基于微结构阵列基板的高效顶发射OLED器件

High-efficiency top-emitting OLEDs based on microstructure array substrate

为了提高顶发射OELD的效率,降低电压,基于纳秒激光刻蚀技术制备了一种用于顶发射OLED的低成本可重复的方形微结构阵列基板,在此基础上制备了顶发射OLED器件。实验发现,利用这种基板可以有效提高器件的出光效率,降低器件的驱动电压。其中,使用20μm的方格微结构阵列基板的器件的最高效率达到66.7cd/A,40mA/cm^2下亮度达到20 103cd/m^2,相比于未经刻蚀的无结构器件分别提高9.8%和6.9%;而使用40μm的方格微结构阵列基板的器件驱动电压最低,在40mA/cm^2下为9.58V,相较未经刻蚀的无结构器件降低了0.26V。分析表明,器件光效的提升和驱动电压的降低主要有两点原因:首先由于基于微结构阵列基板制备的器件中存在褶皱结构,可以破坏器件的光波导,并且增大了器件面积而降低驱动电压;其次纳秒激光刻蚀产生的光栅条纹可以提高光提取效率,同时增强局部电场以提高电极的载流子注入能力。

In order to improve the efficiency of the top emitting OELD and reduce the driving voltage,a low-cost reproducible square microstructure array substrate for top-emitting OLEDs was fabricated based on nanosecond laser etching technology.Based on this substrate,the green top-emitting OLED devices were fabricated.It is found that the microstructure array substrate can effectively improve the light extraction efficiency and reduce the driving voltage of the device.Among them,the maximum efficiency of the device using the 20μm square microstructure substrate is 66.7 cd/A and the brightness is 20 103 cd/m^2 at 40 mA/cm^2,which is 9.8%and 6.9%higher than that of the normal device,respectively.The device based on the 40μm square microstructure array substrate has the lowest driving voltage of 9.58 Vat 40 mA/cm^2,which is 0.26 Vlower than that of the normal device.The analysis shows that the improvement of the light efficiency of the device and the reduction of the driving voltage are mainly caused by two reasons.Firstly,due to the presence of the wrinkle structure in the device,the optical wave-guide mode of the device can be destroyed,and the device active area is increased to reduce the driving voltage.Secondly,the grating fringes made by the second nanosecond laser etching can improve the light extraction efficiency while enhancing the local electric field to improve the carrier injection capability of the electrode.