Light-Enhanced Charge Mobility in a Molecular Hole Transporter

We present an investigation into the charge transport through a molecular hole transporter. Under illumination, photoinduced charge transfer occurs from a sensitizer to the hole transporter. The increased hole density results in striking enhancements in film conductivity, up to ${10}^6$, and charge carrier mobility, up to ${10}^3$. Such enhancements in mobility at low charge densities have not previously been observed in molecular semiconductors, and demonstrate the importance of considering a charge-density dependent mobility in molecular semiconductors employed under photovoltaic operation.