近日，美国德克萨斯大学奥斯汀分校的Feliciano Giustino及其研究团队取得一项新进展。经过不懈努力，他们发现卤化物钙钛矿中的拓扑极化子。相关研究成果已于2024年5月17日在国际知名学术期刊《美国科学院院刊》上发表。
通过在长度尺度上进行第一性原理模拟，该研究团队发现卤化物钙钛矿具有独特丰富的极化子种类，包括小极化子、大极化子和电荷密度波，并解释了各种实验观察结果。研究人员发现这些涌现的准粒子支持具有量子化拓扑电荷的拓扑非平凡声子场，使它们成为磁性斯基米子晶格中螺旋布洛赫点的非磁性类比。
据悉，卤化物钙钛矿是一种革命性的高质量半导体，用于太阳能收集和节能照明。越来越多的证据表明，这些材料的特殊光电特性可能源于非常规的电子-声子耦合，并且已经提出极化子和自捕获激子的形成可能是理解这些特性的关键。
附：英文原文
Title: Topological polarons in halide perovskites
Author: Lafuente-Bartolome, Jon, Lian, Chao, Giustino, Feliciano
Issue&Volume: 2024-5-17
Abstract: Halide perovskites emerged as a revolutionary family of high-quality semiconductors for solar energy harvesting and energy-efficient lighting. There is mounting evidence that the exceptional optoelectronic properties of these materials could stem from unconventional electron–phonon couplings, and it has been suggested that the formation of polarons and self-trapped excitons could be key to understanding such properties. By performing first-principles simulations across the length scales, here we show that halide perovskites harbor a uniquely rich variety of polaronic species, including small polarons, large polarons, and charge density waves, and we explain a variety of experimental observations. We find that these emergent quasiparticles support topologically nontrivial phonon fields with quantized topological charge, making them nonmagnetic analog of the helical Bloch points found in magnetic skyrmion lattices.
DOI: 10.1073/pnas.2318151121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2318151121