Details

Autor(en) / Beteiligte

• Kim, Sei-Yong
• Jeong, Won-Ik
• Mayr, Christian
• Park, Young-Seo
• Kim, Kwon-Hyeon
• Lee, Jeong-Hwan
• Moon, Chang-Ki
• Brütting, Wolfgang
• Kim, Jang-Joo

Titel

Organic Light-Emitting Diodes with 30% External Quantum Efficiency Based on a Horizontally Oriented Emitter

Ist Teil von

• Advanced functional materials, 2013-08, Vol.23 (31), p.3896-3900

Ort / Verlag

Weinheim: WILEY-VCH Verlag

Erscheinungsjahr

2013

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• High‐efficiency phosphorescent organic light‐emitting diodes (OLEDs) doped with Ir(ppy)2(acac) [bis(2‐phenylpyridine)iridium(III)‐acetylacetonate] in an exciplex forming co‐host have been optically analyzed. This emitter has a preferred orientation with the horizontal to vertical dipole ratio of 0.77:0.23 as compared to 0.67:0.33 in the isotropic case. Theoretical analysis based on the orientation factor (Θ, the ratio of the horizontal dipoles to total dipoles) and the photoluminescence quantum yield (qPL) of the emitter predicts that the maximum external quantum efficiency (EQE) of the OLEDs with this emitter is about 30%, which matches very well with the experimental data, indicating that the electrical loss of the OLEDs is negligible and the device structure can be utilized as a platform to demonstrate the validity of optical modeling. Based on the results, the maximum EQE achievable for a certain emitting dye in a host can be predicted by just measuring qPL and Θ in a neat film on glass without the need to fabricate devices, which offers a universal plot of the maximum EQE as a function of qPL and Θ. High‐efficiency phosphorescent organic light‐emitting diodes (OLEDs) doped with Ir(ppy)2(acac) in an exciplex forming co‐host have a preferred horizontal emitter orientation. Based on optical analysis a maximum efficiency of the OLEDs of about 30% is calculated, which matches very well with the experimental data. Furthermore, a simple method to predict the maximum efficiency achievable with a certain emitting dye in a host matrix is suggested.