Thermal impact on (001) faceted anatase TiO2 microtablets and nanowalls's lattices and its effect on the photon to current conversion efficiency

• Published in: The Journal of physics and chemistry of solids Vol. 127; pp. 213 - 223
• Main Authors: Dahlan, Dahyunir, Ramli, Muhamad Adam, Fiqrian, Khudbatul, Md Saad, Siti Khatijah, Oyama, Munetaka, Umar, Akrajas Ali
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-04-2019
• Subjects: DSSCs; faceted anatase TiO2; Microtablet; Nanowalls; Photoactivity; Thermal impact; Nanowalls; DSSCs; Microtablet; faceted anatase TiO2; Thermal impact; Photoactivity
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/j.jpcs.2018.12.026

Thermal annealing impact on the properties of (001) faceted anatase TiO2 with two different morphologies, i.e. microtablet (TMT) and nanowall (TNW), have been examined by observing the change in their lattice paramaters and photovoltaic properties when being subjected to several thermal annealing intervals, i.e. from 1 to 7 h, at 450 °C, under ambient atmosphere. The TMT and TNW were prepared on ITO substrate via liquid phase deposition method. The TMT is characterized by a squared tablet-like shape meanwhile the TNW is a squared-platelet morphology nanostructures. The XRD and Raman analysis indicated that both TMT and TNW underwent a lattice expansion with the increasing of the annealing interval. For example, the Raman results indicates that the main Raman character of Eg, i.e. OTiO bridge bending oscilation, as well as B1g and A1g, i.e. TiO strain oscilation, blue-shifted with the increasing of the thermal annealing duration. However, the expansion is approximately 1.4% higher in TNW compared to TMT. Regarding the surface chemistry activity, it is higher on the TNW and it increases with the increasing of thermal annealing impact. Meanwhile, the TMT showed a tendency to steadily decrease in its surface chemistry activity with the increasing of the thermal annealing impact. The modification in the lattice parameters and the surface chemistry activity have effectively modified the TMT and TNW's photovoltaic performance. In typical process, the power conversion efficiency improve from 1.8% to 3.2% for DSSCs utilizing TMT and 1.5%–3.0% in TNW when the thermal annealing impact was increased. In general, the TNW exhibits relatively higher electrical and optical properties stability compared to TMT that is indicated by a small variation in the PCE value when the thermal impact further increased up to almost double above the optimum condition.
Thermal impact (annealing time) creates different responses on anatase TiO2 with two different morphologies, enhancing their electrical and optical properties for high-performance DSSCs applications. [Display omitted]
•Thermal impact produces different response in (001) faceted anatase TiO2 with different morphology.•Lattice expansion is higher for almost 1.4% in nanowalls than the microtablet.•Lattice refinement has improved the photovoltaic performance of DSSCs utilizing microtablet and nanowals.