Bismuth-based halide double perovskite Cs2KBiCl6: Disorder and luminescence

Alloying strategy for developing a single-band warm white emitting material Cs2NaGdCl6:Bi3+via Ag+ co-doping

“…Thus Ag + doping in CNGC disrupts the crystal symmetry, induces local distortions, modifies the crystal field, and ultimately enables previously forbidden transitions of Bi 3+ ions to occur, leading to observable luminescence. 5,7,[22][23][24][25][26] It can be observed that when the Ag + doping concentration is 1% and 5%, the emission peaks at 470 nm (attributed to the STEs of the host matrix) and 580 nm (emission from Bi 3+ s-p transition in the alloyed matrix) coexist under 280 nm excitation (Fig. 3b).…”

“…Moreover, dipole-forbidden transitions such as the transitions from 1 S 0 to 3 P 2 and 1 S 0 to 3 P 0 are forbidden at the dipole transition level but the lattice deformation can induce the forbidden transitions to become allowed transitions. 8,21–24…”

“…Thus Ag + doping in CNGC disrupts the crystal symmetry, induces local distortions, modifies the crystal field, and ultimately enables previously forbidden transitions of Bi 3+ ions to occur, leading to observable luminescence. 5,7,22–26…”

Hexagonal Halide Perovskite Cs2LiInCl6: Cation Ordering, Face‐Shared Octahedral Trimers and Mn2+ Luminescence

“…The other three bands do not match the absorption bands of the UV-vis spectra and can be assigned the direct excitation of the electrons from the Mn 2 + ground state 6 A 1 (6S) to higher energy levels within the 3d manifold 4 T 1 (4P), 4 T 2 (4D), and 4 T 2 (4G), similar to that in the Cs 2 LiBiCl 6 :Mn 2 + and Cs 2 KBiCl 6 :Mn 2 + . [20,47] To confirm the aforementioned quenching effect, the decay of the emission originating from the 4 T 1 ! 6 A 1 transition (at 610-622 nm) was recorded for all the Mn 2 + doped samples (Figure 6).…”

“…This is reasonable considering that Mn replaces both Li and corner-sharing In sites, which are crystallographically inequivalent and may lead to two different luminescence relaxation pathways, similar to those observed in Cs 2 KBiCl 6 :Mn 2 + materials. [47] The parameters derived from our analysis are listed in Table S3. The average decay times < τ > are calculated according to the following equation:…”