PVK空穴传输层对有机电致发光器件性能的影响

Influence of PVK Hole Transport Layer on Performance of Organic Electroluminescent Devices

以聚乙烯基咔唑poly(N-vinylcarbazole)(PVK)旋涂层为空穴传输层,着重研究了PVK层厚度对双层器件氧化铟锡(ITO)/PVK/tris-(8-hydroxyquinoline)aluminum(Alq3)/Mg∶Ag/Al器件性能的影响。测试结果表明,当Alq3层厚度一定时(50nm),只有PVK层为适当厚度(18nm)时双层器件才有最优良的器件性能,即最低的起亮电压,最高的发光亮度和效率。同时对比了不同PVK层厚度的PVK/Alq3双层器件之间以及PVK/Alq3与N,N′-bis-(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine(NPB)/Alq3双层器件寿命的差异。测试结果表明,尽管越厚的PVK层对应的PVK/Alq3双层器件发光性能并不是越好,但器件寿命越长。原因是器件Alq3层内形成的Alq3+越少,因此器件稳定性越好;而PVK/Alq3与NPB/Alq3双层器件寿命的差异来自不同空穴传输层的制备工艺和能级结构的不同。

With poly（N-vinylcarbazole） （PVK） layer used as hole transport layer （HTL）, influence of thickness of PVK layer on indium tin oxide（ITO）/PVK/tris-（8-hydroxyquinoline） aluminum（ Alq3 ） /Mg： Ag/Al double-layer （DL） device＇s performance was investigated. Measurements showed that when the thickness of Alq3 was fixed to be 50 nm, the device with 18 nm PVK HTL has the best performance of light emission, e.g. , the lowest turn-on voltage, the highest brightness and efficiency. Differences between these PVK DL devices and N, N ＇-his- （ 1 -naphthyl ） -N, N＇-diphenyl- （ 1,1 ＇-biphenyl ） -4,4＇-diamine （ NPB ）/Alq3 DL devices＇ lifetime were compared. Results showed that the device with thickest PVK layer has the longest lifetime. The different lifetime between PVK and NPB DL device originated from the differences between fabrication techniques and energy band structure of the two HTLs.