加入激子阻挡层增强白色有机发光器件效率

Enhances to Efficiency of White Organic Light Emitting Diodes by Introducing an Exciton Block Layer

通过在发光层(EBL)与电子注入层之间增加激子阻挡层(EBL)制备了新型白色有机发光器件(WOLED)。有EBL的新型器件效率和亮度均比传统结构器件高50%,在电流密度为4 mA/cm2时效率达到3.42 cd/A,最大亮度为11 000 cd/m2(16 V),色坐标为x=0.34、y=0.36;而具有相同EBL厚度的传统结构器件,在电流密度为4 mA/cm2时效率为2.15 cd/A,最大亮度为6 259 cd/m2(16 V)。效率的提高是由于EBL的限制作用而提高了激子浓度。测量了器件的效率与电流密度关系,随电流密度增加电流效率的衰减缓慢,说明短寿命红色搀杂剂的激子-激子湮灭很弱。

A new white organic light emitting diode（WOLED） was constructed by sandwiching an exciton blocking layer（EBL） between the emitting layer（EML） and the electron-injection layer. The new device with exciton confined layer shows a 50% higher efficiency and luminance than that of the device with conventional structure . It has an efficiency of 3.42 cd/A at a current density 4 mA/cm^2 ,a maximum luminance of 11000 cd/m^2 at 16 V, and the ClE （Commission International de l＇ Eclairage） coordinates x = 0.34, y = 0.36, while for the device of conventional structure with the same EML thickness,the efficiency at a current density 4 mA/cm^2 is 2.15 cd/A,and its maximum luminance is 6 259 cd/m^2 （16 V）. The enhancement of efficiency is attributed to high density of exciton due to confinement of EBL. The dependences of efficiency on current density for both devices were examined. The slow decrease of efficiency with the increase of current density indicates weak exciton-exciton annihilation results from the florescence dye with a short lifetime.