Charge Transport Properties of ZnO Nanorod Aggregate Photoelectrodes for DSCs

• Published in: Journal of physical chemistry. C Vol. 115; no. 43; pp. 20992 - 20999
• Main Authors: Park, Kwangsuk, Xi, Junting, Zhang, Qifeng, Cao, Guozhong
• Format: Journal Article
• Language: English
• Published: American Chemical Society 03.11.2011
• Subjects: C: Nanops and Nanostructures
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp2067292

Charge transport properties such as electron lifetime (τn), electron diffusion coefficient (D n), and electron diffusion length (L n) were investigated for the ZnO nanorod aggregate photoelectrodes annealed at different temperatures to understand the effects of structural evolution on the charge transport properties. With an increasing annealing temperature, the ZnO nanorod crystallites in aggregates experienced the structural evolution from individual rods to partially sintered rods and finally spherical large ZnO nanocrystallites, resulting in the appreciable growth of nanocrystallites and the necks between adjacent nanocrystallites and corresponding surface area reduction. Consequently, the charge transport properties in ZnO photoelectrodes were changed accordingly. The charge transport properties like τn, D n, and L n showed a strong dependence on nano- and microstructures of the photoelectrodes. This study on the correlation between sintered structure and charge transport properties shows that controlled thermal annealing affecting both light harvesting efficiency and charge collection efficiency through the structural evolution of the ZnO nanocrystallites could be a critical factor for high performance of dye-sensitized solar cells (DSCs).