Tuning the hole injection barrier at the organic/metal interface with self-assembled functionalized aromatic thiols.
Self-assembled functionalized aromatic thiols (oligophenylenes composed of building blocks of dimethoxy-substituted phenylenes, perfluoro-substituted phenylenes, and a terminal thiol group) were used to tune the hole injection barrier (Delta(h)) of copper(II) phthalocyanine (CuPc) on Au(111). Synchrotron-based high-resolution photoemission spectroscopy study reveals a significant reduction of Delta(h) by as much as 0.75 eV from Delta(h) = 0.9 eV for CuPc/Au(111) to Delta(h) = 0.15 eV for CuPc/BOF/Au(111), where BOF represents 4-pentafluorophenyl-1-(p-thiophenyl)-2,5-dimethoxybenzene. The delocalized pi orbitals of these functionalized aromatic thiols greatly facilitate effective charge transfer (hole or electron) across the SAM interface as compared to alkanethiols, hence making this novel interface modification scheme a simple and effective way to tune the hole injection barrier. This method has potential applications in molecular electronics, organic light-emitting diodes (OLED), organic field-effect transistors (OFETs), and organic solar cells.
Chen
Wei
W
Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore.
Huang
Chun
C
Gao
Xing Yu
XY
Wang
Li
L
Zhen
Chang Gua
CG
Qi
Dongchen
D
Chen
Shi
S
Zhang
Hong Liang
HL
Loh
Kian Ping
KP
Chen
Zhi Kuan
ZK
Wee
Andrew Thye Shen
AT