiency through external modifications to the solar cell.
A team led by Professor Park Nam-gyu of Sungkyunkwan University’s School of Chemical Engineering, in collaboration with researchers from China’s Huazhong University of Science and Technology, Harbin Institute of Technology, and Shenzhen Polytechnic, successfully boosted the efficiency of perovskite solar cells to a world-leading level, publishing their findings in the international academic journal ‘Science’ on the 14th (local time).
Commercial single-junction silicon solar cells have a theoretical efficiency limit of 29%. Perovskite is particularly noteworthy in the display and solar cell fields due to its high light absorption rate and energy conversion efficiency, coupled with relatively low manufacturing costs. In theory, a multi-junction configuration stacking silicon and perovskite layers could achieve a solar cell efficiency of up to 80%.
Having recently surpassed the 27% efficiency barrier and closing the gap with silicon solar cells, the primary challenge for perovskite solar cells is ensuring stability. Perovskite crystals are vulnerable to high temperatures and humidity, which can easily cause their internal crystal structure to collapse during repeated operation.
The research team improved the crystal’s intrinsic stability by adding an additive called ‘3-PMPCl’ to both the interior and surface of the crystal. Experiments confirmed their success, achieving a world-leading power conversion efficiency of 27.6%. However, the electrode materials used to achieve this top efficiency, silver (Ag) and gold (Au), are somewhat susceptible to long-term instability due to chemical bonding and ion penetration.
The team applied a bismuth (Bi) electrode as an alternative material. While this resulted in a slight decrease in efficiency to about 26.8%, it secured high stability, retaining over 93% of the initial efficiency for 1011 hours under solar-level light irradiation and high-temperature conditions.
The core of this research is its paradigm shift away from external reinforcement and toward an intrinsic stabilization strategy through molecular design. The proposed approach is expected to be applicable not only to perovskites but also to other flexible semiconductor materials.
“These are still results based on small-area devices, and further verification is needed for large-area uniformity, module manufacturing feasibility, and scalability,” Professor Park explained. Supported by the Leader Research Program of the Ministry of Science and ICT and the National Research Foundation of Korea, Professor Park, along with postdoctoral researcher Dr. Sanyuan Niu from his lab, was extensively involved in the project, from research planning and conducting key optoelectronic characterization experiments to writing the paper.
Professor Park also noted that next-generation solar cell research in China is advancing very rapidly and is already in the stages of preparing for mass production. “China has recently expanded its research scope beyond simple efficiency competition to operational stability, green solvent processes, and machine learning-based material design,” he said. “It is understood that more than 100 companies are moving past the R&D stage and preparing for mass production.”
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– doi.org/10.1126/science.aeb9953
