Transient response of organic light-emitting devices: A Monte Carlo simulation study

Abstract

A Monte Carlo simulation method has been conducted to study transient response of electroluminescence in single-layer light-emitting devices. The results from the numerical method have been compared with our recent (transient) experimental results. The simulation results supported the role and contribution of accumulated charges at the metal–semiconductor interfaces in device operation. Several parameters like barrier heights and mobilities of charge carriers, width and distribution of the accumulated space charge regions in the device, have been used in the simulation work. Additionally, barriers for charge injection have been considered to be modified by the presence of space charges near the injecting interfaces. A recipe has been established to estimate different parameters of device operation from the comparison between simulation and experimental results.

Electrical transport modelling in organic electroluminescent devices

“…After some time the signal then decays exponentially to a steady-state level. A Monte Carlo simulation scheme has been developed [80] to account for the shape of such signals, and to examine the impact of the various parameters which characterize the system. The physical situation under study commences with the bipolar injection of carriers through electrodes with particular barrier heights, under the application of an external electric field.…”

Monte Carlo simulation of organic light-emitting devices under alternating applied field

“…11 In the present work, we have extended the simulation procedure to incorporate sinusoidal applied voltage. A device was represented by a cubic lattice of N x ϫN y ϫN z sites.…”

“…The movement of a carrier has been explained in an earlier communication. 11 An exciton has been allowed to form only when an electron and a hole are located at nearestneighbor sites. We have neglected any role of exciton diffusion length in the simulation, which is low anyway in organic materials and, hence, did not allow any exciton to dissociate further into charge carriers.…”

“…2,3 To quantitatively describe the EL output and device current, numerical methods have recently been applied in LEDs. [6][7][8][9][10][11] The simulation studies, however, remained restricted, in general, to dc mode of operation and have recently been extended to transient cases. 10,11 In this article, we aimed to simulate EL under ac voltage.…”

Device optimization and transient electroluminescence studies of organic light emitting devices

“…Charge accumulation at HTL/ETL interface. of energy barriers, the significant differences between the mobilities in the different layers leads to the presence of mobility barriers at the internal interface, which, in turn, can be another source of interfacial space-charge formation.Theoretical simulations also support the contribution of the accumulated charges at the metal-semiconductor interfaces in device operation 62. Carrier transit versus carrier accumulation induced time delayTo summarize foregoing treatment, there are two possible mechanisms to explain the initial time delay of the transient electroluminescence: (i) finite charge carrier mobility and (ii) charge accumulation at the interface.…”