Vrakatseli Vasiliki E, Kalarakis Alexandros N, Kalampounias Angelos G, Amanatides Eleftherios K, Mataras Dimitrios S
Department of Chemical Engineering, University of Patras, GR-26504 Patras, Greece.
Department of Mechanical Engineering, Technological-Educational Institute of Western Greece, GR-26334 Patras, Greece.
Micromachines (Basel). 2018 Aug 4;9(8):389. doi: 10.3390/mi9080389.
Crystalline TiO₂ films were prepared on unheated glass substrates by radio frequency (RF) reactive magnetron sputtering at normal angle of incidence ( = 0°) and at glancing angle ( = 87°). The effect of the glancing angle on the structure, microstructure, and wetting properties of the films was investigated. The inclination of the substrate led to phase transformation of the deposited films from rutile to either rutile/anatase or anatase, depending on the working pressure. Extreme shadowing at 87° results in a remarkable increase of the films' porosity and surface roughness. The mechanism of the glancing-angle-induced crystalline phase formation is thoroughly discussed based on the thermodynamic, kinetic, and geometrical aspects of the nucleation and is related with the microstructural changes. Both crystalline phase and microstructure significantly affect the wetting properties of the TiO₂ films. Glancing-angle-deposited anatase TiO₂ exhibits a high degree of porosity and roughness, a high rate of UV-induced wettability conversion, and a long-term highly hydrophilic nature in dark. Therefore, anatase TiO₂ is potentially a good candidate for applications as dye-sensitized solar cells (DSSC)/perovskite solar cells, microfluidic devices, and self-cleaning surfaces prepared on thermosensitive substrates.
通过射频（RF）反应磁控溅射，在入射角为正常角度（= 0°）和掠射角（= 87°）的条件下，在未加热的玻璃基板上制备了结晶TiO₂薄膜。研究了掠射角对薄膜结构、微观结构和润湿性的影响。基板的倾斜导致沉积薄膜根据工作压力从金红石相转变为金红石/锐钛矿相或锐钛矿相。87°时的极端阴影导致薄膜孔隙率和表面粗糙度显著增加。基于成核的热力学、动力学和几何方面，深入讨论了掠射角诱导结晶相形成的机制，并与微观结构变化相关。结晶相和微观结构都显著影响TiO₂薄膜的润湿性。掠射角沉积的锐钛矿TiO₂具有高度的孔隙率和粗糙度、高的紫外线诱导润湿性转换率以及在黑暗中长期的高亲水性。因此，锐钛矿TiO₂有可能成为用于染料敏化太阳能电池（DSSC）/钙钛矿太阳能电池、微流控装置以及在热敏基板上制备的自清洁表面等应用的良好候选材料。
