6.6 International Exchange Visits

Project Coordinator: 
University of Queensland
Chief Investigators: 
Martin Stolterfoht

year, the ACAP Management Committee selects an ACAP node to have the opportunity to nominate a student, post-doctoral or early researcher for an international exchange visit to work with one of our US partner institutes. Alternatively nodes can nominate a US candidate to come to work with an ACAP institute. Mr Martin Stolterfoht, from the University of Queensland node, visited NREL in 2015. 

The objective of our partners at NREL, Dr Nikos Kopidakis (head of the Organic PV group) and Dr Bryon Larson (postdoctoral research fellow), was to set up a charge transport measurement technique that had been developed at UQ (Stolterfoht et al. 2014; Philippa et al. 2014). The “resistance dependent photovoltage (RPV)” technique allows the quantification of charge carrier mobilities in operational organic solar cells under relevant conditions. 

The aim of the visiting student, Martin Stolterfoht, was to continue his investigations on the dissociation of the so-called charge-transfer (CT) states, a critical step in the generation process of free charges in blends of organic  semiconductors. NREL’s expertise on time resolved microwave conductivity (TRMC) Savenije 2013) measurements allows one to probe the product of “local” charge carrier mobilities (on an nm-length scale) and the generation yield of free charges after a short laser excitation. A donor:acceptor blend ratio study was chosen, with the intention to relate the local charge carrier dynamics with the carrier moblities on hundreds of nm-length scales and the quantum yield of photogenerated charges.