Electrochemical scanning tunneling microscopic studies of dye sensitized solar cells

Solar energy has seen tremendous increases in usage and development in the past few years. In order to bring down the production costs, new materials and processes are being reported each year, but the reported cell efficiency is still far less than what is required for commercialization. Study of the molecular behavior and nanoscale of these systems helps in understanding the functioning of solar cells. Scanning probe microscopic techniques provide a potential platform for such systems.;Electrochemical current mapping of the electrode surface revealed uneven current generation patterns along the surface of the nanowire. Higher J sc of 14.4microA was obtained using SnO2 nanowires modified with TiO2 nanoparticles. A Jsc of 9muA has been observed using the plain SnO2 nanowires indicating that current generation can be enhanced by changing the nanowire architectures.;The ability to detect current variation along and between electrode surface shows that the ECSTM technique can be used to obtain the spatial current generation on the electrode of the DSSCs and understand the electron transport behavior at the nanoscale.;Electrochemical Scanning Tunneling Microscopy (EC-STM) has been applied to study the photocurrent produced in a dye sensitized solar cell at the nanoscale. In ECSTM a Pt/Ir wire is used as the counter electrode, while the working electrode consists of a conducting metal oxide surface coated with a loose layer of sintered dye-sensitized SnO2 nanowires. ECSTM has been used to generate ions I/I3- couple electrolyte at the tip and the corresponding current generated between the tip and the sample is used to study the electron generation at the nanoscale over the electrode surface.