White electroluminescent (EL) emission from single-layered solid-state light-emitting electrochemical cells (LECs) based on host−guest cationic iridium complexes has been successfully demonstrated. The devices show white EL spectra (Commission Internationale de l'Eclairage coordinates ranging (x, y) = (0.45, 0.40) to (0.35, 0.39) at 2.9−3.3 V with high color rendering indices up 80. Peak external quantum efficiency and peak power of the LEC reach 4% 7.8 lm/W, respectively. These results...

We have synthesized three star-shaped 1,3,5-triazine derivatives—2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine (T2T), 2,4,6-tris(triphenyl-3-yl)-1,3,5-triazine (T3T), and 2,4,6-tris(9,9′-spirobifluorene-2-yl)-1,3,5-triazine (TST)—as new electron transport (ET)-type host materials for green phosphorescent organic light-emitting devices. The morphological, thermal, photophysical properties the mobilities of these ET-type are influenced by nature aryl substituents attached to triazene core....

Three Ir-based materials were synthesized through metathesis reaction between halide and alkali metal salts of two cationic three anionic Ir complexes, respectively. The resulting "soft salt" complexes are composed an organometallic cation anion. electrochemical photophysical characterization these compounds is reported. redox potentials the soft shown to be determined by lowest energy ions. Energy transfer ions in solution observed, found take place at diffusion controlled rates. Organic...

In this study, we synthesized a series of bipolar hosts (CbzCBI, mCPCBI, CbzNBI, and mCPNBI) containing hole-transporting carbazole electron-transporting benzimidazole moieties then examined the morphological, thermal, photophysical properties carrier mobilities these host materials. Altering linking topology (C- or N-connectivity benzimidazole) changed effective conjugation length led to different excited-state solvent relaxation behavior. The N-connected compounds (CbzNBI, possessed higher...

We report highly efficient, solid-state, white light-emitting electrochemical cells (LECs) based on a double-doped strategy, which judiciously introduces an orange-emitting guest, [Ir(ppy)2(dasb)]+(PF6−), into single-doped emissive layer comprised of efficient blue-green emitting host, [Ir(dfppz)2(dtb-bpy)]+(PF6−), and red-emitting [Ir(ppy)2(biq)]+(PF6−), to improve the balance carrier mobilities and, thus, enhance device efficiency. Photoluminescence (PL) measurements show that (red guest)...

We demonstrate the improving balance of carrier mobilities in neat-film light-emitting electrochemical cells (LECs) utilizing a cationic transition metal complex (CTMC) as emissive material and near-infrared laser dye trapper. This low-gap trapper is judiciously chosen such that significant energy offset highest occupied molecular orbital (HOMO) levels between CTMC impedes hole transport layers while similar lowest unoccupied (LUMO) these two materials result relatively unaffected electron...

Solid-state white light-emitting electrochemical cells (LECs) have attracted research attention owing to their advantages of simple device structure, low operation voltage and compatibility with solution processes. In this work, we demonstrate a approach obtain electroluminescence (EL) from non-doped LECs based on blue-emitting complex. With relatively thicker emissive layer, red emission can be additionally enhanced by the microcavity effect when recombination zone moves appropriate...

We report phosphorescent sensitized fluorescent near-infrared (NIR) light-emitting electrochemical cells (LECs) utilizing a cationic transition metal complex [Ir(ppy)2(dasb)]+(PF6−) (where ppy is 2-phenylpyridine and dasb 4,5-diaza-9,9′-spirobifluorene) as the host two ionic NIR emitting dyes 3,3′-diethyl-2,2′-oxathiacarbocyanine iodide (DOTCI) 3,3′-diethylthiatricarbocyanine (DTTCI) guests. Photoluminescence measurements show that host–guest films containing low guest concentrations...

Highly efficient exciplex emission in solid-state light-emitting electrochemical cells (LECs) was achieved by mixing two ionic fluorescent emitters with opposite bipolarity. A triarylamine derivative as a hole-transport material (HTM) and 1,3,5-triazine an electron-transport (ETM) were selected due to their superior carrier mobilities. The character of HTM ETM chemically attaching three pendant methylimidazolium groups peripheries, rendering them amenable LEC applications. Strong green can...

Two anionic iridium complexes Na[Ir(2-(p-tolyl)pyridine)2(CN)2] (A1) and Na[Ir(2-phenylquinoline)2(CN)2] (A2) were synthesized characterized for use in light-emitting electrochemical cells (LECs). The photophysical studies show that the emission wavelengths LUMO energy levels of these are governed by conjugation length cyclometalated ligands. Single-layer LEC devices incorporating fabricated tested. Suffering from poor solubility complexes, device performances rather limited due to lack film...

