Efficient Light Emission Modulation of Electron-Phonon Coupling in Sb3+-Doped 2D A(2)CdCl(4) by Varied Amine Molecules

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)(2)CdCl(4 )and (HDM)(2)CdCl4 (BAH = benzylamine hydrochloride; HDM = hexamethylenediamine) by powder X-ray diffraction (XRD); in the former crystal, double BAH layers separate one CdClx layer, while in the latter case, one biamine layer separates two CdClx 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)(2)CdCl4:Sb3+ gives a broad yellow emission band at 590 nm with a photoluminescence quantum yield (PLQY) of 84.6%, while the (HDM)(2)CdCl4: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)(2)CdCl4 can red-shift the STE band emission to a lower energy.