| A relatively new type of photovoltaic device is the dye sensitized solar cell (DSSC), or Graetzel cell. Although less expensive to produce than traditional solar cells, the efficiency of DSSCs must be improved substantially to compete effectively with the more expensive conventional silicon-based cells. A considerable amount of research has been done to elucidate the chemistry that takes place in DSSCs, and thereby determine how efficiency may be improved. Two competing mechanisms, which require different conditions for optimum performance, have been proposed to explain the observed ultrafast electron transfer (ET) between the dye and the semiconductor. In order to investigate the importance of these two proposed mechanisms with computational chemistry, it is necessary to apply a method in which the population of the various adiabatic states may evolve over time. Non-adiabatic (NA) molecular dynamics (MD), in which transitions between adiabatic states are calculated via the NA coupling, provides a manner in which the relative importance of the adiabatic and NA pathways may be evaluated. Three computational chemistry studies of the ultrafast ET in DSSCs using a quantum-classical mean-field approach are presented. The first study simulates ultra-high vacuum (UHV) conditions and uses isonicotinic acid as the molecular electron donor (MED). The second study investigates room temperature conditions using isonicotinic acid silver cyanide as the MED. The third study reproduces the experimental results reported for the alizarin TiO2 system. |
