Researchers have leveraged electron spin resonance technology to examine the state and movement of electrical charges in Ruddlesden-Popper tin-based perovskite solar cells. This innovative technology is paving the way for the next generation of solar cells. The team has identified a mechanism that enhances the performance of these cells when compared to traditional three-dimensional tin-based perovskite solar cells. This breakthrough indicates significant progress towards creating solar cells that are both highly efficient and durable.
Experts from the University of Tsukuba have employed electron spin resonance technology to study the state and dynamics of charge in Ruddlesden-Popper tin-based perovskite solar cells, a promising technology for future solar energy solutions. They have uncovered a mechanism that boosts the performance of these cells beyond that of standard three-dimensional tin-based perovskite solar cells. This discovery marks a significant advancement in the quest for high-efficiency, long-lasting solar energy solutions.
Perovskite solar cells are gaining attention as the next wave of solar technology, due to their high efficiency, flexibility, and printability, among other benefits. However, early versions used lead, raising concerns about toxicity and environmental impacts. Thus, researchers have suggested replacing lead with tin, known for its lower environmental footprint. Yet, tin tends to oxidize easily, resulting in reduced efficiency and longevity compared to lead-based perovskite alternatives.
To enhance the durability of tin perovskite and mitigate oxidation, a new approach introduces large organic cations into the tin perovskite crystals to create a two-dimensional layered structure known as Ruddlesden-Popper (RP) tin-based perovskites. However, the internal dynamics of this structure and the reasons for its improved performance have not been thoroughly explored.
In this study, researchers applied electron spin resonance to analyze the internal state of an RP perovskite solar cell during operation, providing insights from a microscopic viewpoint.
Perovskite solar cells feature a design where layers for transporting holes and electrons surround a perovskite crystal. Initially, in the absence of light, holes migrated from the hole transport layer into the RP perovskite, causing an energy barrier to form at the interface of the hole transport layer and RP tin perovskite. This barrier curbed the backflow of electrons, ultimately enhancing performance. When exposed to sunlight, electrons transitioned from the RP tin-based perovskite to the hole transport layer, triggered by high-energy electrons arising from short-wavelength light, such as ultraviolet rays. Researchers further observed that this electron movement further increased the energy barrier at the interface, boosting the efficiency of the device.
Grasping the mechanisms that drive performance improvements during operation is essential for advancing the development of effective and long-lasting solar cells, and this understanding will be pivotal for future research endeavors.
This research received support from various Japanese institutions, including the Japan Science and Technology Agency MIRAI (Grants No. JPMJMI20C5, JPMJMI22C1, and JPMJMI22E2), the New Energy and Technology Development Organization, Green Innovation, Japan; and the Japan Society for the Promotion of Science’s Grants-in-Aid for Scientific Research (KAKENHI) (Grant No. 24K01325), among others.
