Random organic nano-textured microstructures formed by photoexcitation for light extraction of blue OLEDs

Yoonjay Han; Chang Ki Moon; Kwan Kim; Heon Lee; Jang Joo Kim

doi:10.1016/j.orgel.2020.105892

Random organic nano-textured microstructures formed by photoexcitation for light extraction of blue OLEDs

Yoonjay Han, Chang Ki Moon, Kwan Kim, Heon Lee, Jang Joo Kim

Research output: Contribution to journal › Article › peer-review

15 Citations (Scopus)

Abstract

Organic light-emitting diodes require efficient and inexpensive light extraction methods for applications toward lighting and displays. Here, a facile and effective method for fabricating random organic microstructures for efficient light extraction from blue OLEDs is presented. Simple drop casting of a TCTA and B4PyMPM mixed solution followed by UV curing results in films with irregular-shaped microstructures (DACMs), ideal for light extraction without diffraction patterns. An external quantum efficiency (EQE) of 44.3% is realized by attaching DACMs formed on a polymer film to a blue phosphorescent OLED. The efficiency is improved by 35% compared to a planar device without the light extraction layer, greater than the 22% improvement obtained by using hemispherical-shaped microlens arrays. The method is useful for OLED lighting and potentially in displays because of the simple fabrication method that is applicable to a large area on rigid or flexible substrates, the low material cost, the insolubility of the microstructure in alkyl halide solvents such as chloroform, and the controllability of the structure through the solution process. Furthermore, we fully discuss on the EQE, enhancement ratio and the efficiency of light extraction structure (ELOS). We show that enhancement ratio and ELOS should be obtained using the optimized device structure as the reference device to be useful indicators for the effectiveness of a light extraction structure.

Original language	English
Article number	105892
Journal	Organic Electronics
Volume	87
DOIs	https://doi.org/10.1016/j.orgel.2020.105892
Publication status	Published - 2020 Dec

Bibliographical note

Funding Information:
The authors thank Prof. Yun-Hi Kim and Soon-Ki Kwon in Gyungsang National University for the helpful scientific discussion especially on the reaction scheme of the materials. This work was supported by Industrial Strategic Technology Development Program ( 1007967 1) funded by the Ministry of Trade, Industry, & Energy (MOTIE, Korea) .

Publisher Copyright:
© 2020 Elsevier B.V.

Keywords

Efficiency of out-coupling structures
External light extraction layer
Nano-textured microstructures
Organic light-emitting diodes
Photoinduced charge transfer

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Biomaterials
General Chemistry
Condensed Matter Physics
Materials Chemistry
Electrical and Electronic Engineering

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10.1016/j.orgel.2020.105892

Cite this

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title = "Random organic nano-textured microstructures formed by photoexcitation for light extraction of blue OLEDs",

abstract = "Organic light-emitting diodes require efficient and inexpensive light extraction methods for applications toward lighting and displays. Here, a facile and effective method for fabricating random organic microstructures for efficient light extraction from blue OLEDs is presented. Simple drop casting of a TCTA and B4PyMPM mixed solution followed by UV curing results in films with irregular-shaped microstructures (DACMs), ideal for light extraction without diffraction patterns. An external quantum efficiency (EQE) of 44.3% is realized by attaching DACMs formed on a polymer film to a blue phosphorescent OLED. The efficiency is improved by 35% compared to a planar device without the light extraction layer, greater than the 22% improvement obtained by using hemispherical-shaped microlens arrays. The method is useful for OLED lighting and potentially in displays because of the simple fabrication method that is applicable to a large area on rigid or flexible substrates, the low material cost, the insolubility of the microstructure in alkyl halide solvents such as chloroform, and the controllability of the structure through the solution process. Furthermore, we fully discuss on the EQE, enhancement ratio and the efficiency of light extraction structure (ELOS). We show that enhancement ratio and ELOS should be obtained using the optimized device structure as the reference device to be useful indicators for the effectiveness of a light extraction structure.",

