Molecular Stacking Induced by Intermolecular C–H···N Hydrogen Bonds Leading to High Carrier Mobility in Vacuum‐Deposited Organic Films

Abstract

Simple bottom-up fabrication processes for molecular self-assembly have been developed for the construction of higher-order structures using organic materials, and have contributed to maximization of the potential of organic materials in chemical and bioengineering. However, their application to organic thin-fi lm devices such as organic light-emitting diodes have not been widely considered because simple fabrication of a solid fi lm containing an internal self-assembly structure has been regarded as diffi cult. Here it is shown that the intermolecular C-H · · · N hydrogen bonds can be simply formed even in vacuum-deposited organic fi lms having fl at interfaces. By designing the molecules containing pyridine rings properly for the intermolecular interaction, one can control the molecular stacking induced by the intermolecular hydrogen bonds. It is also demonstrated that the molecular stacking contributes to the high carrier mobility of the fi lm. These fi ndings provide new guidelines to improve the performance of organic optoelectronic devices and open up the possibilities for further development of organic devices with higher-order structures.

Tunable molecular orientation and elevated thermal stability of vapor-deposited organic semiconductors

“…It is possible that liquid-crystal-forming molecules or systems with specific intermolecular interactions will exhibit orientation trends distinct from those found here, and this would be a further route toward control of molecular anisotropy in glassy solids. Highthroughput experiments that directly measure charge mobility (16)(17)(18) would complement the results presented here.…”

“…Oriented materials can increase light outcoupling by a factor of 1.5 by directing emission out of the plane of the device (10)(11)(12)(13)(14). It has also been shown that oriented layers can improve device lifetime (15) and charge mobility (16)(17)(18). Given the potential utility of controlling molecular orientation in device layers (4,5,7), it is desirable to understand the extent to which molecular orientation can be tuned in glasses made from a particular compound and the mechanistic origins of this effect.…”

Efficient exciplex emission from intramolecular charge transfer material

“…These modest energy levels enable us to design serial devices with consecutive individual emitting spectra. Three electron acceptors, including 2,4,6-tris (biphenyl-3-yl)-1,3,5-triazine (T2T), bis-4,6-(3,5-di-4-pyridyl-phenyl)-2-methylpyrimidine (B4PyMPm) and PO-T2T and one electron donor N,N 0 -diphenyl-N,N 0 -bis(3-methylphenyl)-1,1 0 -biphenyl-4,4 0 -diamine (TPD) were chosen to form exciplex with DMAC-DPS to modulate the emitting spectra [18,25,26]. The molecular structures of DMAC-DPS, T2T, B4PyMPm, PO-T2T and TPD are given in Fig.…”

Phosphorescent dye-based supramolecules for high-efficiency organic light-emitting diodes

“…The optical anisotropy with different ordinary and extraordinary refractive indices was measured by variable angle spectroscopic ellipsometry (VASE), and the data indicated that the molecular long axes of the host molecules were parallel to the substrate (Supplementary Fig. 1) 26 . Because the EML contains a small amount of red dyes (B0.035 mol fraction), the molecular orientations of the red dyes and their resultant electro-optic performance rely on the binding geometries of the red dyes with ARTICLE the host molecules.…”