The Optical Effect Of Organic Light-emitting Devices And Optimization For Its Efficiency

Recently,organic light-emitting diodes(OLEDs) based on organic materials are one of the most promise technology for fiat-panel displays because of the characteristics of high efficiency,low voltage operation,wide-viewing angle,simple fabrication process,surface emitting-light,easily realizing of large-area,full-colour and flexibility displays.In theory,a "weak micro-cavity" optical model was used to describe the weak optical micro-cavity effect.Based on this model,we investigated the electroluminescent spectra.forward light intensities(spectrally integrated).total light intensities(spectrally and spatially integrated) distribution of radiative emission into external,substrate and ITO/organic mode.The performance of bi-layer organic light emitting diodes was investigated with different thickness of hole transport layer.It was found that the electroluminescence efficiency was improved 50%when the thickness of hole transport layer varied from 30 nm to 150 nm.The increasement of efficiency was attributed to the more electron-hole balance.These results are expected to give insight for improving the performances of device.