Premium
Wide‐Bandgap Double Perovskites with Multiple Longitudinal‐Optical Phonon Scattering
Author(s) -
Wang Liangling,
Zheng Wei,
Vitale Francesco,
Zhang Xiangzhou,
Li Xiuling,
Ji Yanchen,
Liu Zhen,
Ghaebi Omid,
Plass Christian T.,
Domes Robert,
Frosch Torsten,
Soavi Giancarlo,
Wendler Elke,
Zhang Yuhai,
Ronning Carsten
Publication year - 2022
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202111338
Subject(s) - materials science , phonon , photoluminescence , exciton , coupling (piping) , band gap , condensed matter physics , optoelectronics , excited state , electron , scattering , atomic physics , optics , physics , quantum mechanics , metallurgy
Alloyed lead‐free double perovskites display intense photoluminescence, are environmentally friendly, and their devices show long‐term operation. Thanks to these properties, which make them excellent warm white‐emitting materials, they have recently received great attention in lighting applications. An important factor to tune the optical properties of alloyed lead‐free double perovskites is the presence of self‐trapped excitons. Here, it is demonstrated that in lead‐free double perovskites, the strong electron–phonon coupling plays a crucial role in the generation of self‐trapped excitons. The strong electron–phonon coupling is confirmed by a large Huang–Rhys factor and by the presence of multiphonon transitions. In particular, sharp emission lines superimposed on the broad photoluminescence emission band of one of these samples (Cs 2 Ag 0.6 Na 0.4 InCl 6 0.5%Bi) are observed; these are due to the strong coupling of longitudinal‐optical phonons with excited electronic states caused by the tetragonally distorted AgCl 6 octahedrons. Such a strong coupling of longitudinal‐optical phonons to electrons can effectively modulate the photophysical properties of alloyed double perovskites, and its understanding is, thus, of paramount importance for the design of future optoelectronic devices.