Well-Ordered 4CzIPN ((4s,6s)-2,4,5,6-Tetra(9-H-carbazol-9-yl)isophthalonitrile) Layers: Molecular Orientation, Electronic Structure, and Angular Distribution of Photoluminescence

Y Hasegawa; Y Yamada; M Sasaki; T Hosokai; H Nakanotani; C Adachi

doi:10.1021/acs.jpclett.7b03232

Well-Ordered 4CzIPN ((4s,6s)-2,4,5,6-Tetra(9-H-carbazol-9-yl)isophthalonitrile) Layers: Molecular Orientation, Electronic Structure, and Angular Distribution of Photoluminescence

J Phys Chem Lett. 2018 Feb 15;9(4):863-867. doi: 10.1021/acs.jpclett.7b03232. Epub 2018 Feb 7.

Authors

Y Hasegawa¹, Y Yamada¹, M Sasaki¹, T Hosokai², H Nakanotani³, C Adachi³

Affiliations

¹ Institute of Pure and Applied Sciences, University of Tsukuba 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8573, Japan.
² National Institute of Advanced Industrial Science and Technology (AIST) 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8568, Japan.
³ Center for Organic Photonics and Electronics Research (OPERA), Kyushu University , 744 Motooka, Nishi, Fukuoka 819-0395, Japan.

PMID: 29370700
DOI: 10.1021/acs.jpclett.7b03232

Abstract

We fabricated a well-ordered homogeneous monolayer of disk-shaped, carbazolyl dicyanobenzene (CDCB)-based thermally activated delayed fluorescence (TADF) molecule, i.e., 4CzIPN((4s,6s)-2,4,5,6-tetra(9Hcarbazol-9-yl)isophthalonitrile) at room temperature on flat Ag(111), Au(111), and Cu(111) surfaces. The second layer of the 4CzIPN was also found to be well ordered. The electronic states of the well-ordered monolayer and multilayer of 4CzIPN were found to be nearly unchanged from that of the isolated molecule calculated by the density functional theory (DFT), suggesting that the ordered layers retain the TADF properties. Indeed, we demonstrated the delayed fluorescence and the nearly perfect in-plane alignment of the transition dipole moment of a 4CzIPN thin film on glass substrate even in an ambient condition. These results indicate that the well-ordered films of the disc-shaped carbazole-based TADF molecules could potentially be utilized in organic light-emitting diode (OLED) devices with high light outcoupling efficiency.