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Transient thermal analysis of white organic light-emitting diode for heat-dissipation application

The thermal conductivity of the organic light-emitting material in a white organic light-emitting diode (WOLED) was precisely estimated by solving two-dimensional transient heat transfer equation and fitting experimental data. A WOLED usually operates in relatively high current mode to maintain higher brightness for lighting application. A practical solution for heat dissipation is crucial for properly applying WOLED in lighting application. Thermal conductivity of a material is a critical parameter for developing heat dissipation solution. A typical WOLED consists of several thin organic light-emitting layers with similar thermal characteristics sandwiched by anode and cathode. These organic layers can be regarded as a single organic light-emitting material for simplifying thermal analysis. The thermal characteristic of the organic light-emitting material can be represented by an effective or equivalent thermal conductivity in analytical model. The analytical model of temperature distribution was obtained from solving two-dimensional transient heat transfer equation with simplified bi-layer structure. The effective thermal conductivity of the thin-film organic light-emitting material can be precisely estimated by fitting analytical temperature distribution function to the experimental data. Our preliminary investigation indicates that the thermal conductivity of the organic light-emitting material is estimated between 0.28 and 0.29 w/m°C, similar to well-known organic compounds.