Nano Express

Nanoscale Research Letters

, Volume 4, Issue 7, pp 635-639

Open Access This content is freely available online to anyone, anywhere at any time.

Monitoring Charge Exchange in P3HT-Nanotube Composites Using Optical and Electrical Characterisation

  • Ioannis AlexandrouAffiliated withElectrical Engineering and Electronics, University of Liverpool Email author 
  • , Emmanouil LioudakisAffiliated withDepartment of Physics, Research Center of Ultrafast Science, University of CyprusEnergy, Environment and Water Research Center, The Cyprus Institute
  • , Dimitrios DelaportasAffiliated withElectrical Engineering and Electronics, University of Liverpool
  • , C. Z. ZhaoAffiliated withElectrical Engineering and Electronics, University of Liverpool
  • , Andreas OthonosAffiliated withDepartment of Physics, Research Center of Ultrafast Science, University of Cyprus

Abstract

Charge exchange at the bulk heterojunctions of composites made by mixing single wall nanotubes (SWNTs) and polymers show potential for use in optoelectronic devices such as solar cells and optical sensors. The density/total area of these heterojunctions is expected to increase with increasing SWNT concentration but the efficiency of solar cell peaks at low SWNT concentrations. Most researchers use current–voltage measurements to determine the evolution of the SWNT percolation network and optical absorption measurements to monitor the spectral response of the composites. However, these methods do not provide a detailed account of carrier transport at the concentrations of interest; i.e., near or below the percolation threshold. In this article, we show that capacitance–voltage (CV) response of (metal)-(oxide)-(semiconducting composite) devices can be used to fill this gap in studying bulk heterojunctions. In an approach where we combine optical absorption methods with CV measurements we can acquire a unified optoelectronic response from P3HT-SWNT composites. This methodology can become an important tool for optoelectronic device optimization.