Green OLED based on double metallic mirrors in microcavity structures and double light-emitting structure

Tao An; Junyu Wu; Peng Li; Sheng Yang; Zhiming Ding

doi:10.3969/j.issn.1003-501X.2017.03.012

Article navigation > Opto-Electronic Engineering > 2017 Vol. 44 > No. 3 > 356-361

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Tao An, Junyu Wu, Peng Li, et al. Green OLED based on double metallic mirrors in microcavity structures and double light-emitting structure[J]. Opto-Electronic Engineering, 2017, 44(3): 356-361. doi: 10.3969/j.issn.1003-501X.2017.03.012

Citation:

Tao An, Junyu Wu, Peng Li, et al. Green OLED based on double metallic mirrors in microcavity structures and double light-emitting structure[J]. Opto-Electronic Engineering, 2017, 44(3): 356-361. doi: 10.3969/j.issn.1003-501X.2017.03.012

Green OLED based on double metallic mirrors in microcavity structures and double light-emitting structure

Department of Electric Engineering, Xi'an University of Technology, Xi'an 710048, China

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Corresponding author: Tao An, E-mail: antao@xaut.edu.cn

Received Date 28 September 2016

Revised Date 19 December 2016

Published Date 15 March 2017

Abstract

Abstract

Green microcavity organic light-emitting diodes (OLEDs) are fabricated by using double metallic mirrors in microcavity structures and double light-emitting structures. The structure of the device consists of Al(15 nm)/MoO₃(4 nm)/2T-NATA(10 nm)/NPB(15 nm)/NPB:C545T(x%, 20 nm)/Alq3:C545T(4%, 20 nm)/Bphen(35 nm)/LiF(1 nm)/Al (200 nm), where x is the doping concentration. When the doping concentration is 3%, the device has the best photoelectric properties, which is named as device B₁.The reference device B₂ is prepared based on ITO, for the analysis of microcavity effect. B₁ and B₂ CIE are (0.2889, 0.620) and (0.3168, 0.5571), so the microcavity device could emit more green light. At 100 mA/cm², the brightness of devices B₁ and B₂ is 5076 cd/m² and 4818 cd/m², and the maximum brightness of the both devices are 9277.7 cd/m² and 10440 cd/m². At 100 mA/cm², luminance efficiency of devices B₁ and B₂ are 6.0 cd/A and 5.61 cd/A, and the luminance efficiency of the both devices are 8.6 cd/A and 7.97 cd/A. Compared with the reference devices, green microcavity device has a higher current efficiency and better color purity, which attributes to the microcavity effect.
- OLED /
- green microcavity device /
- double light-emitting layer structure /
- double metallic mirrors

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References

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Overview

Overview

Abstract:Organic light emitting devices (OLEDs) have some performances, such as low power consumption, ultra-light, fast response speed, high-definition, self-luminous and viewing angle, etc, which are expected to become a mainstream of the next generation of display devices. It is found that the microcavity structure can narrow the luminescence spectrum of the thin film and improve the luminescence color purity of the device effectively. We prepared a light-emitting device by using high vacuum deposition process and high-precision film thickness detector. This paper designed and prepared the green OLED devices based on double metallic mirrors in microcavity structures, of which the process was by vacuum evaporation and double metallic mirrors of devices: Al/MO₃ as device of anode and hole injection layer, and LiF/Al as device cathode and electron injection layers. Organic material C545T was as green microcavity device of light-emitting materials. The device structure is Al(20 nm)/MoO₃(4 nm)/2T-NATA(10 nm)/NPB(15 nm)/NPB:C545T(x%, 20 nm)/Alq3: C545T (4%, 20 nm)/Bphen (35 nm)/LiF(1 nm)/Al(200 nm), where x is the doping concentration, denoted as device B₁. In order to analyze the microcavity effect, another preparation was made based on the ITO reference device B₂. The microcavity effect of the device was analyzed by comparing the device's luminous brightness, luminous efficiency and luminescent color purity. The experimental results show that the device has the best optical and electrical properties when the doping concentration of device B₁ is 3%. We found B₁ and B₂ color coordinates, (0.289, 0.620) and (0.317, 0.557), respectively. It can be judged that the luminescent color of the microcavity device B¹ is purer. Then, microcavity device for microcavity effects could improve forward direction luminance intensity and luminance efficiency. At 100 mA/cm², the brightness of devices B₁ and B₂ are 5076 cd/m²and 4818 cd/m², and the maximum brightness of the both devices are 9277.7 cd/m² and 10440 cd/m². At 100 mA/cm², luminance efficiencies of devices B₁ and B₂ are 6.0 cd/A and 5.61 cd/A, and the maximum luminance efficiencies of the both devices were 8.6 cd/A and 7.97 cd/A. We can conclude that, compared with the reference device, the green microcavity device has better luminous efficiency and color purity than the reference device under the effect of the microcavity, and the photoelectric performance of the device is best when the C545T doping concentration is 3% and the thickness is 20 nm.