Effect of hydrostatic pressure on the structural, elastic, and optoelectronic properties of vacancy-ordered double perovskite Cs2PdBr6

Ultrafast Carrier Dynamics and Electrical Properties of the Palladium-Based Vacancy-Ordered Perovskite Cs2PdBr6

“…The positions of the bleach bands agree well with those of the absorption bands predicted by previous DFT calculations for Cs 2 PdBr 6 by Zhao et al In addition, we observe transient induced absorption bands at 335 nm (3.70 eV), 505 nm (2.46 eV), 600 nm (2.07 eV), and 1500 nm (0.83 eV), which likely arise from the absorption of hot carriers in the conduction band. On time scales up to 4 ps (Figure c), we see a combination of an absorption increase and a decay of spectral bands in the 370–930 nm region.…”

“…We observe the appearance of three pronounced bleach bands at 295 nm (4.20 eV), 430 nm (2.88 eV), and 780 nm (1.59 eV) and a weaker one at 560 nm (2.21 eV), which coincide with corresponding features in the inverted steady-state absorption spectrum and the second derivative of the steady-state absorption spectrum (Figure e). The lowest-energy bleach band centered at 1.59 eV is associated with the first direct transition of Cs 2 PdBr 6 , which is close to the indirect band gap. ,, The energetic position is in favorable agreement with previous experimental studies for Cs 2 PdBr 6 films and DFT calculations using the HSE06 functional. − …”

“…The lowest-energy bleach band centered at 1.59 eV is associated with the first direct transition of Cs 2 PdBr 6 , which is close to the indirect band gap. 8,9,11 The energetic position is in favorable agreement with previous experimental studies for Cs 2 PdBr 6 films and DFT calculations using the HSE06 functional. 8−11 The positions of the bleach bands agree well with those of the absorption bands predicted by previous DFT calculations for Cs 2 PdBr 6 by Zhao et al 11 In addition, we observe transient induced absorption bands at 335 nm (3.70 eV), 505 nm (2.46 eV), 600 nm (2.07 eV), and 1500 nm (0.83 eV), which likely arise from the absorption of hot carriers in the conduction band.…”

“…The first direct transition (X → X) is located only 40 meV higher. A much better agreement with respect to the size of the band gap can be obtained by using a higher-level functional, such as HSE06; − however, the current level of theory is appropriate to predict the ground-state phonon frequencies of crystalline Cs 2 PdBr 6 with sufficient accuracy.…”

“…The PL decays of the powder showed a lifetime of about 1 ns, whereas the film exhibited a lifetime of about 80 ns . Several DFT calculations using the HSE06 functional suggested that Cs 2 PdBr 6 has an indirect band gap in the range 1.56–1.71 eV (Γ → X) and that the first direct transition (X → X) is only 20–30 meV away. − In contrast, the DFT calculations of Wang et al predicted a direct band gap of 1.566 eV at the Γ point, with no indirect transition even close in energy . Later on, Zhou et al reported the synthesis of Cs 2 PdBr 6 nanocrystals with an average particle diameter of 2.6 nm using an antisolvent approach.…”