Synthesis, surface properties, crystal structure and dye sensitized solar cell performance of TiO2 nanotube arrays anodized under different voltages

• Published in: Vacuum 2017-10, Vol.144, p.183-189
• Main Authors: Bozkurt Çırak, Burcu, Karadeniz, Sibel Morkoç, Kılınç, Tuba, Caglar, Bulent, Ekinci, Ali Ercan, Yelgin, Hüseyin, Kürekçi, Mehmet, Çırak, Çağrı
• Format: Article
• Language: English
• Subjects: Anodization voltage; Contact angle; Dye sensitized solar cells; Elastic modulus; Roughness; TiO2 nanotubes
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2017.07.037

In this study, anodic TiO2 nanotube (TNT) arrays with average nanotube diameter from 26 nm to 115 nm and length from 1.3 μm to 6.4 μm were grown by electrochemical method. Anodization process were performed under different voltages from 10 to 50 V in ethylene glycol – ammonium fluoride – water electrolyte. Formation mechanism of TNTs was summarized. Surface morphology, crystal structure, roughness, wettability and elasticity of TNT arrays were characterized by using field emission scanning electron microscope (FESEM), X-Ray diffraction (XRD), atomic force microscope (AFM), optical tensiometer and universal mechanical tester, respectively. Water contact angle measurements and nanoindentation tests proved that water contact angle and elastic modulus of TNT arrays decrease with increasing anodization voltage. Photocurrent-photovoltage curves and electrochemical impedance spectroscopy (EIS) measurements of dye sensitized solar cells (DSSC) were made to investigate the effects of anodization voltages on photoanode performance. The light conversion efficiency and photocurrent density of TNT photoanodes was increased with increasing anodization voltage due to larger nanotube length and surface area. The results show that anodization voltage is significant parameter for the surface properties and dye sensitized solar cell (DSSC) performance TNT arrays. •TiO2 nanotube arrays were grown under anodization voltages from 10 to 50 V.•Effect of anodization voltage on crystal structure, morphology, roughness, wettability and elastic modulus were investigated.•Enhanced DSSC performance was observed with increasing anodization voltage.•RCT1 resistance at WE/Electrolyte interface in DSSC was decreased with increasing anodization voltage.