Simultaneous study of exciton dissociation and charge transport in a light harvesting assembly: Lead selenide nanocrystal/zinc oxide interface

• Simultaneous study of exciton dissociation and charge was carried out.
• Surface ligand dependent exciton dissociation was probed using transistor devices.
• We demonstrate that shorter ligands are more favorable to exciton dissociation.

Simultaneous study of exciton dissociation between lead selenide (PbSe) and zinc oxide (ZnO) nanocrystals, and charge transport in the electron acceptor (ZnO) was carried out using the field effect transistor (FET) arrangement in which a bi-layer of PbSe and ZnO is formed onto the SiO2 substrate. Using multiple potential probes between the source and drain electrodes, change in the electrical conductance in the ZnO, proportional to exciton dissociation at the electron donor/acceptor (PbSe/ZnO) interface, was measured excluding the Au/ZnO contact resistance. Surface ligand capping dependent exciton dissociation at the ethanedithiol-treated PbSe/ZnO interface was compared with the biphenyl-4,4′-dithiol-treated PbSe/ZnO interface using the FET geometry, demonstrating that a shorter ligand is more favorable to exciton dissociation. From the light intensity dependent conductivity change in the ZnO layer, the origin of carrier recombination is discussed.