The Effect of the Interface Layer on the Electronic Parameters of the Light Emitting Electrochemical Cell (LEC) Device Based on Iridium (III) Complex that Calculated by Different Methods

Abstract

We report a calculation of the electronic parameters and some optical measurement results of a light-emitting electrochemical cell (LEC), one of the most basic forms of electroluminescent films by modifying 4-(4-methoxy-N-naphthalen-1-ylanilino) benzoic acid (MA) as hole injection layer doped with an emissive layer that is ionic transition metal complex (Ir[dF(CF3)ppy]2(dtbpy))PF6-(Ir-iTMC). The electronic parameters of LEC device were computed using three different methods; Cheung and Cheung’s, Conventional Schottky and Norde, to evaluate the ideality factor (n), the barrier height ( ϕ ) and the series resistance (Rs) of the LEC device. The formation on indium tin oxide (ITO) substrate was analyzed by Atomic Force Microscopy (AFM). The HOMO-LUMO energy level and electronic charge distribution of the MA molecule were computed theoretically using Chemissian software. The MA’s HOMO-LUMO energy level is determined to be EHOMO = −5.27 eV and ELUMO = −1.40 eV. The ITO surface has been modified with the Self-Assembled Monolayers (SAM) technique as an interlayer to improve the surface working function by simplifying hole injection from the ITO anode to the Hole Transport Layer (HTL) in the LEC. The Ir- iTMC complexes containing Π-conjugated bridging ligand shown better external quantum efficiency (EQE), reaching to 1.49%. The max luminance values of the bare-LEC and LEC-MA are measured as 145 cd m−2 and 1240 cd m−2, respectively.