利用亮度波形证明固态阴极射线发光

Proof of Solid State Cathodoluminescence by Using Brightness Waveform

制备了3种结构的器件:A:ITO/SiO2/Alq3/Al,B:ITO/Alq3/SiO2/Al,C:ITO/SiO2/Alq3/SiO2/Al。对于器件A和B,在正向偏压(ITO接正极)下才能观察到发光;而对于器件C,在正向和反向偏压下都可以观察到发光。随着电压升高,器件B和C产生的蓝色发光相对绿光逐渐增强。这主要是由于SiO2中的加速电子碰撞激发Alq3发光层产生热电子,并与空穴形成电子空穴对,复合产生蓝光;而对于器件A,在反向偏压下被热电子碰撞激发出的空穴与正向偏压下从Al电极进入的电子复合形成激子,产生绿色发光。这些结构的器件发光不但可来源于电子与积累的空穴复合,而且也来自固态阴极射线发光。

Three different inorganic-organic hetero-junctions （A ： ITO/SiO2/Alq3/Al, B ： ITO/Alq3/SiO2/Al and C： ITO/SiO2/Alq3 / SiO2/Al ） were fabricated. The emission can be observed only under positive bias in devices A and B, but under both biases in device C according to their brightness waveforms. With increasing voltage, the increase in blue emission in devices B and C is faster than that in green emission. This is because that the recombination of hot electrons and boles, i.e., electron-hole pairs, produced blue emission in devices B and C, and the recombination of electrons injected from AI with the accumulated holes, which are excited by hot electrons, produced green emission in device A. Hence, the emissions of the devices are attributed to not only the recombination of electrons and accumulated holes, but also the cathodoluminescence-like （CL-like） emission.