Publication Date

1-3-2020

Department

Ames Laboratory; Physics and Astronomy; Electrical and Computer Engineering; Microelectronics Research Center (MRC)

Campus Units

Ames Laboratory, Physics and Astronomy, Electrical and Computer Engineering, Microelectronics Research Center (MRC)

OSTI ID+

1575203

Report Number

IS-J 10049

DOI

10.1002/adom.201901282

Journal Title

Advanced Optical Materials

Volume Number

8

Issue Number

1

First Page

0191282

Abstract

Very bright (≈14 000 cd m−2) deep blue exciplex organic light emitting diodes (OLEDs) peaking at ≈435 nm, where the photopic response is ≈0.033, and with CIE color coordinates (0.1525, 0.0820), are described. The OLED properties are interestingly linked to PPh3O (triphenylphosphine oxide) and attributes of the emitting layer (EML) comprising NPB interfacing host:guest TPBi:PPh3O 5:1 weight ratio. A neat PPh3O layer that is central for device performance follows the EML (NPB/TPBi:PPh3O 5:1/PPh3O). The bright electroluminescence originates from NPB/TPBi:PPh3O exciplexes involving triplets via thermally activated delayed fluorescence, as evident from the strong quenching of the photoluminescence (PL) by oxygen and interestingly, the monomolecular emission process. The transient PL decay times of a NPB/TPBi:PPh3O 5:1/PPh3O film are 43 ns in air versus 136, 610, and weak ≈2000 ns in N2. For comparison, the respective PL decay times of films of NPB:TPBi are 16 ns in air versus 131 and 600 ns in N2, and of NPB:PPh3O they are 29 ns in air versus 56, 483, and weak ≈2000 ns in N2. It is suspected that slow emitting states are associated with a PPh3O aggregate interacting with NPB.

DOE Contract Number(s)

AC02‐07CH11358; ECCS 1202309

Language

en

Publisher

Iowa State University Digital Repository, Ames IA (United States)

Included in

Optics Commons

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