Localized optical absorption in Cs₄PbBr₆

Abstract

The fundamental optical absorption of Cs 4 PbBr 6 crystals, which are built up of nearly regular Pb 2+ (Br − ) 6 octahedra mutually bound by Cs + ions, exhibits novel features: despite the crystalline entity of Cs 4 PbBr 6 , it shows oscillatorlike absorption peaks and a wide window just above the first peak. The Cs + ions prevent the Pb 2+ 6s and 6p states from taking part in the construction of extended states. These states form a set of localized states confined to within respective octahedra, similar to the case of isolated Pb 2+ ions doped in face-centred cubic alkali halide crystals.

Pressure-induced emission of cesium lead halide perovskite nanocrystals

“…The calculated total and partial densities of states demonstrate that the valence bands primarily originate from the hybridization between the 6s orbital of Pb and the 4p orbital of Br, while the conduction band is mainly contributed by the 6p orbital of Pb. The steady-state PL of samples was obtained under ambient conditions, and no emission was observed, consistent with previous reports on bulk Cs 4 PbBr 6 powders and films 19,20 . The absence of luminescence at room temperature of Cs 4 PbBr 6 has been attributed to the thermal quenching effect 8,19 that may be caused by exciton migration 21 , nonradiative recombination processes involving phonons 19 , etc.…”

Probing molecule-like isolated octahedra via phase stabilization of zero-dimensional cesium lead halide nanocrystals

“…The complete isolation of octahedra leads to strong quantum confinement and exciton–phonon interactions, which in turn can result in exciton localization, self-trapping, and polaron formation 10 . The optical features of 0D Cs 4 PbX 6 are governed by transitions between the electronic states of Pb 2+ ions, and its broad ultraviolet (UV) emission has been assigned to the radiative decay of Frenkel excitons at Pb 2+ sites 11–15 . However, the origin of their PL in the visible range is still under debate because of mixed views on the efficient green luminescence (QY of 45%) of Cs 4 PbBr 6 , which some studies have been attributed to the minor 3D CsPbBr 3 nanoscale impurity 3,16–18 .…”

Growth and characterization of pure and Pr3+-doped Cs4PbBr6 crystals

“…Pb-Br 1,2,3,4,5,6 3.0281(5) Cs(2)-Br 11,1,3,14,15, 6 3.5657(6) Cs(1)-Br 7, 8 3.6943(6) Cs(1)-Br 9, 10 3.7019(6) Cs(1)-Br 6, 11 3.7497(6) Cs(1)-Br 12, 13 3.8243 (7) thick after manual polishing. The Pr 3+ ions content that was measured in the crystal displayed in Fig.…”

“…Cs 4 PbBr 6 is a long-time known bromide [9] that, among several alkalibased lead bromides, has been investigated in the form of bulk crystals and thin films for its particular optical properties arising from the 6s 2 Pb 2+ cations electronic outer shell [10,11]. In the course of our experiments, we became interested in doping this material with Pr 3+ cations in order to investigate its spectroscopical properties in the 1-5 mm spectral range.…”