Analysis on growth mechanism of TiO2 nanorod structures on FTO glass in hydrothermal process

Illustration of the growth mechanism of TiO2 nanorods during hydrothermal process with a new approach from the crystallization and deposition of precursors in solution. [Display omitted] Understanding the growth mechanism of TiO2 nanorods (TNRs) is critical for producing high-performance materials with morphology and structure control. TNRs on FTO glass were prepared by hydrothermal method in acidic solution. The structural and morphological characteristics of thin films were investigated for different temperatures and reaction times. By the hydrolysis and protonation, monomers Ti(OH)n(OH2)6-n](4-n)+ can be formed at ambient conditions. TNRs were formed through the bonding between these monomers by olation and oxolation reactions during hydrothermal process. During the hydrothermal growth of TNRs on FTO glass, precursors of TNRs and nanoflowers were observed in the reactive solution and on top of TNR thin films. The preferential deposition of precursors and TiO2 nanostructures on top of primary TNRs from solution resulted in significant changes in their morphology, structure, and growth orientation. A new possible growth mechanism of TNRs is proposed based on these experimental observations. Our preliminary results show positive signs to apply the prepared TNRs as electron transfer layer of perovskite solar cells (PSCs). This study will become the basis for our further researches to apply the prepared TNR thin films with the most suitable structural and morphological properties to high-performance PSCs as well as other photovoltaic devices.