A synergetic model for implementing single-component white-light emission: a case study of zero-dimensional cadmium halides

• Published in: Materials chemistry frontiers Vol. 7; no. 4; pp. 75 - 712
• Main Authors: Yuan, Jiantao, Zhou, Guojun, Zhang, Jian, Zhang, Xian-Ming
• Format: Journal Article
• Language: English
• Published: London Royal Society of Chemistry 13.02.2023
• Subjects: Broadband; Bromine; Cadmium; Emission analysis; Emitters; Excitons; Halogens; Ligands; Light emission; Metal halides; Photoluminescence; Tetrahedra; Transmutation; Trapping; White light
• ISSN: 2052-1537; 2052-1537
• DOI: 10.1039/d2qm01049f

Although low-dimensional hybrid metal halides have recently been the subject of considerable attention as white-light emitters, the superiority of structural diversity has not been relied upon to tune photoluminescence (PL) behaviors by synergistic control of organic and inorganic compositions. Herein, a series of distinctive cadmium halides (C 6 H 7 NX) 2 CdX 4 (X = Cl, Br, I) with π-conjugated ligands and halogen substitution are developed, in which the isolated [CdX 4 ] 2− tetrahedrons are separated by large [C 6 H 7 NX] + organic cations into a unique zero-dimensional (0D) host-guest structure. Intriguingly, the synergetic controlling of π-conjugated ligands and [CdX 4 ] 2− units enables single-component ultra-broadband white-light emissions with a record color rendering index (CRI) of 99 in the above novel 0D cadmium halides. (C 6 H 7 NCl) 2 CdCl 4 and (C 6 H 7 NBr) 2 CdBr 4 exhibit ultra-broadband cold white-light emission with large full-width at half-maximum (FWHM) of 218 nm and 244 nm, respectively, which is triggered by the synergistic emissions of [C 6 H 7 NX] + ligands and self-trapped excitons (STEs) of Cd 2+ . A comparison of PL properties of cadmium halides with Cl/Br/I transmutation elucidated that the nature of the halogens is strongly dependent on the trapping/de-trapping of STEs as well as on the π → π* transition of the π-conjugated ligands, along with the resulting PL modulation on emission intensities, wavelengths, and FWHM. This work reveals a unique synergetic model for implementing white-light emission and extends to the design of high-performance hybrid emitters. A serial of 0D (C 6 H 7 NX) 2 CdX 4 (X = Cl, Br, I) are developed, and the synergetic controlling of π-conjugated ligands and [CdX 4 ] units enables single-component ultra-broadband white-light emissions of (C 6 H 7 NCl) 2 CdCl 4 and (C 6 H 7 NBr) 2 CdBr 4 .