Queloz Valentin I E, Bouduban Marine E F, García-Benito Ines, Fedorovskiy Alexander, Orlandi Simonetta, Cavazzini Marco, Pozzi Gianluca, Trivedi Harsh, Lupascu Doru C, Beljonne David, Moser Jaques-E, Nazeeruddin Mohammad Khaja, Quarti Claudio, Grancini Giulia
Group for Molecular Engineering of Functional Materials Institute of Chemical Sciences and Engineering Ecole Polytéchnique Fédérale de Lausanne Sion CH-1951 Switzerland.
Photochemical Dynamics Group Institute of Chemical Sciences and Engineering and Lausanne Centre for Ultrafast Science (LACUS) École Polytéchnique Fédérale de Lausanne Lausanne CH-1015 Switzerland.
Adv Funct Mater. 2020 Jul 9;30(28):2000228. doi: 10.1002/adfm.202000228. Epub 2020 May 28.
2D hybrid perovskites (2DP) are versatile materials, whose electronic and optical properties can be tuned through the nature of the organic cations (even when those are seemingly electronically inert). Here, it is demonstrated that fluorination of the organic ligands yields glassy 2DP materials featuring long-lived correlated electron-hole pairs. Such states have a marked charge-transfer character, as revealed by the persistent Stark effect in the form of a second derivative in electroabsorption. Modeling shows that electrostatic effects associated with fluorination, combined with the steric hindrance due to the bulky side groups, drive the formation of spatially dislocated charge pairs with reduced recombination rates. This work enriches and broadens the current knowledge of the photophysics of 2DP, which will hopefully guide synthesis efforts toward novel materials with improved functionalities.
二维杂化钙钛矿（2DP）是用途广泛的材料，其电子和光学性质可通过有机阳离子的性质进行调节（即使这些阳离子看似电子惰性）。在此，研究表明有机配体的氟化可产生具有长寿命相关电子-空穴对的玻璃态2DP材料。如电吸收二阶导数形式的持久斯塔克效应所揭示的，此类态具有显著的电荷转移特性。模型表明，与氟化相关的静电效应，结合庞大侧基引起的空间位阻，促使形成复合率降低的空间错位电荷对。这项工作丰富并拓宽了当前关于2DP光物理的知识，有望指导合成具有改进功能的新型材料的努力。
