Ultrafast Electron Transfer at Organic Semiconductor Interfaces: Importance of Molecular Orientation.
Much is known about the rate of photoexcited charge generation in at organic donor/acceptor (D/A) heterojunctions overaged over all relative arrangements. However, there has been very little experimental work investigating how the photoexcited electron transfer (ET) rate depends on the precise relative molecular orientation between D and A in thin solid films. This is the question that we address in this work. We find that the ET rate depends strongly on the relative molecular arrangement: The interface where the model donor compound copper phthalocyanine is oriented face-on with respect to the fullerene C60 acceptor yields a rate that is approximately 4 times faster than that of the edge-on oriented interface. Our results suggest that the D/A electronic coupling is significantly enhanced in the face-on case, which agrees well with theoretical predictions, underscoring the importance of controlling the relative interfacial molecular orientation.
['Ayzner|Alexander L|AL|', 'Nordlund|Dennis|D|', 'Kim|Do-Hwan|DH|', 'Bao|Zhenan|Z|', 'Toney|Michael F|MF|']
charge-transfer state core-hole clock electron dynamics organic photovoltaic resonant Auger resonant photoemission