keywords = "Efficiency of out-coupling structures, External light extraction layer, Nano-textured microstructures, Organic light-emitting diodes, Photoinduced charge transfer",

author = "Yoonjay Han and Moon, {Chang Ki} and Kwan Kim and Heon Lee and Kim, {Jang Joo}",

note = "Funding Information: The authors thank Prof. Yun-Hi Kim and Soon-Ki Kwon in Gyungsang National University for the helpful scientific discussion especially on the reaction scheme of the materials. This work was supported by Industrial Strategic Technology Development Program ( 1007967 1) funded by the Ministry of Trade, Industry, & Energy (MOTIE, Korea) . Publisher Copyright: {\textcopyright} 2020 Elsevier B.V.",

year = "2020",

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doi = "10.1016/j.orgel.2020.105892",

language = "English",

volume = "87",

journal = "Organic Electronics",

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AU - Han, Yoonjay

AU - Moon, Chang Ki

AU - Kim, Kwan

AU - Lee, Heon

AU - Kim, Jang Joo

N1 - Funding Information: The authors thank Prof. Yun-Hi Kim and Soon-Ki Kwon in Gyungsang National University for the helpful scientific discussion especially on the reaction scheme of the materials. This work was supported by Industrial Strategic Technology Development Program ( 1007967 1) funded by the Ministry of Trade, Industry, & Energy (MOTIE, Korea) . Publisher Copyright: © 2020 Elsevier B.V.

PY - 2020/12

Y1 - 2020/12

N2 - Organic light-emitting diodes require efficient and inexpensive light extraction methods for applications toward lighting and displays. Here, a facile and effective method for fabricating random organic microstructures for efficient light extraction from blue OLEDs is presented. Simple drop casting of a TCTA and B4PyMPM mixed solution followed by UV curing results in films with irregular-shaped microstructures (DACMs), ideal for light extraction without diffraction patterns. An external quantum efficiency (EQE) of 44.3% is realized by attaching DACMs formed on a polymer film to a blue phosphorescent OLED. The efficiency is improved by 35% compared to a planar device without the light extraction layer, greater than the 22% improvement obtained by using hemispherical-shaped microlens arrays. The method is useful for OLED lighting and potentially in displays because of the simple fabrication method that is applicable to a large area on rigid or flexible substrates, the low material cost, the insolubility of the microstructure in alkyl halide solvents such as chloroform, and the controllability of the structure through the solution process. Furthermore, we fully discuss on the EQE, enhancement ratio and the efficiency of light extraction structure (ELOS). We show that enhancement ratio and ELOS should be obtained using the optimized device structure as the reference device to be useful indicators for the effectiveness of a light extraction structure.

AB - Organic light-emitting diodes require efficient and inexpensive light extraction methods for applications toward lighting and displays. Here, a facile and effective method for fabricating random organic microstructures for efficient light extraction from blue OLEDs is presented. Simple drop casting of a TCTA and B4PyMPM mixed solution followed by UV curing results in films with irregular-shaped microstructures (DACMs), ideal for light extraction without diffraction patterns. An external quantum efficiency (EQE) of 44.3% is realized by attaching DACMs formed on a polymer film to a blue phosphorescent OLED. The efficiency is improved by 35% compared to a planar device without the light extraction layer, greater than the 22% improvement obtained by using hemispherical-shaped microlens arrays. The method is useful for OLED lighting and potentially in displays because of the simple fabrication method that is applicable to a large area on rigid or flexible substrates, the low material cost, the insolubility of the microstructure in alkyl halide solvents such as chloroform, and the controllability of the structure through the solution process. Furthermore, we fully discuss on the EQE, enhancement ratio and the efficiency of light extraction structure (ELOS). We show that enhancement ratio and ELOS should be obtained using the optimized device structure as the reference device to be useful indicators for the effectiveness of a light extraction structure.

KW - Efficiency of out-coupling structures

KW - External light extraction layer

KW - Nano-textured microstructures

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KW - Photoinduced charge transfer

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Random organic nano-textured microstructures formed by photoexcitation for light extraction of blue OLEDs

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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