Electroluminescent Properties of LECs Based on Ionic Transition Metal Complexes Using Tetrazole-Based Ancillary Ligand

Molecular Engineering of Ionic Transition Metal Complexes and Counterions for Efficient Flexible Green Light-Emitting Electrochemical Cells

“…385 nm (λ abs,2 ), corresponds to either metal-to-ligand charge transfer (MLCT) or ligand-to-ligand charge transfer (LLCT) transitions. Noteworthy, the UV–vis spectrum of the synthesized complex is similar to the one of the homologue Ir-cyclometalated complex. − The PL emission spectra of the Ir complex were obtained by exciting the electron with an excitation wavelength of 405 nm. The PL spectrum of the Ir complex in CH 3 CN solution shows a green emission peaking at ca .…”

Versatile Electroluminescence Color-Tuning Strategy of an Efficient Light-Emitting Electrochemical Cell (LEC) by an Ionic Additive

“…The turn-on time (measured at 5 V) decreased from 351.6 s (the additive-free device) to less than 115.1 s for the films blended with LiTFSI and 206.3 s for TBAP. Because turn-on times are dependent upon counterion mobility within the iTMC film, − the high mobility and high intrinsic conductivity of LiTFSI reduced device turn-on time to the minimum value. − The improvement in T on was attributed to the increased ionic mobility upon blending with additives. Also, as shown in Figure a and Table , both of the additives led to stability improvement in comparison with additive-free LEC.…”

“…It is useful to note that the conversion of the neutral Ir­(ppy) 2 (BrTz) into its methylated and positively charged [Ir­(ppy) 2 (BrTz-Me)] + counterpart brought to us efficient LEC devices and involved further modifying of their luminescence output. The initial iTMC emitter is currently used as the active layer without any additive and resulted in an orange electroluminescence color (576 nm) with CIE coordinates of (0.45, 0.49) . The EL emission observed for LiTFSI and TBAP-based devices is broad and centered at 565 and 547 nm, respectively.…”

“…The insertion of a methyl substituent into the coordinated tetrazolate ring retained the absorption profile by the small blue shift of the whole spectrum. 39,55 As shown in Figure 1a, the RT absorption spectra of these complexes in MeCN and in the UV region display intense absorption bands, which are assigned to the spinallowed ligand-centered (LC) transitions of both the ancillary and cyclometalated ligands, accompanied by the shoulders appearing in longer wavelengths that correspond to spinforbidden metal-to-ligand charge-transfer (MLCT), ligand-toligand charge-transfer (LLCT), and LC transitions. 55 Upon excitation of these complexes (λ exc = 405 nm) in both the solution and solid film, the neutral and cationic complexes show intense and featureless bands with emission maxima occurring between the wavelengths of 540−550 and 551−560 nm (Figure 1a and Table 1), respectively, originating from the excited states of the triplet character.…”

“…39,55 As shown in Figure 1a, the RT absorption spectra of these complexes in MeCN and in the UV region display intense absorption bands, which are assigned to the spinallowed ligand-centered (LC) transitions of both the ancillary and cyclometalated ligands, accompanied by the shoulders appearing in longer wavelengths that correspond to spinforbidden metal-to-ligand charge-transfer (MLCT), ligand-toligand charge-transfer (LLCT), and LC transitions. 55 Upon excitation of these complexes (λ exc = 405 nm) in both the solution and solid film, the neutral and cationic complexes show intense and featureless bands with emission maxima occurring between the wavelengths of 540−550 and 551−560 nm (Figure 1a and Table 1), respectively, originating from the excited states of the triplet character. 56,57 Inspired by recent reports, the conversion of the neutral Ir(III)-tetrazolato complex into its methylated and positively charged counterpart was accompanied by a red shift of the emission spectrum.…”