Interface electronic structures of organic light-emitting diodes with WO3 interlayer: A study by photoelectron spectroscopy
Interface electronic structures of organic light-emitting diodes with WO3 interlayer: A study by photoelectron spectroscopy
复制标题
DOI：
10.1016/j.orgel.2009.02.017
复制
发表时间：
2009-07
影响因子：
3.2
通讯作者：
M. Son;Sehun Kim;Soonnam Kwon;Jeong Won Kim
中科院分区：
文献类型：
--
作者：
M. Son;Sehun Kim;Soonnam Kwon;Jeong Won Kim
用原位X射线和紫外光电子能谱研究了有机电致发光二极管(OLED)结构中空穴注入层和传输层界面的能级排列和化学反应。N，N‘-双(1-萘基)-N，N’-二苯基-1，1‘-联苯-4，4’-二胺(NPB)/氧化铟锡(ITO)的空穴注入势垒(HOMO)为1.32 eV，而在NPB和ITO之间插入一层WO_3层的空穴注入势垒显著降低到0.46 eV。势垒高度降低之后，功函数发生了很大的变化，这可能是由于形成了新的界面偶极子。在350℃热处理后，空穴注入势垒高度的降低基本消失。这归因于WO_3中发生的化学修饰，如氧空位的形成。
The energy level alignment and chemical reaction at the interface between the hole injection and transport layers in an organic light-emitting diode (OLED) structure has been studied using in-situ X-ray and ultraviolet photoelectron spectroscopy. The hole injection barrier measured by the positions of the highest occupied molecular orbital (HOMO) for N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB)/indium tin oxide (ITO) was estimated 1.32eV, while that with a thin WO3layer inserted between the NPB and ITO was significantly lowered to 0.46eV. This barrier height reduction is followed by a large work function change which is likely due to the formation of new interface dipole. Upon annealing the WO3interlayer at 350°C, the reduction of hole injection barrier height largely disappears. This is attributed to a chemical modification occurring in the WO3such as oxygen vacancy formation.