Rational Design of Metal Oxide–Based Cathodes for Efficient Dye‐Sensitized Solar Cells

Abstract

Recently, there is an urgent need for alternative energy resources due to the nonrenewable nature of fossil fuels and the increasing CO 2 greenhouse gas emissions. The photovoltaic technologies which directly utilize the abundant and sustainable solar energy are critical. Among various photovoltaic devices (solar cells), dye-sensitized solar cells (DSSCs) have gained increasing attention due to their high efficiency and easy fabrication process in the past decade. The cathode is a critical part in DSSCs while the benchmark Pt cathode suffers from high cost and scarcity. Thus, the development of alternative Pt-free cathodes have attracted numerous attentions to heighten the cost competitiveness of DSSCs. Among various cathodes, metal oxides are of growing interest due to their superior activity, robust stability and low cost. Simple oxides such as WO 3 and SnO 2 are used as cathodes for DSSCs. Considering the fixed atomic environment in simple oxides, complex oxides are more attractive as cathodes because of their more flexible physical and chemical properties. This review attempts to present the rational design of simple/complex metal oxide-based cathodes in DSSCs and then to provide useful guidance for the future design and development of Pt-free cathodes. The demonstrated design strategies can be extended to other electrocatalysis-based applications.Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff))

Fundamental Understanding of Photocurrent Hysteresis in Perovskite Solar Cells

“…Moreover, some efforts have been devoted to improving the electrocatalytic activity of the photocathode to efficiently reduce the oxidized electrolyte. Thus, in addition to conventional Pt, some novel materials including carbon materials [36] , perovskite oxides [37,38] , metal nitrides [39] and nanostructured composite materials [40] have been investigated as promising photocathode alternatives in DSSCs.…”

An Intrinsically Conductive Phosphorus‐Doped Perovskite Oxide as a New Cathode for High‐Performance Dye‐Sensitized Solar Cells by Providing Internal Conducting Pathways

“…It indicates that the commercial MWCNTs without any special treatment should not be a high‐performance electrocatalyst for IRR. The combination of perovskite and carbon material greatly enhanced the IRR activity as compared with the individual component, which can be assigned to the fact that perovskite oxide provided the active sites for IRR and the carbon material served as a highly conductive substrate as demonstrated in our previous study …”

“…The combination of perovskite and carbon material greatly enhanced the IRR activity as compared with the individual component, which can be assigned to the fact that perovskite oxide provided the active sites for IRR and the carbon material served as a highly conductive substrate as demonstrated in our previous study. [17,31] The IRR activity of the cathode in DSSCs is indicated by PCE and FF, which are important parameters to describe the IRR process. FF was reported to be very relevant to the conductivity of the cathode, and a higher conductivity generally leads to a larger FF value.…”

“…However, Pt suffers from several drawbacks such as low abundance, high price, and poor stability in the electrolyte. Consequently, tremendous efforts have been made to develop low‐cost, highly active, and stable Pt‐free cathodes …”

“…Consequently, tremendous efforts have been made to develop low-cost, highly active, and stable Pt-free cathodes. [16][17][18][19][20] Perovskite oxides (ABO 3 ) have emerged as an important family of functional materials based on their low-cost and earth-abundant constituent elements. [21,22] Compared with other types of metal oxides, a major superiority of perovskite oxides is their compositional and structural flexibility.…”