Nano Express

Nanoscale Research Letters

, 4:1475

First online:

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

Ultrafast Dynamics of Localized and Delocalized Polaron Transitions in P3HT/PCBM Blend Materials: The Effects of PCBM Concentration

  • Emmanouil LioudakisAffiliated withEnergy, Environment and Water Research Center, The Cyprus Institute Email author 
  • , Ioannis AlexandrouAffiliated withElectrical Engineering and Electronics, University of Liverpool
  • , Andreas OthonosAffiliated withResearch Center of Ultrafast Science, Department of Physics, University of Cyprus


Nowadays, organic solar cells have the interest of engineers for manufacturing flexible and low cost devices. The considerable progress of this nanotechnology area presents the possibility of investigating new effects from a fundamental science point of view. In this letter we highlight the influence of the concentration of fullerene molecules on the ultrafast transport properties of charged electrons and polarons in P3HT/PCBM blended materials which are crucial for the development of organic solar cells. Especially, we report on the femtosecond dynamics of localized (P2at 1.45 eV) and delocalized (DP2at 1.76 eV) polaron states of P3HT matrix with the addition of fullerene molecules as well as the free-electron relaxation dynamics of PCBM-related states. Our study shows that as PCBM concentration increases, the amplified exciton dissociation at bulk heterojunctions leads to increased polaron lifetimes. However, the increase in PCBM concentration can be directly related to the localization of polarons, creating thus two competing trends within the material. Our methodology shows that the effect of changes in structure and/or composition can be monitored at the fundamental level toward optimization of device efficiency.


Ultrafast Composites Fullerenes Polarons