The interface is inevitably formed when two dissimilar materials are brought into contact. In general, an interface can provide necessary electrical polarizations, electronic energy offsets, and thermal scattering. Therefore, interface is a key issue in controlling photovoltaic and thermoelectric processes in organic materials. In organic solar cells, the interface can exist between donor and acceptor materials and also between organic and electrode thin films. We found that the local polarizations at donor:acceptor interface can essentially determine the electron-hole binding energies in charge dissociation. Furthermore, we showed that the dielectric interaction at organic/electrode interface plays a critical role in collecting charge carriers towards the generation of photocurrent. By tuning the donor:acceptor and organic/electrode interfaces, we demonstrated a significant enhancement on photovoltaic efficiencies up to 9% (figure 1). In organic thermoelectric devices, we found the interface formed between low thermal-conducting polymer and high electrical-conducting metal can provide a mechanism to separately control electrical and thermal conductivities towards the development of thermoelectric functions. We demonstrated a large enhancement on Seebeck effect (> 500 mV/K) by engineering desirable polymer/metal interface in hybrid multi-layer metal/polymer/metal thin-film devices. In summary, this presentation will discuss the effects of interface on photovoltaic and Seebeck functions in organic solar cells and thermoelectric devices.

Interface enhanced photovoltaic and Seebeck effects in organic solar cells and thermoelectric devices

247th National Meeting (2014)

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