Systematic kMC Study of Doped Hole Injection Layers in Organic Electronics

Abstract

Organic light emitting diodes (OLED) play an important role in commercial displays and are promising candidates for energy-efficient lighting applications. Although they have been continuously developed since their discovery in 1987, some unresolved challenges remain. The performance of OLEDs is determined by a multifaceted interplay of materials and device architectures. A commonly used technique to overcome the charge injection barrier from the electrodes to the organic layers, are doped injection layers. The optimization of doped injection layers is critical for high-efficiency OLED devices, but has been driven mainly by chemical intuition and experimental experience, slowing down the progress in this field. Therefore, computer-aided methods for material and device modeling are promising tools to accelerate the device development process. In this work, we studied the effect of doped hole injection layers on the injection barrier in dependence on material and layer properties by using a parametric kinetic Monte Carlo model. We were able to quantitatively elucidate the influence of doping concentration, material properties, and layer thickness on the injection barrier and device conductivity, leading to the conclusion that our kMC model is suitable for virtual device design.

28‐1: Invited Paper: Bottom‐Up OLED Development by Virtual Design: Systematic Elimination of Performance Bottlenecks Using a Microscopic Simulation Approach

“…The resulting all-particle trajectories allow a detailed analysis of spatially resolved and material specific distributions of loss processes, as well as their dependency on material properties. (15,26,27,34). Details of the approach can be found in the references accordingly.…”

The Optimization of Hole Injection Layer in Organic Light-Emitting Diodes

“…To overcome the obstacles like limited charge carrier concentration or insufficient charge balance in the device due to large hole injection barriers, doping HILs is a proven technique [ 51 ]. Doped materials can be roughly classified into three categories: polymer materials, transition metal oxide materials, metal and metal compound materials.…”

Schottky-Contact Formation between Metal Electrodes and Molecularly Doped Disordered Organic Semiconductors

“…Currently, the models in the literature describing the doping physics for disordered organic semiconductors focus mostly on charge-neutral systems [8][9][10][11][12][13][14]. Experimentally, it has been shown that the charge-carrier mobility in homogeneous disordered organic semiconductors depends on the temperature, the electric field, and the charge-carrier concentration [15][16][17].…”

“…Based on these results, three-dimensional (3D) discrete lattice models with a Gaussian density of states (DOS) and threedimensional kinetic Monte Carlo (3D-KMC) simulation techniques of localized charge-carrier dynamics were developed [21][22][23][24][25][26]. These models can successfully explain measured electrical characteristics of OLEDs and have recently been applied to study the physics of molecularly doped systems [9][10][11][12][13][14]. From these simulation studies, it was found that a released charge carrier is not completely free to move, but stays at a nearby host molecule.…”