1. Introduction
Dye-sensitized solar cell (DSSC) has emerged as one of the representative photovoltaic technology for next generation, of which working mechanism resemble the principle of photosynthesis process in nature.1-7 In DSSC, the most popular component of counter electrode (CE) is platinum (Pt) based thin film on F-doped SnO (FTO) conducting glass because of its high electrochemical activity.8,9 However, in addition to the high cost of Pt that prevent the materials from large scale applications, I3-/I- electrolyte is corrosive towards Pt during its long-term operation, which hamper the commercial success of DSSCs.1,10 In order to replace Pt with more chemically stable materials, CEs based on carbon materials have been investigated, producing low-cost solar cells with reasonable performances.11-24 Among carbon materials, graphene or graphene oxide (GO) is a prospective alternative to the Pt CE for DSSC due to its high electron mobility and low cost as demonstrated in previous literatures.25-35 However, solar energy conversion efficiencies of such examples are often limited probably due to high but not enough catalytic activities of GO layer. Since Pt has been well known to provide an exceptionally high catalytic activity as an essential component of photocathode in DSSC, hybridization of Pt with such carbon materials may afford optimum combination for DSSC. Actually, many examples on such efforts can be found in literatures,36,37 especially Pt/carbon nanotube hybrids.38,39 Recently, Pt/reduced graphene oxide (rGO) hybrid CEs start to appear in literatures,40-44 reporting that a CE employing graphene/Pt composite is a promising alternative to the conventional Pt CE in terms of energy conversion efficiency and Pt-saving low cost devices. However, in most cases, the photovoltaic performances and the complex fabrication processes of the graphene/Pt CE reported so far remain large room to be improved. Here we report a simple and scalable fabrication process to afford Pt/rGO hybrid CE, having high transparency and excellent electrocatalytic activity, through sequential spin coating and concurrent thermal reduction of the components. The photovoltaic performances and characteristics of the corresponding DSSCs are also investigated.
1. บทนำDye-sensitized solar cell (DSSC) has emerged as one of the representative photovoltaic technology for next generation, of which working mechanism resemble the principle of photosynthesis process in nature.1-7 In DSSC, the most popular component of counter electrode (CE) is platinum (Pt) based thin film on F-doped SnO (FTO) conducting glass because of its high electrochemical activity.8,9 However, in addition to the high cost of Pt that prevent the materials from large scale applications, I3-/I- electrolyte is corrosive towards Pt during its long-term operation, which hamper the commercial success of DSSCs.1,10 In order to replace Pt with more chemically stable materials, CEs based on carbon materials have been investigated, producing low-cost solar cells with reasonable performances.11-24 Among carbon materials, graphene or graphene oxide (GO) is a prospective alternative to the Pt CE for DSSC due to its high electron mobility and low cost as demonstrated in previous literatures.25-35 However, solar energy conversion efficiencies of such examples are often limited probably due to high but not enough catalytic activities of GO layer. Since Pt has been well known to provide an exceptionally high catalytic activity as an essential component of photocathode in DSSC, hybridization of Pt with such carbon materials may afford optimum combination for DSSC. Actually, many examples on such efforts can be found in literatures,36,37 especially Pt/carbon nanotube hybrids.38,39 Recently, Pt/reduced graphene oxide (rGO) hybrid CEs start to appear in literatures,40-44 reporting that a CE employing graphene/Pt composite is a promising alternative to the conventional Pt CE in terms of energy conversion efficiency and Pt-saving low cost devices. However, in most cases, the photovoltaic performances and the complex fabrication processes of the graphene/Pt CE reported so far remain large room to be improved. Here we report a simple and scalable fabrication process to afford Pt/rGO hybrid CE, having high transparency and excellent electrocatalytic activity, through sequential spin coating and concurrent thermal reduction of the components. The photovoltaic performances and characteristics of the corresponding DSSCs are also investigated.
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