微腔有机电致发光器件的角度依赖性

Angle Dependence of Microcavity Organic Light-emitting Device

设计并制作了两个器件,一个是微腔有机电致发光器件(MOLED):G/DBR/ITO/NPB(46nm)/DPVBi(20nm)/Alq3(56nm)/LiF(1nm)/Al(150nm);一个是无腔器件(OLED):G/ITO/NPB(46nm)/DPVBi(20nm)/Alq3(56nm)/LiF(1nm)/Al(150nm)。测试并分析了器件性能。OLED在电流密度30mA/cm2时的电致发光(EL)光谱随观测角度由0°～70°都是一宽谱带,是发光层DPVBi的特征发光谱,峰值都在452nm处,半峰全宽均为70nm,色坐标均为(x=0.18,y=0.19),无腔器件没有角度依赖性。相同电流密度下,微腔器件的EL谱随观测角度由0°～70°,发光峰值蓝移,由472nm逐渐移至428nm;峰值相对强度渐弱,由0.32变至0.02;半峰全宽由14nm增加至120nm;色坐标由(x=0.14,y=0.10)变至(x=0.19,y=0.25),颜色由紫蓝变成蓝白到接近白色。微腔器件具有明显的角度依赖性。

We designed and made two devices, one is microcavity organic light-emitting device （MOLED）, and the other is non-microcavity device （OLED）. The structures of MOLED is G/DBR/ITO/NPB （46 nm）/ DPVBi （20 nm）/Alq3（56 nm）/LiF （1 nm）/Al （150 nm）; OLED is G/ITO/NPB （46 nm）/DPVBi（20 nm）/Alq3 （ 56 nm）/LiF （ 1 nm）/Al （ 150 nm）. The performances of MOLED and OLED were tested and analyzed. The OLED＇s electroluminescent （EL）-angle curve, at 30 mA/cm2 and changing the angle from 0° to 70°, is a broad spectrum. It is the characteristic spectrum of DPVBi luminescence layer, which peaked at 452 nm, the full width at half maximum （FWHM） is 70 nm. The color coordinates （CIE） are （x =0.18, y = 0.19）. It was proved that OLED has no angle dependence. The MOLED EL-angle curve at the same current of 30 mA/cm^2 is a narrow spectrum. We can see that, along with the detecting angle changing from 0° to 70°, the EL peak values decreases from 472 nm to 428 nm, namely blue shift. The peak intensity also decreased. The FWHM became larger from 14 nm to 120 nm. The CIE coordinates change from （x =0.14, y =0.10） to （y =0.19, 0.25）, the color changes into blue-white from purple-orchid. All of the above proved that the MOLED obviously has angle dependence. The angle dependence of MOLED is disadvantage for fiat display application, thus we need reduce it. But this characteristics is virtue and necessary for organic microcavity laser.