Impact of ZnO Nanoparticle Concentration on Charge Transport and Luminance Performance of Alq3–OLEDs: A Numerical Analysis

In this paper, a numerical investigation of an organic light-emitting diode (OLED) based on a bilayer architecture is presented, with particular emphasis on the influence of ZnO nanoparticles (ZNPs) concentration on charge transport, recombination dynamics, exciton formation, and luminescence performance. The studied device consists of a hole injection layer combined with an electron transport and emissive layer based on Alq3 doped with ZNPs. The impact of ZNPs concentration has been explicitly investigated with respect to carrier mobility, dielectric permittivity, Langevin recombination rate, and radiative exciton decay. The simulation results show that increasing ZNPs concentrations enhances charge balance, recombination efficiency, exciton density, and luminescence power. Furthermore, the variation in the ZNPs concentration, from 0% to 10% in the Alq3 layer, increases the electron charge density from 1.00 × 1015 cm−3 to 1.81 × 1015 cm−3, the recombination rate from 2.48 × 1020 cm−3 s−1 to 6.10 × 1020 cm−3 s−1, the exciton density from 0.16 × 1015 cm−3 to 0.42 × 1015 cm−3, and the power of luminescence from 0.23 W/μm2 to 0.45 W/μm2. The performance of Alq3–ZNPs–OLED is tenfold higher than that of pure Alq3–OLED. These findings demonstrate that the incorporation of ZNPs is a key parameter for ameliorating and optimizing OLED performance, which can serve various optoelectronic designs.