Hybrid Organic–Inorganic Halides (C₅H₇N₂)₂MBr₄ (M = Hg, Zn) with High Color Rendering Index and High-Efficiency White-Light Emission

Abstract

Low-dimensional hybrid organic–inorganic materials (HOIMs) are being widely investigated for their unique optoelectronic properties. Some of them exhibit broadband white-light (WL) luminescence upon UV excitation, providing a potential for the fabrication of single-component white-light-emitting diodes. Here, we report new examples of low-dimensional HOIMs, based on 4-aminopyridinium (4AMP) and group 12 metals (Hg and Zn), for single-component WL emission. The 4AMP cation containing structures feature HgBr4 and ZnBr4 isolated tetrahedra in (C5H7N2)2HgBr4·H2O (1) and (C5H7N2)2ZnBr4 (2), respectively. The presence of isolated molecular units in the zero-dimensional structures results in strongly localized charges and bright WL luminescence with corresponding Commission Internationale de l’Eclairage color coordinates of (0.34, 0.38) and (0.25, 0.26), correlated color temperatures of 5206 K (1) and 11 630 K (2), and very high color rendering indexes (CRI) of 87 (1) and 96 (2). The visibly bright WL emission at room temperature is corroborated with high measured photoluminescence quantum yield values of 14.87 and 19.18% for 1 and 2, respectively. Notably, the high CRI values for these new HOIMs exceed the commercial requirements and produce both “warm” and “cold” WL depending on the metal used (Hg or Zn). Based on temperature- and powder-dependent photoluminescence (PL), PL lifetimes measurements and density functional theory calculations, the broadband WL emission is assigned to the 4AMP organic molecules emission and self-trapped states.

Doped Lead Halide White Phosphors for Very High Efficiency and Ultra‐High Color Rendering

“…Furthermore,t he corresponding correlated color temperatures (CCT) can be tuned from 7034 Kt o 4188 K ( Figure 2c), and the photoluminescence quantum yield (PLQY) can reach 68 %( Supporting Information, Table S3). Among these samples,T PbBr-3 (Mn content of 0.027 %) is particularly interesting.I ts CRI reaches 96 corresponding to the record CRI for as ingle phase emitter, [25,41,42] the CIE coordinate (0.330, 0.365) corresponds to pure white light, and the PLQY reaches 60 %which is anew record for lead halide white emitter (Figure 2c< xfigr2). [17,20-22, 25, 43] Even if other compounds such as (H 2 DABCO)(Pb 2 Cl 6 )a nd (C 5 H 7 N 2 ) 2 SnBr 4 were reported…”

“…Research Articles with CRI close to 96, the intensity of their emissions remained very low (PLQY < 3%) [41] or did not correspond to ap ure white light. [42] Besides,i ti si mportant to note that the CRI value is merely an index which only considers the first eight (R1-R8) color samples.F or TPbBr-3, all the values from R1 to R14 are above 90, which is exceptional for as ingle-phase phosphor (Figure 2d). Fore xample,R 9r eflecting the color reproduction in the strong red region, is very important for biomedical and painting applications.…”

Optical Functional Units in Zero‐Dimensional Metal Halides as a Paradigm of Tunable Photoluminescence and Multicomponent Chromophores

“…The transformation of the M‐position cations hardly affect the emission peak, which make it easy for us to attribute the emission center to the [Pb 3 X 11 ] 5− clusters. Many recent studies show that organic cations may also contribute to the emission in hybrid metal halides; with the aim of determining the role of organic cations in the PL process, we also provided the PL comparison between the organic salt and selected samples (Figure S4, Supporting Information) 8. As shown in the results, the two organic salts exhibit negligible emission compared to the title compounds (about 50 times lower than Zn–Br sample and 300 times lower than Zn–Cl sample).…”

Electronic and optical properties of zinc based hybrid organic-inorganic compounds

“…The results are still applicable because varying the ratio would vary the bandgap values, but the band dispersion and the pattern of density of states (DOS) would remain similar. Results show that among the list of thirteen Zn-HOI compounds, CuZnO 2 (CO 3 ) (Z3) and Zn 8 (HPO 4 ) 16 (C 2 H 8 N) 8 The scale of DOS is adjusted in order to bring out the hybridization features more prominently. The zero in the energy axis refers to the Fermi level.…”

“…Majority of the work on the development of HOI materials for electronic technology research is focused on perovskite HOIs with the general chemical formula ABO 3. Common examples include, CH 3 NH 3 PbI 3 and CH 3 NH 3 PbBr 3, which are actively investigated for their photovoltaic properties [6]. HOIs have been stabilized with various organic functional groups, such as halides, formates, dyanides, dicyanamides, amides and dicyanometallates [1,7,8]. Ferroelectric properties have been explored for [(CH 3 ) 2 NH 2 ][M(HCOO) 3 ] with M=Mg, Fe, Co, Ni, Cu, or Zn, where polarizations in the range 0.6 μC cm −2 -6 μC cm −2 have been observed [9][10][11][12][13].…”