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Effects of Oriented Surface Dipole on Photoconversion Efficiency in an Alkane/Lipid‐Hybrid‐Bilayer‐Based Photovoltaic Model System
Author(s) -
Liu Lixia,
Xie Hong,
Bostic Heidi E.,
Jin Limei,
Best Michael D.,
Zhang X. Peter,
Zhan Wei
Publication year - 2013
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201300293
Subject(s) - alkane , dipole , photovoltaic system , bilayer , lipid bilayer , surface (topology) , chemical physics , model system , chemistry , materials science , nanotechnology , membrane , computational chemistry , hydrocarbon , organic chemistry , geometry , mathematics , biology , ecology , biochemistry
Abstract When a phospholipid monolayer containing a zinc‐coordinated porphyrin species formed atop a self‐assembled monolayer of heptadecafluoro‐1‐decanethiol (CF 3 (CF 2 ) 7 (CH 2 ) 2 SH) is subjected to photoelectrochemical current generation, a significant modulation effect is observed. Compared with devices that contain similar photoactive lipid monolayers but formed on 1‐dodecanethiol SAMs, these fluorinated hybrid bilayers produce a >60 % increase in cathodic currents and a similar decrease in anodic currents. Photovoltages recorded from these hybrid bilayers are found to vary in the same fashion. The modulation of photovoltaic responses in these hybrid‐bilayer‐based devices is explained by the opposite surface dipoles associated with the thiols employed in this study, which in one case (fluorothiol) increase and in another (alkanethiol) decrease the work function of the underlying gold substrates. A similar trend of photovoltage/photocurrent modulation is also observed if fullerene is used as the photoagent in these devices. Our results reveal the intricacy of orientated surface dipole in influencing the photovoltaic processes, and its subtle interplay with other factors related to the photoagents, such as their location and orientation within the organic matrix.