Synthesis and Properties of New Polypyridyl Ruthenium Complexes and Their Application for Dye-sensitized Solar Cells
Date Issued
2010
Date
2010
Author(s)
Hung, Chun-Yi
Abstract
This thesis is to investigate the properties, adsorption behavior, nanostructure and photovoltaic performance of Ru(4,4’-dicarboxylic acid) (4-nonyl- 2,2’- bipyridine)-(NCS)2 denoted as Ru-C9, Ru(4,4’-dicarboxylic acid)(4,4’-dimethyl-2,2’-bipyridine)-(NCS)2 denoted as Ru-2A ,and Ru(4-carboxylic acid-4’-Methyl) (4,4’-dimethyl-2,2’-bipyridine)-(NCS)2 denoted as Ru-1A.
In the first part, we compared the complexes with different numbers of aliphatic side chains, (NaRu(4,4’-dicarboxylic acid)(4,4’- dinonyl- 2,2’- bipyridine)-(NCS)2) denoted as Z907Na, (Ru(4,4’-dicarboxylic acid)(4,4’- dinonyl- 2,2’- bipyridine) -(NCS)2) denoted as Z907and RuC9. Z907Na, Z907 and Ru-C9 were characterized by NMR and FTIR, and their optical property in acetonitrile/tert-butanol was studied by UV-Vis absorption spectroscopy. Then, we investigated the photovoltaic performance of Z907Na, Z907 and Ru-C9 in DSSCs with a methoxypropionitrile liquid type electrolyte and gave conversion efficient of 6.92%, 6.54 % and 6.80% individually. By using electrochemical impedance spectroscopy (EIS), Z907Na and Z907 showed longer electron life time but higher resistance than Ru-C9 due to more aliphatic side chains.
The adsorption mechanism of ruthenium dyes were studied by AFM, TEM and DLS. The results revealed that the adsorption of dye molecules onto TiO2 surface began in micelle form and followed by the dissolution of the condensed dyes located away from TiO2. Increasing the time of adsorption leaded to a homogeneously dye-covered surface. Then, we measured the adsorptive amount of Z907Na, Z907 and Ru-C9 on the TiO2 at different adsorbing time interval with UV-vis absorption spectroscopy. After 12 h adsorption, the adsorptive amount of the three complexes reached saturation. And the TiO2 surface is covered by a monolayer of dye.
In the second part, we synthesized Ru2A and Ru1A with different numbers of carboxylic acid groups which were compared with the commercial N3 in the photovoltaic performance. The two complexes were also characterized by NMR and FTIR and their optical property in acetonitrile/tert-butanol were measured by UV-Vis absorption spectroscopy. For the performance of DSSCs, Ru-2A, Ru1A and N3 with methoxypropionitrile liquid electrolyte attained power conversion efficiency 7.02 %, 3.39 %, and 7.82 % respectively. Then, we used EIS, intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) to measure the electron life time and charge collection efficiency. With increasing the numbers of carboxylic acid groups on the Ru complex, the electron life time was longer and charge collection efficiency was higher.
The adsorption mechanism of ruthenium complexes were studied by AFM, TEM and DLS. Ru-2A, Ru-1A and N3 molecules quickly adsorbed onto the TiO2 surface, leading to a homogeneous surface with an approximate height of one dye molecule. We measured the adsorptive amount of Ru2A, Ru1A and N3 on the TiO2 at different adsorbing time interval with UV-vis absorption spectrascopy. Through calculation, we suggested that Ru-2A after 6 h adsorption covered a monolayer with the molecules tilted near vertically with respect to the TiO2 surface. Due to that N3 had four carboxylic acid groups, it easily lied in flat form on the surface of TiO2. This is the reason why the surface of N3 is larger than Ru-2A. The adsorptive amount of N3 on TiO2 surface reached a monolayer within 24 h. Because the N3 molecules tended to interact each other with their carboxylic acid groups, the adsorption might be more than mono layer. Because Ru-1A has only on carboxylic group which was adsorbed to TiO2 in more versatile configuration, the surface area of Ru-1A was in between those of Ru-2A and N3.
Subjects
Dye sensitized solar cells
short current
open circuit voltage
SDGs
Type
thesis
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