Adapting Ruthenium Sensitizers to Cobalt Electrolyte Systems.
In this work, we report the use of bulky substitutions in a new heteroleptic ruthenium(II) bipyridine complex, Ru(NCS)2LL', coded TT-230 to obtain high open-circuit potential in a dye-sensitized solar cell (where L is a bipyridine ligand appended with two cyclopenta(2,1-b;3,4-bA)dithiophene moieties, and L' = 4,4,'-dicarboxylic acid 2,2'-bipyridine). The electrolytes based on cobalt complexes have shown significant advantages in terms of attainable open-circuit potential compared to the standard iodide/tri-iodide redox mediators. These merits of the cobalt complexes were previously realized with a porphyrin sensitizer, achieving a VOC greater than 1 V in DSC. However, with conventional Ru(II)-polypyridyl complexes such as the C101 dye, similar increase in the VOC could not be attained due to the enhanced recombination. In this work, we have shown that the use of bulky substituents can prevent the back reaction of photogenerated electron and subsequently increase the open-circuit potential of the device. The recombination processes were investigated by transient photovoltage decay measurements.
†Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology (EPFL), Station 6, CH 1015 - Lausanne, Switzerland.|∥Ion Adsorption Lab, Department of Chemical Engineering, Indian Institute of Technology at Delhi, Hauz Khas, New Delhi - 110016, India.
Sangeeta
S
Amit Kumar
‡Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.|§Instituto Madrileño de Estudios Avanzados (IMDEA)-Nanociencia, c/Faraday, 9, Cantoblanco, 28049 Madrid, Spain.
Maxence
M
Urbani
‡Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
María
M
Medel
†Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology (EPFL), Station 6, CH 1015 - Lausanne, Switzerland.|‡Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
Mine
M
Ince
‡Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
David
D
González-Rodríguez
†Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology (EPFL), Station 6, CH 1015 - Lausanne, Switzerland.
Aravind Kumar
AK
Chandiran
∥Ion Adsorption Lab, Department of Chemical Engineering, Indian Institute of Technology at Delhi, Hauz Khas, New Delhi - 110016, India.
Ashok N
AN
Bhaskarwar
‡Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.|§Instituto Madrileño de Estudios Avanzados (IMDEA)-Nanociencia, c/Faraday, 9, Cantoblanco, 28049 Madrid, Spain.
Tomás
T
Torres
†Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology (EPFL), Station 6, CH 1015 - Lausanne, Switzerland.
Md K
MK
Nazeeruddin
†Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology (EPFL), Station 6, CH 1015 - Lausanne, Switzerland.
Michael
M
Grätzel
Cyclopentadithiophene; cobalt complexes; dye-sensitized solar cells; redox shuttles; ruthenium dyes