MOCVD-derived highly transparent, conductive zinc- and tin-doped indium oxide thin films: precursor synthesis, metastable phase film growth and characterization, and application as anodes in polymer light-emitting diodes.
Four diamine adducts of bis(hexafluoroacetylacetonato)zinc [Zn(hfa)(2).(diamine)] can be synthesized in a single-step reaction. Single crystal X-ray diffraction studies reveal monomeric, six-coordinate structures. The thermal stabilities and vapor phase transport properties of these new complexes are considerably greater than those of conventional solid zinc metal-organic chemical vapor deposition (MOCVD) precursors. One of the complexes in the series, bis(1,1,1,5,5,5-hexafluoro-2,4-pentadionato)(N,N'-diethylethylenediamine)zinc, is particularly effective in the growth of thin films of the transparent conducting oxide Zn-In-Sn-O (ZITO) because of its superior volatility and low melting point of 64 degrees C. ZITO thin films with In contents ranging from 40 to 70 cation % (a metastable phase) were grown by low-pressure MOCVD. These films exhibit conductivity as high as 2900 S/cm and optical transparency comparable to or greater than that of commercial Sn-doped indium oxide (ITO) films. ZITO films with the nominal composition of ZnIn(2.0)Sn(1.5)O(z)() were used in fabrication of polymer light-emitting diodes. These devices exhibit light outputs and current efficiencies almost 70% greater than those of ITO-based control devices.
Ni
Jun
J
Department of Chemistry, the Department of Electrical and Computer Engineering, and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, USA.
Yan
He
H
Wang
Anchuang
A
Yang
Yu
Y
Stern
Charlotte L
CL
Metz
Andrew W
AW
Jin
Shu
S
Wang
Lian
L
Marks
Tobin J
TJ
Ireland
John R
JR
Kannewurf
Carl R
CR