Regulating photoluminescence through single-crystal-to-single-crystal transformation of solvent-containing zero-dimensional hybrid metal halide isomers

Here reports the first example of single-crystal-to-single-crystal transformation between two zero-dimensional metal halide isomers containing lattice solvent molecules, which leads to the regulation of the photoluminescence performance and optimization of white LED device. [Display omitted] •The first example of single-crystal-to-single-crystal (SCSC) transformation between two isomers containing lattice solvent molecules in zero-dimensional metal halides.•Regulating photoluminescence (PL) properties has been realized by SCSC transformation.•The mechanisms of title compounds’ PL emission and the PL regulation brought by SCSC transformation have been clarified.•Benefitting from the PL regulation brought by SCSC transformation, the white LED device has been optimized and its CRI has reached as high as 95.3. Regulating photoluminescence (PL) properties induced by single-crystal-to-single-crystal (SCSC) transformation has sparked significant interest in the research of zero-dimensional organic–inorganic metal halides (0-D OIMHs). To best of our knowledge, the SCSC transformation of solvent-containing 0-D OIMH isomers hasn’t been reported yet. In this work, we report the first example of SCSC transformation between two isomers containing lattice solvent molecules, namely α- and β-[EtPPh3]2[SbCl5]·MeCN (α- and β-1·MeCN; EtPPh3 = ethyltriphenylphosphonium; MeCN = acetonitrile). Differential scanning calorimetry (DSC) results show that the SCSC transformation from α- to β-1·MeCN is an exothermic process, implying that β-1·MeCN is a more stable phase than α-1·MeCN. Moreover, α- and β-1·MeCN exhibit bright orange (emission peak: 610 nm) and red (emission peak: 635 nm) emission under 360/365 nm excitation, respectively. DFT calculations suggest that the negligible self-absorption and a strong exciton confinement contribute to their effective PL emission. By analyzing temperature-dependent PL spectra, β-1·MeCN has been found to exhibit stronger electron-phonon coupling under excitation than α-1·MeCN. Thus, the broader emission with full width at half maximum (FWHM: 134 vs. 147 nm) and the higher photoluminescence quantum yield (PLQY: 40.37% vs. 70.50%) have been realized by SCSC transformation from α- to β-1·MeCN by heating at 92 °C. Benefitting from the regulation of PL performances brought by SCSC transformation, the white light-emitting-diode (LED) devices assembled by using β-1·MeCN as red phosphor could be optimized, and the CRI reaches as high as 95.3.