Transmittance Enhanced Properties of Novel Encapsulated ITO/Arc-TiO2 Antireflective TCO Substrate Prepared by RF Magnetron Sputtering

In this work, a thermally stable multilayered transparent conducting oxide (TCO) utilizing TiO2 antireflection thin film (arc-TiO2) encapsulated under indium tin oxide (ITO) glass has been prepared by RF magnetron sputtering. The novel tri-functional conducting substrate with blocking layer capabilities has been designed via step-down interference coating structure of double layer antireflection coating (DLAR). The mixed-oriented type between the strongest ITO peak at (222) and a weak TiO2 peaks at (101) orientations have been observed under XRD analysis. The antireflection properties of double-layer ITO/arc-TiO2 is evidence with the existence of two maximum peaks around 410 nm and 750 nm. While, the corresponding reduction in reflectance of about 8% and 2% compared to bare ITO was achieved. The ITO/arc-TiO2 blocking layers conserves the low resistivity of ITO at 2.05 x 10-4 Ω cm, even after oxidizing during air annealing process above 400 °C. These results demonstrate that the multilayered ITO/arc-TiO2 with tailored refractive index by means of annealing treatment is a promising approach to realize a substrate which (a): electrically and thermally stable against processing temperature, (b): sustains the higher transmittance of the substrate even there is increase in total substrate thickness and (c): prevents electron recombination process occurring at the interface between the redox electrolytes and the TCO surface. The stable properties are found to be beneficial for use as TCOs in DSSCs.