Efficient Light Emission Modulation of Electron–Phonon Coupling in Sb³⁺-Doped 2D A₂CdCl₄ by Varied Amine Molecules

Abstract

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.

Dopant effect on the optical and thermal properties of the 2D organic–inorganic hybrid perovskite (HDA)2PbBr4

“…Such a significant Stokes shift and FWHM indicate that the emission peak at 533 nm originates from STE emission. 53 Under 375 nm excitation, with increasing temperature, the intensity of the 410 nm peak slightly increases. This behavior is similar to that observed in Mn- 1 and is primarily attributed to thermal activation of the captured excitons.…”