Effect of p-Type Semiconductor Electrode on Photovoltaic Properties in n/p Tandem-Type Dye-Sensitized Solar Cell

Abstract

To improve the light-to-electric energy conversion efficiency of a dye-sensitized solar cell, a p-type semiconductor electrode was introduced to the cell so that n/p tandem-type solar cell was composed. In the tandem cell, the TiO2 adsorbed with N719 dye molecules and the p-type semiconductor were used an anode and a cathode, respectively, and acetonitrile solution containing iodide was done as an electrolyte. The cathode was prepared on a surface of platinum layer formed on a FTO glass plate by plasma spattering CuxBiyOz as the p-type semiconductor. Short-circuit current density and conversion efficiency of the tandem cell were larger than those in a cathode without the p-type semiconductor layer. The p-type semiconductor layer will be able to absorb low energy photons passed through the anode. After ZnO particles were coated on a surface of the p-type semiconductor layer, open-circuit voltage was increased. Such coating of the particles will be effective to depress a back-transfer at the interface between the p-type semiconductor layer and the electrolyte and band-bending of the p-type semiconductor.