摘要
White color emitting organic electroluminescence (EL) device is a convenient means to realize full-color display because the three necessary primary colors could be obtained by color filters from white back light. In this paper a new three-layer device is presented. We used N, N′-bis-(lnaphhyl)-N , N′-diphenyl-1, 1′-biphenyl-4, 4′-diamine (NPB) as the hole transport layer, Alq as the electron transport layer, CuPc as the buffer layer, and TPBi as the blocking layer inserted between NPB and Alq.The 5,6,11,12-tetraphenyltetracene (Rubrene) as dopant was doped into the blocking layer.\;It was thought initially that if energy transfer existed between the host and dopant in photoluminescence (PL) of NPB doped with Rubrene, white emission might be obtained in a device such as ITO/CuPc/NPB:Rubrene/TPBi/Alq/Mg:Ag. Thus the PL of NPB:Rubrene system excited by NPB absorption band with different dopant concentrations were investigated in advance. There are two bands in the PL spectra, the blue one is emitted by NPB and the yellow one is by Rubrene. The ratio of these two bands can be adjusted by changing the Rubrene concentration. This shows that energy transfer does occur from NPB to Rubrene. Time-resolved spectra of this system, which will be given in another paper, confirm further that the energy transfer exists and is quite effective. White emission can be produced by adjusting the concentration of Rubrene in PL. However, devices of structure ITO/CuPc/NPB:Rubrene/TPBi/Alq/Mg:Ag were made according to these results with TPBi as the blocking layer, white emission can not be obtained by changing the Rubrene concentration.\;For another device of structure ITO/CuPc/NPB/TPBi:Rubrene/Alq/Mg : Ag, with a blocking layer TPBi doped by Rubrene concentration 1.5% inserted between NPB and Alq, white emission can be obtained. The highest luminance and maximum efficiency are 8635cd/m 2 and 1.39lm/W respectively , CIE coordinate x =0.31, y =0.32. The color of the emitted light can still be optimized by adjusting the relative thickness of the relevant layers and dopant concentration.\;The electroluminescence mechanism of two kinds of cells was discussed.
White color emitting organic electroluminescence (EL) device is a convenient means to realize full-color display because the three necessary primary colors could be obtained by color filters from white back light. In this paper a new three-layer device is presented. We used N, N′-bis-(lnaphhyl)-N , N′-diphenyl-1, 1′-biphenyl-4, 4′-diamine (NPB) as the hole transport layer, Alq as the electron transport layer, CuPc as the buffer layer, and TPBi as the blocking layer inserted between NPB and Alq.The 5,6,11,12-tetraphenyltetracene (Rubrene) as dopant was doped into the blocking layer.\;It was thought initially that if energy transfer existed between the host and dopant in photoluminescence (PL) of NPB doped with Rubrene, white emission might be obtained in a device such as ITO/CuPc/NPB:Rubrene/TPBi/Alq/Mg:Ag. Thus the PL of NPB:Rubrene system excited by NPB absorption band with different dopant concentrations were investigated in advance. There are two bands in the PL spectra, the blue one is emitted by NPB and the yellow one is by Rubrene. The ratio of these two bands can be adjusted by changing the Rubrene concentration. This shows that energy transfer does occur from NPB to Rubrene. Time-resolved spectra of this system, which will be given in another paper, confirm further that the energy transfer exists and is quite effective. White emission can be produced by adjusting the concentration of Rubrene in PL. However, devices of structure ITO/CuPc/NPB:Rubrene/TPBi/Alq/Mg:Ag were made according to these results with TPBi as the blocking layer, white emission can not be obtained by changing the Rubrene concentration.\;For another device of structure ITO/CuPc/NPB/TPBi:Rubrene/Alq/Mg : Ag, with a blocking layer TPBi doped by Rubrene concentration 1.5% inserted between NPB and Alq, white emission can be obtained. The highest luminance and maximum efficiency are 8635cd/m 2 and 1.39lm/W respectively , CIE coordinate x =0.31, y =0.32. The color of the emitted light can still be optimized by adjusting the relative thickness of the relevant layers and dopant concentration.\;The electroluminescence mechanism of two kinds of cells was discussed.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2000年第1期74-77,共4页
Chinese Journal of Luminescence
基金
国家自然科学基金!重大项目 ( 5 9790 0 5 0 )
国家自然科学基金项目!( 696870 0 2 )
上海市教委资助
关键词
白色显示
有机薄膜
电致发光器件
white displays
organic thin film
electroluminescent devices
