Publication date: 22nd July 2026
Polarons are believed to play a key role in determining the optoelectronic properties of halide perovskites, yet their microscopic nature remains poorly understood. First principles calculations are challenging because polarons in these materials arise from complex electron-phonon interactions and may extend over several unit cells, beyond the reach of direct supercell approaches.
In this work, we apply the recently developed ab initio theory of polarons to study polaronic quasiparticles in halide perovskites across length scales, focusing on the lead-free double perovskite Cs2AgBiBr6 as a representative example. Our calculations reveal a rich variety of polaronic species, including large polarons, small polarons, and periodic twist-density waves. These results provide a unified microscopic framework for interpreting carrier localization and photoinduced structural distortions in halide perovskites.
We further find that these emergent quasiparticles support topologically nontrivial displacement fields: small electron polarons carry a finite toroidal moment, while large electron and hole polarons form helical Bloch points with finite helicity, making them non-magnetic analogues of the helical Bloch points found in magnetic skyrmion lattices. These topological polarons give rise to characteristic fingerprints in Huang diffuse scattering, suggesting a route to their detection via ultrafast electron and X-ray scattering experiments.
This work was supported by the Computational Materials Sciences Program funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award No. DE-SC0020129. This research used resources of the National Energy Research Scientific Computing Center, a Department of Energy Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We also acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing additional high performance computing resources, including the Frontera and Lonestar6 systems, that have contributed to the research results reported within this work (http://www.tacc.utexas.edu).
Current work in this area by J.L.-B. is supported by Grant No. EHU-N25/24 from the University of the Basque Country (EHU).
nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.
Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.
International Conference on Hybrid and Organic Photovoltaics
International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.
The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.