Low-Turn-On-Voltage, High-Brightness, and Deep-Red Light-Emitting Electrochemical Cell Based on a New Blend of [Ru(bpy)₃]²⁺ and Zn–Diphenylcarbazone

Abstract

Deep red light-emitting electrochemical cells were prepared based on a blend of [Ru(bpy) 3 ] 2+ , a cationic complex, and a neutral Zn(II)-complex based on diphenylcarbazone ligands, named Zn(DPCO). The crystal structure of the Zn(DPCO) 2 (bpy)] molecule revealed that the DPCO ligand has been deprotonated to form DPCO – and coordinated to the Zn center metal through the C=O and N=N moieties of DPCO. From the cyclic voltammetry results and controlled potential coulometry data of the diphenylcarbazide (DPC) ligand, it is possible to establish that DPC is oxidized in an irreversible process at +0.77 V, giving DPCO and later oxidized at a higher potential (+1.32 V) to produce diphenylcarbadiazone (DPCDO). A detailed assignment of UV–vis spectra futures to determine the origin of ground- and excited-state transitions was achieved by time-dependent density functional theory calculations, which showed good agreement with the experimental results. Using a simple device architecture, we obtained deep red electroluminescence (EL) with high brightness (740 cd m –2 ) and luminous efficiency of 0.39 cd/A at a low turn-on voltage of 2.5 V. The favorable configuration of the cell consists of only a blend of complexes of indium tin oxide as the anode electrode and molten alloy cathode (Ga/In) without any polymer as the transporting layer. The comparison between [Ru(bpy) 3 ] 2+ and [Ru(bpy) 3 ] 2+ /Zn(DPCO) demonstrates a red shift in the EL wavelength from 625 to 700 nm in the presence of Zn(DPCO), revealing the importance of using blends for future systems.

Long‐Wavelength Light‐Emitting Electrochemical Cells: Materials and Device Engineering

“…(Figure 20). [152] Since a high barrier is present at the 20) in 2020. [153] In this work, a novel cationic ruthenium complex 117 was used to replace the previous cationic zinc complex Chemistry-A European Journal 0.93 %).…”

“…found electroplex emission in the LECs based on the blend of [Ru(bpy) 3 ][ClO 4 ] 2 /complex 116 (Figure 20). [152] Since a high barrier is present at the [Ru(bpy) 3 ][ClO 4 ] 2 /complex 116 interface, carriers would accumulate there to form red‐shifted electroplex emission. With incorporation of complex 116 , the EL emission peak moved from 625 nm for [Ru(bpy) 3 ][ClO 4 ] 2 emission to ca.…”

Zinc (II) and AIEgens: The “Clip Approach” for a Novel Fluorophore Family. A Review

“…The same material resulted emissive both in the solid phase and mixed with an ionic liquid, so resulting employable in WOLEDs and in LECs preparation. A rare example of LEC was prepared by Hashem Shahroosvand and coworkers in 2018 [ 122 ], based on a blend of the cationic complex [Ru(bpy) 3 ] 2+ and a neutral zinc (II) complex derived from diphenylcarbazone ligands. The crystal structure of the Zn fluorescent complex was examined, and the assignment of ground- and excited-state transitions was achieved by TD-DFT analysis.…”

Effect of Optical and Morphological Control of Single-Structured LEC Device

“…Adding a transport layer can reduce the loss of exciton by controlling the movement of the charge during the recombination of a charge that has been injected through the two electrodes. Moreover, a change in the synthesis ratio of the emission layer changes the number of ions produced, helping to transport charge, showing a tendency for LEC to increase its performance [ 4 , 5 , 6 , 7 , 8 ]. Among these studies, some researchers have reported on LEC devices based on iridium compounds or ruthenium compounds such as complex compounds that mix Ru(bpy) 3 2+ with 2,2′-bipyridyl ligands [ 9 , 10 ].…”