The Effects Of Micro-structure On The OLED Light Extraction Efficiency

The organic light emitting diode (organic light emitting diode, OLEDs) as the21st century a new type of flat panel display products, it has a self-luminous, wide angle, short reaction time, high luminous efficiency, wide color gamut, low operating voltage, thin panel, can be made large advantages of size and deflection of the panel and simple process. As the technology matures thrive, high luminous efficiency of OLED is relative to other light-emitting display products, but due to its internal and external existence of waveguides and total internal reflection effect, its luminous efficiency is indeed relatively low. To this end, we have adopted the OLED structure layer within a variety of changes to improve the optical efficiency of the OLED.In recent years, people have been considering OLED structure layer etching grating structure can improve the optical efficiency of the OLED, but essentially the grating structure itself can not bring the improvement of the OLED light extraction efficiency. When OLED structure layer etched a two-dimensional periodic structure-grating, with using Gsolver to simulate the effect of different grating parameters on the light extraction efficiency of OLED, we found that the light extraction efficiency of the structure of the OLED layer with the etched grating structure did not change, which indicates that the diffraction characteristics of the grating structure, the grating phase modulation of light waves is not the root to improve the OLED light extraction efficiency. In practice, etched the grating structure in the OLED structure improving the light efficiency is likely due to the effect of micro-structure.To this end, we specialize in the light extraction efficiency when adding a micro-structure within the layers of the OLED structure(1) We selected in the OLED waveguide effect layer interface to plus micro structure using LightTools to simulate the calculation of various parameters of micro-structure of the OLED light extraction efficiency. From the calculation, we found that the micro-structure can undermine the ripple effect, bringing the light source light efficiency (nearly4times), micro-structure can also be applied to the OLED structure, improve the OLED light efficiency. (2) In addition to micro-structure, we study the effect on the light extraction efficiency of OLED when pulsing low refractive index grids in the internal structure layer in OLED (that is, between the organic layer and the ITO layer). LightTools software simulation calculations to the optical efficiency of the OLED under different grid parameters, from the calculated results, we can find such a low refractive index of the grid can effectively improve the light extraction efficiency of OLED. In the OLED under certain parameters, to increase nearly doubled the optical efficiency of the OLED.