Electrothermal Simulation of Large-Area Semiconductor Devices

Christoph Kirsch ,Stéphane Altazin ,Roman Hiestand ,Ton Offermans ,Lieven Penninck ,R Ferrini ,Tilman Beierlein ,Beat Ruhstaller

doi:10.21152/1750-9548.11.2.127

Abstract

The lateral charge transport in thin-film semiconductor devices is affected by the sheet resistance of the various layers. This may lead to a non-uniform current distribution across a large-area device resulting in inhomogeneous luminance, for example, as observed in organic light-emitting diodes (Neyts et al., 2006). The resistive loss in electrical energy is converted into thermal energy via Joule heating, which results in a temperature increase inside the device. On the other hand, the charge transport properties of the device materials are also temperature-dependent, such that we are facing a two-way coupled electrothermal problem. It has been demonstrated that adding thermal effects to an electrical model significantly changes the results (Slawinski et al., 2011). We present a mathematical model for the steady-state distribution of the electric potential and of the temperature across one electrode of a large-area semiconductor device, as well as numerical solutions obtained using the finite element method.

Highlights

In a large-area semiconductor device, such as a solar cell or module, the electric charge generated inside the device due to light absorption needs to be transported towards the edges of the device in order to produce electric current
This may lead to a non-uniform current distribution across a large-area device resulting in inhomogeneous luminance, for example, as observed in organic light-emitting diodes (Neyts et al, 2006)
In a typical thin-film device this lateral charge transport is affected by the sheet resistance, which increases as the film thickness decreases

Summary

INTRODUCTION

In a large-area semiconductor device, such as a solar cell or module, the electric charge generated inside the device due to light absorption needs to be transported towards the edges of the device in order to produce electric current. In an organic light-emitting diode (OLED) device, for example, these are stacked emissive and conductive layers, which are placed between electrode layers (anode and cathode) The charge transport between the semiconductor stack and the top electrode (in fel ) This is usually described by temperature-dependent current-voltage characteristics, in which the current density in the semiconductor stack, js (ψ −ψ 0 ,T ) [Am−2 ] , is given as a function of the voltage across the stack (potential difference ψ −ψ 0 ). The complete coupled 1D-2D electrothermal model is discretized using the finite element method, as described

DISCRETIZATION AND SIMULATION RESULTS

Findings

CONCLUSIONS