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Halide Double‐Perovskite Light‐Emitting Centers Embedded in Lattice‐Matched and Coherent Crystalline Matrix
Author(s) -
Dai ChenMin,
Zhang Tao,
Wu YuNing,
Chen Shiyou
Publication year - 2020
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.202000653
Subject(s) - materials science , photoluminescence , band gap , direct and indirect band gaps , halide , optoelectronics , heterojunction , perovskite (structure) , lattice constant , exciton , spontaneous emission , condensed matter physics , optics , diffraction , crystallography , physics , laser , inorganic chemistry , chemistry
Through first‐principles calculations, it is found that two lattice‐matched halide double‐perovskites, Cs 2 NaBiBr 6 and Cs 2 AgBiBr 6 , have a type‐I band alignment and can form highly miscible alloys in which the disordering makes the bandgaps become direct and activates the direct transition from the valence to conduction band edge, leading to a strong optical absorption and high radiative recombination rate. The bandgaps of the alloys are tunable in a wide range of 1.93–3.24 eV, while the lattice constants remain unchanged. This advantage inspires the design of a coherent crystalline matrix based on Cs 2 (Na,Ag)BiBr 6 alloys, in which the Ag‐rich and narrower‐bandgap regions are embedded in the Na‐rich and wide‐bandgap region with lattice‐matched and coherent interfaces. The type‐I band alignment drives the photogenerated excitons into the narrower‐bandgap Ag‐rich regions, so the regions become light‐emitting centers with a high photoluminescence quantum yield (PLQY). The bandgaps of the Ag‐rich regions are tunable, so the color of emitted light can be adjusted, making a broadband emission possible. Such kind of coherent crystalline matrix with high‐PLQY and broadband emission can also be fabricated based on the alloys of other lattice‐matched halide double‐perovskites, demonstrating the flexibility of band structure engineering in the coherent heterostructures of various halide double‐perovskites.