Zinc Oxide thin films for dye-sensitized solar cell applications

Abstract

The sun is an abundant, continuous and clean source of energy that can be tapped at liberty to produce electricity using many different photovoltaic designs. This research project probes into ZnO based dye sensitized solar cells (DSSCs), which are the most promising ? amongst the new class of nanostructured solar cells that offer the potential for high efficiency a at low cost. As against Conventional DSSCs, which use a TiO₂, nanoparticle film sensitized with a monolayer of dye molecules to transport electrons to the anode by a hopping “mechanism, this study was focused on ZnO as a more efficient alternative to TiO₂

Here TiO₂ film is replaced with ZnO. For comparison, ZnO particles were used in three sizes; 30 nm, 90 nm and 140 nm. Most of the DSSCs have given best results with Ruthenium dye complexes, and in this study in addition to Ruthenium N719, Indoline D102 was also used separately. Besides semiconductor and the dye, electrolyte was also altered in two types; liquid electrolyte and the Polymer electrolyte. Using all these combinations, 12 types of sample solar cells were designed for the study.

Study was conducted as a laboratory research by preparing electrolytes, dyes and standard cell model as per schematic diagram in figure 2 using appropriate materials tools ‘and equipments. Japanese Solar simulator PECCELL model PEC-L01 was used to simulate ‘the solar energy source at 0.1 W m⁻² throughout the study. Readings were recorded soon after setting the cell appropriately for each replicate, within a voltage range of -0.2 to 0.7 V.

ZnO (30 nm) gave the best results with the Polymer Electrolyte and the Dye Indoline D102, with a short circuit current density (Jsc) of 44.5 A m⁻², an open circuit voltage (Voc) of 0.67 V and a fill factor (FF) of ~0.70 resulting in a final overall efficiency (η) of 2.1%.