TY - JOUR
T1 - Increased light outcoupling efficiency in dye-doped small molecule organic light-emitting diodes with horizontally oriented emitters
AU - Frischeisen, Jörg
AU - Yokoyama, Daisuke
AU - Endo, Ayataka
AU - Adachi, Chihaya
AU - Brütting, Wolfgang
N1 - Funding Information:
We acknowledge financial support by the Elite Network of Bavaria through the international graduate school “Materials Science of Complex Interfaces” and by the Japan Society for the Promotion of Science (JSPS). This work was partly supported by Promotion of Environmental Improvement for Independence of Young Researchers Program of Ministry of Education, Culture, Sports, Science and Technology, Japan . We thank Prof. Junji Kido for using the ultraviolet photoelectron spectroscopy setup in his lab at Yamagata University, Japan. We also thank the Research Center for Computational Science (RCCS), Okazaki National Research Institutes, for the use of a SGI Altix4700 computer.
PY - 2011/5
Y1 - 2011/5
N2 - Small molecule organic light-emitting diodes (SM-OLEDs) are efficient large area light sources facing their market entry. However, a low light outcoupling efficiency of typically 20% still strongly limits device performance. Here, we highlight the potential of employing dye-doped emission layers with emitting molecules having horizontally oriented transition dipole moments. The effect of molecular orientation is explained by studying optical simulations that distinguish between horizontal and vertical dipole orientation. In addition, an experimental method that enables straightforward determination of dipole orientation in guest-host systems is presented and used for the analysis of two materials that are very similar except for their orientation. By measuring the external electroluminescence quantum efficiency of SM-OLEDs based on these materials, evidence is found that a mainly horizontal dipole orientation enhances light outcoupling by around 45%. Furthermore, the effect of orientation in SM-OLEDs offers many additional benefits concerning stack design and has fundamental implications for material choice.
AB - Small molecule organic light-emitting diodes (SM-OLEDs) are efficient large area light sources facing their market entry. However, a low light outcoupling efficiency of typically 20% still strongly limits device performance. Here, we highlight the potential of employing dye-doped emission layers with emitting molecules having horizontally oriented transition dipole moments. The effect of molecular orientation is explained by studying optical simulations that distinguish between horizontal and vertical dipole orientation. In addition, an experimental method that enables straightforward determination of dipole orientation in guest-host systems is presented and used for the analysis of two materials that are very similar except for their orientation. By measuring the external electroluminescence quantum efficiency of SM-OLEDs based on these materials, evidence is found that a mainly horizontal dipole orientation enhances light outcoupling by around 45%. Furthermore, the effect of orientation in SM-OLEDs offers many additional benefits concerning stack design and has fundamental implications for material choice.
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U2 - 10.1016/j.orgel.2011.02.005
DO - 10.1016/j.orgel.2011.02.005
M3 - Article
AN - SCOPUS:79952569231
SN - 1566-1199
VL - 12
SP - 809
EP - 817
JO - Organic Electronics: physics, materials, applications
JF - Organic Electronics: physics, materials, applications
IS - 5
ER -