Understanding and predicting the orientation of heteroleptic phosphors in organic light-emitting materials
(Conference Presentation)

Tobias D. Schmidt; Matthew Jurow; Christian Mayr; Thomas Lampe; Peter I. Djurovic; Mark E. Thompson; Wolfgang Brütting

doi:10.1117/12.2236218

3 November 2016 Understanding and predicting the orientation of heteroleptic phosphors in organic light-emitting materials (Conference Presentation)

Tobias D. Schmidt, Matthew Jurow, Christian Mayr, Thomas Lampe, Peter I. Djurovic, Mark E. Thompson, Wolfgang Brütting

Author Affiliations +

Proceedings Volume 9941, Organic Light Emitting Materials and Devices XX; 99410R (2016) https://doi.org/10.1117/12.2236218
Event: SPIE Organic Photonics + Electronics, 2016, San Diego, California, United States

Abstract

Organic light-emitting diodes (OLEDs) have made tremendous progress in recent years. The internal quantum efficiency was continuously improved and is nowadays close to the ideal value of unity in state-of-the-art OLEDs. However, still only a small fraction of the internally generated power can be used for lighting aspects as most of the light is captured inside the device due to low outcoupling factors of typically 25%. One promising approach to increase this limiting factor is using an anisotropic orientation of the dye molecules. In particular, horizontal orientation of transition dipole vectors (TDV) of the emitting species is a powerful tool to improve the efficiency of OLEDs. In order to understand the underlying mechanisms for emitter orientation of heteroleptic phosphors, we compared the anisotropy factor of emissive guest/host systems prepared by thermal evaporation using different Ir-complexes incorporating coumarin and phenylpyridin based ligands. These molecules exhibit similar high permanent dipole moments and electrostatic surface potentials but differ in their molecular structure. Interestingly, only molecules with both aromatic and aliphatic ligands show non-isotropic distributions of their TDVs when co-deposited with a matrix material. From these findings we conclude that molecular orientation of heteroleptic Ir-complexes occurs instantaneously at the surface of the growing film and is driven by chemical interactions with the surrounding media, i.e. the vacuum and the aromatic matrix side. Furthermore, it is possible to predict the anisotropy factor for arbitrary molecular orientation with a mathematical model taking into account the geometrical distribution of the TDV on the molecules.

Conference Presentation

Citation Download Citation

Tobias D. Schmidt, Matthew Jurow, Christian Mayr, Thomas Lampe, Peter I. Djurovic, Mark E. Thompson, and Wolfgang Brütting "Understanding and predicting the orientation of heteroleptic phosphors in organic light-emitting materials (Conference Presentation)", Proc. SPIE 9941, Organic Light Emitting Materials and Devices XX, 99410R (3 November 2016); https://doi.org/10.1117/12.2236218

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
PRESENTATION

WATCH
PRESENTATION SAVE TO MY LIBRARY

GET CITATION

KEYWORDS

Molecules

Organic light emitting diodes

Anisotropy

Internal quantum efficiency

Light sources and illumination

Mathematical modeling

Molecular interactions

Show All Keywords

Keywords/Phrases

Search In:

Publication Years