Newly designed donor–acceptor SAMs enable efficient and stable perovskite solar cells through improved buried-interface control.
Researchers have been working to improve perovskite solar cells not only by optimizing the light-absorbing layer itself, but also by refining the interface materials that play a key role in charge extraction and device stability.
In inverted perovskite solar cells, self-assembled materials (SAMs), are widely used as hole-selective layers. Among them, Me-4PACz has become one of the most common choices, but it still suffers from several drawbacks, including molecular aggregation, limited wettability toward the perovskite precursor, and insufficient contact at the buried interface. These issues can disrupt perovskite film formation inside the device.
In this study, published in Small, researchers developed a new molecular design strategy to address these limitations by introducing two newly designed donor–acceptor SAMs, LYS-H and LYS-F. These materials were created to improve the quality of the buried interface, where the perovskite layer meets the underlying charge-transporting surface.
The team found that the new SAMs could first reduce the aggregation problems associated with conventional Me-4PACz, leading to a more uniform interfacial layer and improved perovskite precursor spreading on the substrate.
With a better-controlled buried interface, the perovskite layer was then able to grow with improved crystallinity and fewer buried defects. This helped support more efficient charge transport and better overall device performance. Among the two molecules, the fluorinated version, LYS-F, delivered the strongest results. Solar cells using LYS-F achieved a power conversion efficiency of 25.02% and a fill factor of 83.64%, demonstrating clear gains in both efficiency and device quality.
Beyond performance, the new SAMs design also improved the stability of unencapsulated devices stored under ambient conditions. This is especially important for the future development of perovskite photovoltaics, because commercial solar technologies must combine high efficiency with long-term durability.
By showing that molecular interface engineering can reduce SAMs aggregation, improve film growth, and enhance both efficiency and stability, this work provides a promising route toward more practical and commercially viable perovskite solar cells.
“This work shows how molecular design can overcome buried-interface limitations and unlock more efficient, stable perovskite solar cells,” said co-corresponding author Chu-Chen Chueh, Ph.D., professor of chemical engineering at National Taiwan University.
Prof. Chu-Chen Chueh's email address: [email protected]
