Self assembled monolayers (SAMs) passivation at TiO2/electrolyte interface in dye sensitized solar cell (DSSC)

• Main Author: Tan, Shi Ying.
• Other Authors: Wong Chee Cheong
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Materials::Energy materials
• Online Access: http://hdl.handle.net/10356/38799
• Institution: Nanyang Technological University

Dye-sensitized solar cells are improved by passivation of different types of self-assembled monolayers (SAMs) coating on dyed titanium oxide by reducing the interfacial charge recombination from conduction band to triiodide in the electrolyte. The cells based on nanocrystalline TiO2 have been fabricated by utilizing a ruthenium dye sensitizer [cis-Bis(isothiocyanato)(2,2’-bipyridyl-4,4’-dicarboxylato)(4,4’-di-nonyl-2’-bipyridyl) ruthenium(II)] and octadecylsilanes with different headgroups (C18H37Si(OCH3)3, C18H37SiH3, and C18H37SiCl3) as coating. The performance of devices was evaluated on the basis of their photocurrent-voltage characteristics, Fourier transform infrared (FTIR) spectrum, ultraviolet-visible spectroscopy, and electrochemical impedance spectroscopy. The SAMs of C18H37Si(OCH3)3 and C18H37SiH3 coating on dyed titanium oxide results in a ~ 10% and ~ 20% improvement respectively in device efficiency while C18H37SiCl3 shows a decrease in efficiency. The short circuit current (Isc) and open circuit voltage (Voc) increase as well after SAMs passivation of C18H37Si(OCH3)3 and C18H37SiH3 . These observations are discussed based on the effect and mechanism of this SAMs passivation on dyed titanium oxide.