Analytical modelling and parameters extraction of multilayered OLED

Abstract

This research study investigates electrical performance of the multilayered organic light-emitting diode (OLED) with a focus on the role of charge injection, transport and emission layers. Device parameters; luminescence and current density are extracted using Silvaco ATLAS numerical device simulator and validated through the fabricated experimental results with a minor deviation of 3%. Furthermore, a mathematical model is applied to extract other device parameters such as electric field, charge carrier mobility, concentration and current density. Additionally, the multilayered device architecture is critically analysed through cut line methodology to better comprehend the internal device physics in terms of hole-electron mobility, concentration and their recombination. Subsequently, the performance parameters extracted using analytical model are compared with the results of internal analysis and a close match is observed. These results prove the Poole-Frenkel mobility-dependent behaviour in the OLEDs that varies following electric field. Analyses also highlight high electron and hole concentrations in the vicinity of the emission layer as a reason of high luminescence in the multilayered OLED, directly following the Langevin's theory of recombination in organic semiconductors. These analyses highlight the impact of different layers in the OLEDs and thus open up new horizons to further performance improvement in these devices.

Numerical modeling and parameters extraction of novel triple hole block layer‐based organic light‐emitting diode for display

“…[11][12][13] These have been successfully utilized by researchers for analyzing electric field 11 and internal parameters (charge carrier concentration, their mobility, and current density) of the OLED. For verifying the model, cut-line analysis of Device C was performed using Silvaco Atlas, 8 and the results of cut-line analysis and the model were compared. Before this, the analysis results of Device C were compared with the fabricated device 4 to overall validate the simulation results.…”

“…The same was observed for the multilayered OLED. 8 The main reason for this minor discrepancy in simulated and analytical values may be due to the slight variation in initial assumption of constants such as electron/hole concentration and acceptor/donor concentration.…”

“…Each of these layers was responsible for charge injection, and the device performance improved significantly with their addition. However, through internal cut‐line analysis and modeling, 8 it was observed that charge imbalance still exists within multilayered OLED. As a result, holes (being the faster moving charge carrier) crossed the emission layer (EML) to reach the cathode and did not take part in recombination 4 .…”

“…The HBL was placed next to the EML, thereby restricting the movement of holes. The high HOMO (highest occupied molecular orbital) level of the HBL blocks the holes, and judiciously selecting HBL material with a low LUMO (lowest unoccupied molecular orbital) level enhanced the electron injection 8 within the device. Thus, a balanced charge carrier concentration was achieved resulting in augmented OLED performance.…”

“…The complete article is divided into five sections starting with this introduction in Section 1. This is followed by Section 2, wherein a brief background information of previous work 8 related to modeling of internal parameters of multilayered OLED (electric field, charge carrier mobility, carrier concentration, and current density) is discussed. Thereafter, the model is utilized for novel triple block layer OLED, and its results are discussed in Sections 3 and 4, respectively.…”