Gao Lei, Zhang Heng, Zhang Yong, Fu Shuai, Geuchies Jaco J, Valli Donato, Saha Rafikul Ali, Pradhan Bapi, Roeffaers Maarten, Debroye Elke, Hofkens Johan, Lu Junpeng, Ni Zhenhua, Wang Hai I, Bonn Mischa
Key Laboratory of Quantum Materials and Devices of Ministry of Education, School of Physics, Southeast University, Nanjing, 211189, China.
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
Adv Mater. 2024 Oct;36(40):e2406109. doi: 10.1002/adma.202406109. Epub 2024 Aug 27.
Charge carriers in the soft and polar perovskite lattice form so-called polaron quasiparticles, charge carriers dressed with a lattice deformation. The spatial extent of a polaron is governed by the material's electron-phonon interaction strength, which determines charge carrier effective mass, mobility, and the so-called Mott polaron density, that is, the maximum stable density of charge carriers that a perovskite can support. Despite its significance, controlling polaron dimensions has been challenging. Here, experimental substantial tuning of polaron dimensions is reported by lattice engineering, through Pb/Sn substitution in CHNHSnPbI. The polaron dimension is deduced from the Mott polaron density, which can be composition-tuned over an order of magnitude, while charge carrier mobility occurs through band transport, and remains substantial across all compositions, ranging from 10 s to 100 s cm V s at room temperature. The effective modulation of polaron size can be understood by considering the bond asymmetry after carrier injection as well as the random spatial distribution of Pb/Sn ions. This study underscores the potential for tailoring polaron dimensions, which is crucial for optimizing applications prioritizing either high charge carrier density or high mobility.
在柔软且具有极性的钙钛矿晶格中，电荷载流子形成所谓的极化子准粒子，即伴随着晶格变形的电荷载流子。极化子的空间范围由材料的电子 - 声子相互作用强度决定，该强度决定了电荷载流子的有效质量、迁移率以及所谓的莫特极化子密度，即钙钛矿能够支持的电荷载流子的最大稳定密度。尽管其具有重要意义，但控制极化子尺寸一直具有挑战性。在此，通过在CHNHSnPbI中进行Pb/Sn替代的晶格工程，报道了对极化子尺寸的实验性大幅调控。极化子尺寸由莫特极化子密度推导得出，其可在一个数量级范围内进行成分调节，而电荷载流子迁移率通过能带输运实现，并且在所有成分中都保持可观，在室温下范围从10 到100 s cm V s。通过考虑载流子注入后的键不对称性以及Pb/Sn离子的随机空间分布，可以理解极化子尺寸的有效调制。这项研究强调了定制极化子尺寸的潜力，这对于优化优先考虑高电荷载流子密度或高迁移率的应用至关重要。
