Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA.
Chemphyschem. 2013 Aug 26;14(12):2777-85. doi: 10.1002/cphc.201300293. Epub 2013 Jun 21.
When a phospholipid monolayer containing a zinc-coordinated porphyrin species formed atop a self-assembled monolayer of heptadecafluoro-1-decanethiol (CF3(CF2)7(CH2)2SH) 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.
当含有锌配位卟啉物种的磷脂单层在自组装的十七氟-1-十一硫醇（CF3(CF2)7(CH2)2SH）单层上形成时，会观察到显著的调制效应。与包含类似光活性脂质单层但形成在 1-十一硫醇 SAM 上的器件相比，这些氟化混合双层产生了 >60%的阴极电流增加和类似的阳极电流减少。从这些混合双层记录的光伏电压以相同的方式变化。这些混合双层基器件中光伏响应的调制可以通过与本研究中使用的硫醇相关的相反表面偶极来解释，在一种情况下（氟硫醇）增加，在另一种情况下（烷硫醇）减少了底层金基底的功函数。如果富勒烯作为这些器件中的光致剂，则也会观察到光伏/光电流调制的类似趋势。我们的结果揭示了定向表面偶极在影响光伏过程中的复杂性，以及其与光致剂相关的其他因素（例如它们在有机基质中的位置和取向）之间的微妙相互作用。
