缓冲层和掺杂的电子传输层对有机电致发光器件发光效率影响的研究

Influence of buffer layer and doped electron transport layer on the luminance efficiency of organic light-emitting diode

针对有机发光器件需要提高发光效率问题,利用其最高被占用分子轨道(HOMO)有利于改善空穴注入的特点,将氧化钼(MoO3)插入m-MTDATA与NPB之间;将羟基喹啉锂(Liq)掺入4,7-联苯-1,10-邻二氮杂菲(Bphen)作n型电子传输层,制备具有空穴缓冲层和n型掺杂电子传输层的有机电致发光器件。通过单载流子电子器件J-V曲线的比较,将掺杂质量分数确定为w(Bphen)∶w(Liq)=65∶35。在完整器件中,随着MoO3厚度的增加,器件效率改善显著,当MoO3厚度达到1nm时,器件性能最佳,此后趋于饱和,对厚度变化不敏感。说明使用MoO3及n型掺杂后空穴及电子的注入传输均获得明显提高,并在发光区域达到有效平衡,器件的亮度及发光效率获得明显改善,与控制器件相比,电流效率、功率效率及亮度分别提高约62%、约98%和约60%,电压V下降了约28%。

We fabricated an organic light emitting diode （OLED） with MoO3 inserting in m-MTDATA/NPB interface as hole injection buffer layer,incorporating an n-doping transport layer which comprises 8-hydroxy-quinolinato lithium （Liq） doped into 4,7-diphyenyl-1,10-phenanthroline （Bphen） aseolectron injection layer（ETL） By comparing the J-V curves of only devices,the doping rate was set as w（Bphen）∶w（Liq）=65∶35. The device performance was enhanced significantly after using Liq and MoO3. However,the performance was saturated when the thickness was over 1nm. In order to find the reason for improvement in performance,hole-only and electron-only devices were fabricated. It’s the use of MoO3 and n-doping in ETL that facilitated the hole injection and electron injection and transport respectively,reached effective carrier balance in emission zone and improved the device luminance efficiency greatly. The cur-rent efficiency,power efficiency and luminance of the devices were improved by about 62%,about 98% and about 60%,with the voltage reduced by about 28%.