白光有机电致发光器件中Rubrene超薄层的发光性能

Luminescent Properties of White Organic Light-Emitting Devices Based on Rubrene Ultrathin Layer

以黄光荧光染料5,6,11,12-Tetraphenylnaphthacene(Rubrene)作为超薄层,制备了白光有机电致发光器件,并采用改变荧光超薄层厚度的方法,通过表征器件的电致发光光谱,分析了超薄层中染料浓度对器件性能的影响.研究结果表明,在荧光染料Rubrene的厚度为0.3 nm时,器件可以同时实现黄光和蓝光的等强度发射,从而得到性能优良的白光器件,最高亮度达到3700 cd/m2,颜色坐标为(0.32,0.33).器件中蓝光来自N,N′-Bis-(1-naphthyl)-N,N′-biphenyl-1,1′-biphenyl-4,4′-diamine(NPB)的电致发光,而器件优良的光电性能是由于Rubrene分子直接载流子陷阱(DCT)效应和NPB分子向Rubrene分子传递能量的协同作用所致.

The development of white organic light-emitting devices （WOLEDs） generated lots of interests in this area, as these devices can be employed not only as illumination fight source but also as backlight source candidate for next generation flat-panel displays. To achieve white emission from OLEDs, an additive mixture of three primary colors, i.e. , red, green, and blue （RGB） or a complementary color modification is indispensable. Comparing to the undoped device, the performances of doped red OLEDs and blue OLEDs were enhanced. Thereafter doping highly fluorescent dyes in emission layer became an important approach to realize WOLEDs with excellent performance. WOLEDs based on an uhrathin layer of yellow fluorescent dye 5,6,11, 12-tetraphenylnaphthacene（Rubrene） were investigated. By changing the thickness of ultrathin dye layer fabricated by thermal vacuum deposition and analyzing electroluminescent（EL） spectra of devices, concentration effect of dye on the performance of the devices was analyzed. The results showed that the balanced intensity of yellow and blue light for white light emission was obtained in the device when the thickness of fluorescent dye Rubrene was 0.3 nm. The blue light emitted from fluorescent material N, N＇-bis-（ 1-naphthyl ） -N, N＇-biphenyl-1,1 ＇-biphenyl-4,4＇-diamine（NPB） and the yellow light was from fluorescent Rubrene dye. A maximum luminance of 3700 cd/m2 was obtained. The Commissions International L＇Eclairage（CIE） coordinates located at（0.32, 0.33）, which is almost consistent with the optimum white CIE of （0. 333, 0. 333）. The high performance of WOLED was ascribed to direct carrier trapping（DCT） effect of Rubrene and efficient energy transfer from NPB to Rubrene.