Enhanced Triplet-Triplet Annihilation of Blue Fluorescent Organic Light-Emitting Diodes by Generating Excitons in Trapped Charge-Free Regions

Hyoungcheol Lim; Hyung Jin Cheon; Gyeong Seok Lee; Mikyung Kim; Yun-Hi Kim; Jang-Joo Kim

doi:10.1021/acsami.9b15303

Enhanced Triplet-Triplet Annihilation of Blue Fluorescent Organic Light-Emitting Diodes by Generating Excitons in Trapped Charge-Free Regions

ACS Appl Mater Interfaces. 2019 Dec 26;11(51):48121-48127. doi: 10.1021/acsami.9b15303. Epub 2019 Dec 11.

Authors

Hyoungcheol Lim, Hyung Jin Cheon¹, Gyeong Seok Lee¹, Mikyung Kim², Yun-Hi Kim¹, Jang-Joo Kim

Affiliations

¹ School of Materials Science and Engineering , Gyeongsang National University , 501, Jinju-daero , Jinju-si 660-701 , Gyeongsangnam-do , South Korea.
² Samsung Display Company, Limited , 95 Samsung 2-ro , Giheung-gu, Yongin-si 446-711 , Gyeonggi-Do , South Korea.

PMID: 31774270
DOI: 10.1021/acsami.9b15303

Abstract

Three new anthracene-cored molecules, 3,3'-(5-(10-(naphthalen-1-yl)anthracen-9-yl)-1,3-phenylene)dipyridine (AP3Py-Na), 3,3'-(5-(10-(naphthalen-2-yl)anthracen-9-yl)-1,3-phenylene)dipyridine (AP3Py-2Na), and 9,10-bis(3,5-di(pyridin-3-yl)phenyl)anthracene (ADP3Py), were synthesized to be used as an efficiency-enhancement layer (EEL) in blue fluorescent organic light-emitting diodes. Insertion of a very thin EEL (3 nm) between the deep blue emitting layer (EML) and the electron transport layer enhanced the external quantum efficiency (EQE) of the blue device by 44% compared to the device without the EEL, resulting in an EQE of 7.9% and a current efficiency of 9.0 cd A^-1 at 1000 cd m^-2; the CIE coordinates of the emitting color were (0.13, 0.14). The transient electroluminescence showed that the efficiency enhancement originates from the triplet-triplet annihilation (TTA) process in the EEL, followed by energy transfer to the emitting dye in the EML.

Keywords: anthracene; blue fluorescent; efficiency enhancement layer; organic light emitting diodes; triplet−triplet annihilation.