Improvement of Color Purity of Organic Monochromatic Green Top-emitting Micro-display Devices by Using Optical Microcavity
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摘要: 有机电致发光器件的发光颜色与色纯度在很大程度上受限于有机材料本身特性,而通过光学微腔效应可以从器件结构的改变来进行色纯度的调节。本文介绍了一种通过调节有机结构中空穴传输层和电子阻挡层厚度,从而改变器件微腔腔长,获得高纯度顶发射单色发光器件的方法。利用这种方法制作的有机顶发射绿色磷光器件结构为Si Substrate/Ag/ITO/ NPB: F16CuPc(10 nm, 3%)/NPB(x nm)/ TCTA(y nm)/ mCP: Ir(ppy)3(40 nm, 6%)/ Bphen: Liq(30 nm, 40%)/Mg: Ag(12 nm, 10%)/Alq3(35 nm),改变NPB和TCTA的厚度,获得了高色纯度发光器件,正向出射绿光的色坐标达到(0.2092,0.7167),接近标准绿光(0.21, 0.71)。Abstract: The color purity of organic light-emitting devices is restricted mostly by the intrinsic character of the emitting material; however, the optical microcavity can improve the color purity by changing the structure of the devices. In this study, we demonstrated that a high color purity monochromatic top-emitting device can be obtained by changing the length of the microcavity. By adjusting the thicknesses of the hole transport layer and electron barrier layer, high color purity organic green phosphorescent top-emitting electroluminescent devices were fabricated. The structure of the devices was an Si substrate/Ag/ITO/NPB: F16CuPc (10 nm, 3%)/NPB (x nm)/TCTA (y nm)/mCP: Ir(ppy)3 (40 nm, 6%)/Bphen: Liq (30 nm, 40%)/Mg: Ag (12 nm, 10%)/Alq3 (35 nm). Direct green emission with chromaticity coordinates of (0.2092, 0.7167) was obtained by changing the thicknesses of NPB and TCTA; this resulted in standard green light (0.21, 0.71).
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Key words:
- micro-OLED /
- green light /
- color purity /
- optical microcavity
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表 1 器件主要膜层及所用材料
Table 1. Layers and materials of device
Layer Material anode ITO HIL Copper(II)1, 2, 3, 4, 8, 9, 10, 11, 15, 16, 17, 18, 22, 23, 24, 25-hexadecafluoro-29H, 31H-phthalocyanine(F16CuPc)
N, N'-Di-[(1-naphthyl)-N, N'-diphenyl]-1, 1'-biphenyl)-4, 4'-diamine (NPB)HTL N, N'-Di-[(1-naphthyl)-N, N'-diphenyl]-1, 1'-biphenyl)-4, 4'-diamine (NPB) EBL 4, 4', 4''-tris(carbazol-9-yl)-triphenylamine (TCTA) EML 1, 3-bis(9-carbazolyl)benzene(mCP)
Iridium, tris[2-(2-pyridinyl-kN)phenyl-kC](Ir(ppy)3)ETL 4, 7-Diphenyl-1, 10-phenanthroline(Bphen)
8-hydroxyquinoline lithium(Liq)cathode Mg/Ag CPL 8-Hydroxyquinoline aluminum salt(Alq3) 表 2 不同腔长器件的光电特性
Table 2. Optoectronic performance of device with different cavity lengths
Device Luminance/(cd/m2) Current efficiency/(cd/A) Peak wavelength/nm FWHM/nm External quantum efficiency/% CIEx, y Color shift[CIE 1931] A 6330 33.80 524 73 9.19% (0.3713, 0.6019) (0.1613, 0.1081) B 7439 39.73 524 70 10.59% (0.3601, 0.6110) (0.1501, 0.0990) C 2198 11.74 524 84 3.39% (0.3959, 0.5821) (0.1859, 0.1279) D 9123 48.72 524 66 12.75% (0.3436, 0.6243) (0.1336, 0.0857) E 5477 29.25 520 33 7.67% (0.2092, 0.7167) (0.0008, 0.0067) 表 3 不同HTL & EBL厚度器件的光电特性
Table 3. Optoectronic performance of device with different HTL & EBL thickness
Device Luminance/(cd/m2) Current efficiency/(cd/A) Peak wavelength/nm FWHM/nm External quantum efficiency/% CIEx, y Color shift[CIE 1931] E 5477 29.25 520 33 7.67 (0.2092, 0.7167) (0.0008, 0.0067) E1 5261 28.09 520 32 7.58 (0.2079, 0.7173) (0.0021, 0.0073) -
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