Dye-sensitized solar cells employing polymers

Dye-sensitized solar cells (DSSCs) are of interest due to their potential use as inexpensive and environmentally friendly photovoltaic (PV) devices with acceptable power conversion efficiency (PCE). Platinum (Pt) metal is, traditionally, the preferred material for the counter electrode (CE) component of DSSCs, however, further development of iodide/triiodide (I−/I3−) based liquid-electrolyte DSSCs using Pt remains challenging due to the high cost of this scarce metal and its susceptibility to corrosion. Additional concerns include solvent leakage and low chemical stability resulting from volatile liquid electrolyte used in DSSCs. In order to counteract this issue, polymer electrolytes or hole-transporters with higher mobilities are employed as a replacement for liquid electrolytes. In this regard, polymers can serve as efficient CE materials by replacing the platinized electrode in liquid-electrolyte DSSCs, while also substituting for the liquid electrolytes as polymer electrolytes or hole-transporters in solid-state or quasi solid-state DSSCs. Considering the fragility and shape restrictions of glass substrates, polymer substrates may also be used to replace rigid glass substrates, providing more flexible DSSCs. Herein, applications of the polymers as cell components (CEs, polymer electrolytes or hole-transporter, and plastic substrates) in DSSCs are discussed, with special focus on the role that polymers play in DSSCs and widely accepted reports of PV performance. The current understanding of the factors and strategies involved in improving the performance of polymers in DSSCs are reviewed and analyzed. In addition, the benefits, challenges and potential utility of polymers for use in DSSCs are assessed.