An international collaboration that includes researchers from UNSW, University of Cambridge, Colorado State University, Imperial College London, ANSTO Sydney and synchrotron facilities in Australia, the UK, and Germany recently found that dynamic nanodomains within lead halide perovskites could be vital for boosting their efficiency and stability.
The team examined the nature of these microscopic structures, and how they impact the way electrons are energized by light and transported through the material, offering insights into more efficient solar cells.
The team used single-crystal diffuse scattering and inelastic neutron spectroscopy to directly probe the local structure of MAPbBr3 and FAPbBr3 in reciprocal space. The scientists developed a phenomenological model and ran large-scale machine learning molecular dynamics (MD) simulations that fully reproduce all the experimental features in the diffuse scattering patterns. This approach allowed them to achieve a comprehensive understanding of the local structure in real space, which manifests in the presence of dynamic nanodomains.
Using it, they could accurately quantify their spatial dimensions, assign local symmetry and estimate their density within the material, as well as rule out certain local structural configurations previously proposed in the literature.
They found that the properties of dynamically tilted octahedral pockets, which form transient twinned nanodomains and constitute the local structure, are dictated by the A-site cation. Specifically, methylammonium (MA) cations promote densely packed planar nanodomains with out-of-phase octahedral tilting, whereas FA favors sparse spherical nanodomains with in-phase octahedral tilting.
Hyperspectral photoluminescence (PL) microscopy experiments supported by simulations provide the first direct experimental evidence linking the A-site-cation-driven local structure to the tunability of the macroscopic properties in LHPs.
The team demonstrated that the spherical nanodomains in FA hybrid LHPs lead to superior macroscopic optoelectronic performance of FA over their MA analogues. The control over local order could be leveraged to engineer enhanced optoelectronic properties, potentially driving further advancements in perovskite-based photovoltaics, optoelectronics and X-ray imaging and even other, more exotic device types.
The recent research shows that by understanding the behavior of these nanodomains, scientists could fine-tune the properties of perovskites to improve the performance and longevity of solar cells. Until now, the fluctuating nature of these nanodomains had not been fully understood, but this study suggests that mastering their behavior could enable perovskites to reach their full potential.
Milos Dubajic from the University of Cambridge said: "By understanding the dynamic nature of these nanodomains, we can potentially control their behavior to improve the performance of solar cells and other optoelectronic devices. This could help push the boundaries of energy conversion efficiency."
Professor Sam Stranks, Principal Investigator of the group, added, "This research brings us closer to understanding the intricate nanoscale of these materials. By unlocking the secrets of dynamic nanodomains, we can help accelerate the development of perovskite-based solar technologies and make them a more viable solution for the global push towards renewable energy."
The study builds on the group's wider work in developing more efficient and sustainable energy solutions through material science. By advancing the understanding of materials like lead halide perovskites, the team aims to address global challenges in renewable energy sources like solar power.
