TY - JOUR
T1 - Random organic nano-textured microstructures formed by photoexcitation for light extraction of blue OLEDs
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
KW - Organic light-emitting diodes
KW - Photoinduced charge transfer
UR - http://www.scopus.com/inward/record.url?scp=85090736597&partnerID=8YFLogxK
U2 - 10.1016/j.orgel.2020.105892
DO - 10.1016/j.orgel.2020.105892
M3 - Article
AN - SCOPUS:85090736597
SN - 1566-1199
VL - 87
JO - Organic Electronics: physics, materials, applications
JF - Organic Electronics: physics, materials, applications
M1 - 105892
ER -