Efficient phosphorescent sensitized white light-emitting electrochemical cells (LECs) based on a blue-emitting cationic transition metal complex (CTMC) doped with red-emitting fluorescent dye are demonstrated. Blue phosphorescence and phosphorescence-sensitized red fluorescence contribute to emission. Furthermore, the microcavity effect of device structure is utilized suppress green part electroluminescence (EL) spectrum (1) via destructive interference. Hence, more saturated blue EL...

A systematic comparison of the physical properties and dual-role (host electron transport) applications star-shaped 1,3,5-triazine-based ET-type hosts (T2T, 3N-T2T, 3P-T2T, oCF3-T2T) with differential peripheral groups was reported. The introduction N-heterocyclic polar peripheries onto a 1,3,5-triazine core gave evident benefits to injection/transport properties, rendering efficient PhOLEDs simpler device configuration feasible. Among these hosts, 3P-T2T can serve both as promising host...

In this study, we obtained saturated deep-blue electroluminescence (EL) from solid state light-emitting electrochemical cells (LECs) incorporating the ionic terfluorene derivative 1, which synthesized through covalent tethering of methylimidazolium moieties as pendent groups terfluorene. Compound 1 exhibited emission, extremely high quantum yield, and reversible redox behavior that are characteristic derivatives. LEC devices EL with CIE coordinates (0.159, 0.115) (0.151, 0.122) in absence...

We study the influence of carrier injection efficiency on performance light-emitting electrochemical cells (LECs) based a hole-preferred transporting cationic transition metal complex (CTMC) [Ir(dfppz)2(dtb-bpy)]+(PF6−) (complex 1) and an electron-preferred CTMC [Ir(ppy)2(dasb)]+(PF6−) 2) (where dfppz is 1-(2,4-difluorophenyl) pyrazole, dtb-bpy 4,4′-di(tert-butyl)-2,2′-bipyridine, ppy 2-phenylpyridine dasb 4,5-diaza-9,9′-spirobifluorene). Experimental results show that even with...

White LECs containing embedded red color conversion layers exhibit EQE and power efficiency of up to 12.5% 27 lm W⁻¹, respectively.

Device efficiency of white LECs can be enhanced by recycling the trapped EL in ITO layer to forward direction.

We report a significant decrease in turn-on times of light-emitting electrochemical cells (LECs) by tethering imidazolium moieties onto cationic Ir complex. The introduction two groups at the ends alkyl side chains [Ir(ppy)(2)(dC6-daf)](+)(PF(6))(-) (ppy = 2-phenylpyridine, dC6-daf 9,9'-dihexyl-4,5-diazafluorene) gave complex [Ir(ppy)(2)(dC6MIM-daf)](3+)[(PF(6))(-)](3) (dC6MIM-daf 9,9-bis[6-(3-methylimidazolium)hexyl]-1-yl-4,5-diazafluorene). Both complexes exhibited similar...

We report efficient host-guest solid-state light-emitting electrochemical cells (LECs) utilizing a cationic terfluorene derivative as the host and red-emitting transition metal complex guest. Carrier trapping induced by energy offset in lowest unoccupied molecular orbital (LUMO) levels between guest impedes electron transport films thus improves balance of carrier mobilities intrinsically exhibiting preferred transporting characteristics. Photoluminescence measurements show transfer this...

Cationic iridium complexes incorporated 4,5-diaza-9,9'-spirobifluorene as N(∧)N ancillary ligands, in which one (2) or two (3) phenyl groups were introduced onto 4,5-diazafluorene to afford intraligand π-π interactions. The X-ray crystal structures of 2 and 3 show that the pendant ring forms strong intramolecular face-to-face π-stacking with difluorophenyl cyclometalated ligand distances 3.38 Å for complex 3.40 3.46 3. This stacking interaction minimizes expansion metal-ligand bonds excited...

We report highly efficient phosphor-sensitized solid-state light-emitting electrochemical cells (LECs) utilizing a phosphorescent cationic iridium complex [Ir(dFppy)2(SB)]+(PF6−) as the host and fluorescent dye (R6G) guest. Photophysical studies show that R6G retains high photoluminescence quantum yield (PLQY) in polar media, revealing its suitable use an emitting guest ionic matrix. Such LECs achieve efficiency (cd A−1) efficiency, power up to 5.5% photon/electron, 19 cd A−1 21.3 lm W−1,...