Abstract
The efficiency of organic light-emitting diodes (OLEDs) is especially limited by their low light outcoupling efficiency. An approach for its enhancement is the use of horizontally oriented emitter molecules with respect to the substrate. In this study we quantitatively determine the orientation of the optical transition dipole moments in doped films of two similar phosphorescent Pt(II) complexes having a linear molecular structure. These emitters are employed in OLED devices and their efficiency is analyzed by optical simulations. For an OLED with slightly more horizontally oriented emitter molecules an external quantum efficiency (ηEQE) of 15.8% at low current-density is realized, indicating a relative improvement of outcoupling efficiency of 5.3% compared to the isotropic case. However, a very similar complex adopting isotropic molecular orientation yields ηEQEof only 11.5% implying an imperfect charge carrier balance in the OLED device and a shift of the recombination zone. Furthermore, we highlight the enormous potential of horizontal molecular orientation of emitting molecules in OLEDs.
| Original language | English |
|---|---|
| Pages (from-to) | 3031-3037 |
| Number of pages | 7 |
| Journal | Organic Electronics |
| Volume | 15 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - Jan 1 2014 |
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All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Biomaterials
- Chemistry(all)
- Condensed Matter Physics
- Materials Chemistry
- Electrical and Electronic Engineering
Cite this
Different orientation of the transition dipole moments of two similar Pt(II) complexes and their potential for high efficiency organic light-emitting diodes. / Mayr, Christian; Taneda, Masatsugu; Adachi, Chihaya; Brütting, Wolfgang.
In: Organic Electronics, Vol. 15, No. 11, 01.01.2014, p. 3031-3037.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Different orientation of the transition dipole moments of two similar Pt(II) complexes and their potential for high efficiency organic light-emitting diodes
AU - Mayr, Christian
AU - Taneda, Masatsugu
AU - Adachi, Chihaya
AU - Brütting, Wolfgang
PY - 2014/1/1
Y1 - 2014/1/1
N2 - The efficiency of organic light-emitting diodes (OLEDs) is especially limited by their low light outcoupling efficiency. An approach for its enhancement is the use of horizontally oriented emitter molecules with respect to the substrate. In this study we quantitatively determine the orientation of the optical transition dipole moments in doped films of two similar phosphorescent Pt(II) complexes having a linear molecular structure. These emitters are employed in OLED devices and their efficiency is analyzed by optical simulations. For an OLED with slightly more horizontally oriented emitter molecules an external quantum efficiency (ηEQE) of 15.8% at low current-density is realized, indicating a relative improvement of outcoupling efficiency of 5.3% compared to the isotropic case. However, a very similar complex adopting isotropic molecular orientation yields ηEQEof only 11.5% implying an imperfect charge carrier balance in the OLED device and a shift of the recombination zone. Furthermore, we highlight the enormous potential of horizontal molecular orientation of emitting molecules in OLEDs.
AB - The efficiency of organic light-emitting diodes (OLEDs) is especially limited by their low light outcoupling efficiency. An approach for its enhancement is the use of horizontally oriented emitter molecules with respect to the substrate. In this study we quantitatively determine the orientation of the optical transition dipole moments in doped films of two similar phosphorescent Pt(II) complexes having a linear molecular structure. These emitters are employed in OLED devices and their efficiency is analyzed by optical simulations. For an OLED with slightly more horizontally oriented emitter molecules an external quantum efficiency (ηEQE) of 15.8% at low current-density is realized, indicating a relative improvement of outcoupling efficiency of 5.3% compared to the isotropic case. However, a very similar complex adopting isotropic molecular orientation yields ηEQEof only 11.5% implying an imperfect charge carrier balance in the OLED device and a shift of the recombination zone. Furthermore, we highlight the enormous potential of horizontal molecular orientation of emitting molecules in OLEDs.
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U2 - 10.1016/j.orgel.2014.07.042
DO - 10.1016/j.orgel.2014.07.042
M3 - Article
VL - 15
SP - 3031
EP - 3037
JO - Organic Electronics: physics, materials, applications
JF - Organic Electronics: physics, materials, applications
SN - 1566-1199
IS - 11
ER -