In recent years, two-dimensional (2D) perovskite materials
have
attracted much attention due to their excellent photoelectric properties.
We successfully synthesized Sb3+-doped 2D cadmium-based
organic amine hybrid perovskites (BAH)2CdCl4 and (HDM)2CdCl4 (BAH = benzylamine hydrochloride;
HDM = hexamethylenediamine) by powder X-ray diffraction (XRD); in
the former crystal, double BAH layers separate one CdCl
x
layer, while in the latter case, one biamine layer
separates two CdCl
x
layers. The Sb doping
resulted in a red shift in their absorption band edge in both samples
and gave efficient broad-band orange-yellow emission bands at room
temperature from the self-trapped exciton (STE) state of the triplet
of Sb3+ ions in the lattice. (BAH)2CdCl4:Sb3+ gives a broad yellow emission band at 590
nm with a photoluminescence quantum yield (PLQY) of 84.6%, while the
(HDM)2CdCl4:Sb3+ system has an emission
band at 570 nm with the PLQY at 99.97%, which occurs for samples at
increasing growth temperatures with reduced impurity phase and improved
crystalline phase purity and emission intensity due to the higher
rigidity. The heterovalent substitution results in significant crystal
field variations, which helps promote electron–phonon coupling,
STE formation, and related emission. The high electron–phonon
coupling coefficients in (BAH)2CdCl4 can red-shift
the STE band emission to a lower energy.