BCP在多层有机电致发光器件中的作用

作为空穴阻挡材料，BCP通常被用在蓝光以及白光有机电致发光器件中，其空穴阻挡能力随着其厚度的增加而增强；另一方面，在电场作用下，空穴也能隧穿厚度较薄的BCP层。为了深入了解BCP在多层有机电致发光器件中的作用，文章研究了不同电压下BCP层厚度对器件ITO/NPB/BCP/Alq₃∶DCJTB/Alq₃/Al电致发光光谱的影响。实验发现，较薄的BCP层可以部分地阻挡空穴并能调节能量在不同发光层之间的传递，从而容易获得白光器件；但该种结构器件的电致发光光谱随着电压的变化变动较大。当BCP层足够厚时，器件的电致发光光谱也变得相对较稳定； 当BCP的厚度为15 nm以上时，空穴就很难再隧穿过去。文章还讨论了不同电压下多层器件的电致发光光谱发生变化的原因。

The Role of BCP in Electroluminescence of Multilayer Organic Light-Emitting Devices

As a hole-blocking layer, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) is usually used in blue and white light electroluminescent devices. The ability of blocking holes of BCP layer depends on its thickness, and basically holes can tunnel through thin BCP layer. In order to know the role of BCP layer in electroluminescence (EL) of multilayer organic light-emitting diodes (OLEDs), in the present paper, the authors designed a multilayer OLED ITO/NPB/BCP/Alq₃∶DCJTB/Alq₃/Al and investigated the influence of thickness of BCP on the EL spectra of multilayer OLEDs at different applied voltages. The experimental data show that thin BCP layer can block holes partially and tune the energy transfer between different emissive layers, and in this way, it is easy to obtain white emission, but its EL spectra will change with the applied voltages. The EL spectra of multilayer device will remain relatively stable when BCP layer is thick enough, and the holes can hardly tunnel through when the thickness of BCP layer is more than 15 nm. Furthermore, the stability of EL spectra of the multilayer OLED at different applied voltages was discussed.