Abstract
This study explores the effect of molecular permanent dipole moment (PDM) on aggregation of guest molecules in phosphorescent host-guest organic light-emitting diodes (OLEDs). Through a combination of photoluminescence measurements, high-angle annular dark-field scanning transmission electron microscopy analysis, and an Ising model based physical vapor-deposition simulation, we show that higher PDM of tris[2-phenylpyridinato-C2,N]iridium(III) guest can actually lead to a reduced aggregation relative to tris[bis[2-(2-pyridinyl-N)phenyl-C] (acetylacetonato)iridium(III) when doped into a non-polar host 1,3,5-tris(carbazol-9-yl)benzene. This study further explores the effect of host polarity by using a polar host 3′,5′-di(carbazol-9-yl)-[1,1′-biphenyl]-3,5-dicarbonitrile, and it is shown that the polar host leads to reduced guest aggregation. This study provides a comprehensive understanding of the impact of molecular PDM on OLED material efficiency and stability, providing insights for optimizing phosphorescent OLED materials.
| Original language | English |
|---|---|
| Article number | 244304 |
| Journal | Journal of Chemical Physics |
| Volume | 160 |
| Issue number | 24 |
| DOIs | |
| State | Published - Jun 28 2024 |
Funding
Theory development and analysis was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award No. DE-SC0018021. Device fabrication, TRPL measurement capabilities, and our high-performance computing node were funded by Universal Display Corporation (UDC). The HAADF-STEM portion of this research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a U.S. Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory.