摘要
为了研究有机电致发光器件(OLED)在高亮度下存在的电流下降现象,在不同强度的荧光激发下观察了单层和双层器件的电流密度(J-V)特性和电致(EL)光谱。在单层器件中发现,随着激发光的增强,发生了电流密度下降以及光谱蓝移现象,这是因为在低迁移率的有机物中,过剩的阴离子基对光子的强烈吸收,从而导致了载流子浓度的降低。在单层器件中插入4个不同厚度的空穴传输材料组成双层器件以平衡过剩的阴离子基,结果发现,随着厚度的增加电流密度下降和光谱蓝移的程度减少,当厚度超过50nm后,这种减少的程度变化不大。研究表明,插入适当厚度的空穴传输层能够抑制器件中的电流下降现象。
In order to study the current roll-off in organic light-emitting diodes(OLEDs) under high luminance,the current density versus voltage (J-V)characteristics and the spectra of single-layer and bilayer devices pumped by sources in varied radiation intensities have been observed.The current densities in single-layer device decrease and the spectra shifte towards blue region,since the large amounts of excess anion radicals intensely Absorb the emitted photons to cause the carrier density reduction. In order to balance the excess anion radicals,bilayer devices are constructed by inserting hole transport layers(HTLs) of four thicknesses in single-layer device.The current roll-off and spectral blue shift are reduced with the increase of the HTL thickness and decrease slightly when the thickness exceeds 50 nm.It is shown that inserting a hole transport layer of proper thickness is one of the methods to restrain the current roll-off.
出处
《光电子．激光》
EI
CAS
CSCD
北大核心
2009年第7期877-881,共5页
Journal of Optoelectronics·Laser
基金
上海市教委资助项目(2006AZ010)
上海大学创新基金资助项目(A10-0109-07-014)
上海市教育委员会科研创新重点资助项目(08ZZ42)
上海市引进技术的吸收与创新年度计划资助项目(06XX-28)
关键词
有机电致发光器件(OLED)
电流下降
光致激励
光谱蓝移
organic light-emitting diodes(OLED)
current decline in
photoluminescence pumping
spectral blue shift
