Influence of Layer Thickness to the Emission Spectra in Microcavity Organic Light Emitting Diodes

Author

Kwong, C.Y. ; Djurisic, A.B. ; Cheung, C.H. ; Chan, J. ; Rakic, A.D. ; Tam, H.L. ; Cheah, K.W. ; Liu, Z.T. ; Chan, W.K. ; Chui, P.C.

Author_Institution

Dept. of Electr. & Electron. Eng., Hong Kong Univ.

fYear

2004

fDate

8-10 Dec. 2004

Firstpage

347

Lastpage

350

Abstract

Microcavity organic light emitting diodes (OLEDs) have attracted great attention because they can reduce the width of emission spectra from organic materials enhance brightness and achieve multipeak emission from the same material. In this work, we have fabricated microcavity OLEDs with widely used organic materials, such as N,N´-di(naphthalene-1-yl)-N,N´-diphenylbenzidine (NPB) as a hole transport layer and tris (8-hydroxyquinoline) (Alq) as emitting and electron transporting layer. These organic materials are sandwiched either between two thick silver mirrors or one thin copper and one thick silver mirrors. The influence of total cavity length (from 164 nm to 243 nm) and the cavity Q-factor to the emission behavior has been investigated. In all cases, an OLED without bottom mirror, i.e. with the organic materials sandwiched between indium tin oxide and a thick silver mirror, has been fabricated for comparison. We have characterized the devices with photoluminescence, electroluminescence, and reflectance measurements. Multiple peaks have been observed for some devices at larger viewing angles

Keywords

Q-factor; electroluminescence; microcavities; mirrors; organic compounds; organic light emitting diodes; photoluminescence; reflectivity; 164 to 243 nm; N,N´-di(naphthalene-1-yl)-N,N´-diphenylbenzidine; brightness; cavity Q-factor; copper mirror; electroluminescence; electron transport layer; emission spectra; emitting layer; hole transport layer; indium tin oxide; layer thickness; microcavity OLED; multipeak emission; organic light emitting diodes; organic materials; photoluminescence; reflectance measurements; silver mirrors; tris (8-hydroxyquinoline); viewing angles; Brightness; Charge carrier processes; Copper; Electron emission; Microcavities; Mirrors; Organic light emitting diodes; Organic materials; Q factor; Silver; OLED; microcavity;

fLanguage

English

Publisher

ieee

Conference_Titel

Optoelectronic and Microelectronic Materials and Devices, 2004 Conference on

Conference_Location

Brisbane, Qld.

Print_ISBN

0-7803-8820-8

Type

conf

DOI

10.1109/COMMAD.2004.1577562

Filename

1577562