The optimization of Titanium Dioxide (TiO₂) thickness and organic dye sensitizers to improve dye sensitized solar cell (DSSC) performance

Renewable energy especially solar energy has attracted much attention due to its features which provides free energy by converting sunlight into electrical energy without harming the environment. Silicon based solar cell has pioneered the photovoltaic market due to its potential in converting more radiance of the sun into electrical energy thus having high conversion efficiency and by far, is a reliable mechanism in light harvesting. Despite having all odds in its favor, a typical silicon based photovoltaic is produced and sold at high cost due to its tedious production step and this is when dye sensitized solar cell (DSSC) has been introduced in 1991 by Micheal Gratzel and Brian O’Regan. DSSC promises an easy and low cost of manufacturing process at which can also operate in low light condition. DSSC uses ruthenium (Ru) based dyes compound which provides relatively high efficiency of 11.1%, yet, there are several drawbacks on the use of Ru complexes such as limited amount of noble metals, high cost and sophisticated synthesis steps. To address this issue, metal-free organic dyes have been prepared and applied in DSSC to replace Ru (II) based dyes. This thesis introduces the uses of 15 types of nature based dyes and different thickness of 5 μm and 10 μm of titanium dioxide (TiO₂) film to improve the performance of DSSC. DSSC were assembled using ten types of single dyes extracted from blueberry, dragon fruit, purple cabbage, hibiscus, bougainvillea, coffee, turmeric, blue pea’s flower and morning glory’s flower as well as five types of cocktail dye from the combination of two natural dyes consist of blueberry and bougainvillea, coffee and turmeric, purple cabbage and blueberry, blueberry and dragon fruit and finally morning glory’s flower and purple cabbage.