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@ARTICLE{Haags:874669,
author = {Haags, Anja and Rochford, Luke A. and Felter, Janina and
Blowey, Phil J. and Duncan, David Andrew and Woodruff, D
Phil and Kumpf, Christian},
title = {{G}rowth and {E}volution of {TCNQ} and {K} {C}oadsorption
{P}hases on {A}g(111)},
journal = {New journal of physics},
volume = {22},
issn = {1367-2630},
address = {[London]},
publisher = {IOP},
reportid = {FZJ-2020-01585},
pages = {063028},
year = {2020},
abstract = {Alkali-doping is a very efficient way of tuning the
electronic properties of active molecular layers in
(opto-)electronic devices based on organic semiconductors.
In this context, we report on the phase formation and
evolution of charge transfer salts formed by
7,7,8,8-tetracyanoquinodimethane (TCNQ) in coadsorption with
potassium on a Ag(111) surface. Based on an in-situ study
using low energy electron microscopy and diffraction we
identify the structural properties of four phases with
different stoichiometries, and follow their growth and
inter-phase transitions. We label these four phases α to
δ, with increasing K content, the last two of which (γ and
δ-phases) have not been previously reported. During TCNQ
deposition on a K-precovered Ag(111) surface we find a
superior stability of δ phase islands compared to the γ
phase; continued TCNQ deposition leads to direct transition
from the δ to the β-phase when the K:TCNQ ratio
corresponding to this phase regime is reached, with no
intermediate γ-phase formation. When, instead, K is
deposited on a surface precovered with large islands of the
low density commensurate (LDC) TCNQ phase that are
surrounded by a TCNQ 2D-gas, we observe two different
scenarios: On the one hand, in the 2D-gas phase regions,
very small α-phase islands are formed (close to the
resolution limit of the microscope, 10-15 nm), which
transform to β-phase islands of similar size with
increasing K deposition. On the other hand, the large
(micrometer-sized) TCNQ islands transform directly to
similarly large single-domain β-phase islands, the
formation of the intermediate α-phase being suppressed.
This frustration of the LDC-to-α transition can be lifted
by performing the experiment at elevated temperature. In
this sense, the morphology of the pure TCNQ submonolayer is
conserved during phase transitions.},
cin = {PGI-3},
ddc = {530},
cid = {I:(DE-Juel1)PGI-3-20110106},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000545698900001},
doi = {10.1088/1367-2630/ab825f},
url = {https://juser.fz-juelich.de/record/874669},
}