Thermal analysis of high intensity organic light-emitting diodes based on a transmission matrix approach

Abstract

We use a general transmission matrix formalism to determine the thermal response of organic light-emitting diodes (OLEDs) under high currents normally encountered in ultra-bright illumination conditions. This approach, based on Laplace transforms, facilitates the calculation of transient coupled heat transfer in a multi-layer composite characteristic of OLEDs. Model calculations are compared with experimental data on 5 cm  5 cm green and red-emitting electrophosphorescent OLEDs under various current drive conditions. This model can be extended to study other complex optoelectronic structures under a wide variety of conditions that include heat removal via conduction, radiation, and convection. We apply the model to understand the effects of using high-thermalconductivity substrates, and the transient thermal response under pulsed-current operation.

Characterization, modeling, and analysis of organic light-emitting diodes with different structures

“…For a flat OLED package with a relatively large surface area, the bidirectional heat flow on both sides of the flat OLED package should be considered [31],[ [32]. There are two heat dissipation paths: one is downward through the organic layers to the substrate, and the other one is upward through the encapsulant to the packaging surface.…”

Analysis of negative capacitance and self-heating in organic semiconductor devices

“…1,2 23 Different remedies were taken to reduce the heat generation 24 on the anode caused by the resistive material. For example, 25 metal grids were added on top of the anode to decrease the 26 potential drop leading to more homogeneous potential, cur-27 rent, temperature, and light distributions. 3 However, in small 28 organic devices heat generation has only recently been of 29 concern.…”

Elucidation on Joule heating and its consequences on the performance of organic light emitting diodes

“…Further, to get a complete understanding of the thermal processes, we have calculated the heat generation inside OLEDs using theoretical formalism introduced by Qi and Forrest 15 based on transverse matrix approach for OLEDs. In this formalism, heat conduction equation was solved using Laplace transform method to study the combined effects of thermal radiation, conduction, and convection.…”

“…However, the effect of encapsulation on the internal heating of the device remained a topic to be considered for detailed study. Recently, Forrest et al 15 have proposed a transmission matrix analysis for the thermal studies of OLEDs. They have solved the heat conduction equations by Laplace transform method proposed by Pipe 22 to determine the synergy of thermal radiation, conduction, and convection and non-dissipative energy losses through OLED light emission.…”

“…It has been reported that 97%-99% of the supplied power is dissipated via the heat losses inside an OLED. 15 The internal Joule heating causes the exciton dissociation, which leads to the decrease in g ext . Nakanotani et al 16 have studied the effect of the cathode diameter and the conductivity of substrate on device performance.…”