A significant improvement in the electrocatalytic stability of N-doped graphene nanosheets used as a counter electrode for [Co(bpy)3](3+/2+) based porphyrin-sensitized solar cells

• Published in: ACS applied materials & interfaces 2015-01, Vol.7 (3), p.2116
• Main Authors: Zhai, Peng, Lee, Chih-Chi, Chang, Ya-Huei, Liu, Chang, Wei, Tzu-Chien, Feng, Shien-Ping
• Format: Article
• Language: English
• ISSN: 1944-8252
• DOI: 10.1021/am5083705

A significant improvement in efficiency is achieved for porphyrin (YD2-o-C8) based dye-sensitized solar cells, coupled with [Co(bpy)3](3+/2+) mediator electrolyte. However, the poison of the counter electrode (CE) by the [Co(bpy)3](3+/2+) mediator remains a significant barrier to producing a reliable high-performance device. In this paper, nitrogen-doped graphene nanosheets (NG) are produced using a low-cost solution-based process and are used as the CE for [Co(bpy)3](3+/2+) based porphyrin-sensitized solar cells. These produce significantly better electrocatalytic activity than the commonly used Pt CE. The superior performance is a result of the increased number of catalytic sites and the wettable surface that is caused by the substitution of pyridinic and pyrrolic N into the carbon-conjugated lattice. To the authors' best knowledge, the significantly improved cycling stability (>1000 times) of NG CE for [Co(bpy)3](3+/2+) redox complexes is demonstrated for the first time.