Highly efficient nanocrystalline ZnO thin films prepared by a novel method and their application in dye-sensitized solar cells

Nanostructured ZnO aggregates are synthesized under controlled conditions using zinc acetate dihydrate and 1-butanol as the starting materials and triethylamine as precipitating agent. Thin films were formed by a doctor-blade technique. The phase and morphology were investigated by using SEM and XRD. These films, derivatized by N719 dye, (Bu4N)(2)[Ru(dcbpyH)(2)(NCS)(2)], were used to construct sandwich-type dye-sensitized solar cells (DSSCs) and their photoelectrochemical characteristics were determined. The photocurrent, photovoltage and power conversion efficiency characteristics for the DSSCs were measured under illumination by light of varied irradiance power. With a typical cell, V (OC)=0.518 V, J (SC)=11.1 mA cm(-2), fill factor (FF)=0.50, overall conversion efficiency (eta)=0.69 % and incident photon to current conversion efficiency (IPCE)=35 % were achieved under full light illumination (430 mW cm(-2)) and V (OC)=0.516 V, J (SC)=8.72 mA cm(-2), fill factor 0.54 and overall conversion efficiency eta=0.64 % were achieved under visible light illumination (380 mW cm(-2)). With the use of a thin ZnO film prepared during the present work, improved results have been achieved than many of the earlier reported ones. The good structural quality (crystallinity, densely packed spherical grains, lack of voids, nanometer-size crystallites etc.) of our thin films is mainly responsible for their better photoactivity.