Conducting Polymers as Cost Effective Counter Electrode Material in Dye-Sensitized Solar Cells

Abstract

Dye-sensitized solar cells (DSCs) are third generation photovoltaic devices capable of harvesting solar energy to generate electricity. DSCs have gained significant research interest during past decades due to its high theoretical power conversion efficiencies and most importantly the cost effectiveness and environment friendly fabrication process. Firstly, in this chapter, the function of the counter electrode (CE) in a DSC has been discussed in brief. The CE participates in the electron transfer from the external circuit back to the redox mediator thereby catalyzing its regeneration reaction. In the state of art DSCs, Pt has been the preferred CE material. Properties such as promising conductivity and high electrocatalytic activity towards the process of reduction of \( {\text{I}}^{-}_{3} \) to \( {\text{I}}^{-}\) which is the typical redox mediator, contributes to its applicability as the preferred CE material. However, the use of Pt CE adhere major drawbacks such as the high cost and its susceptibility to undergo corrosion. These limitations have emphasized the importance of exploring alternative cost effective functional materials with better conductivity and electrocatalytic properties. Subsequently, the limitations of using Pt as the CE materials, and the advantages and challenges associated with alternative materials have been elaborated. Conducting polymers with extended conjugate electron systems are a promising substitute material for Pt in DSCs. A wide range of conducting polymers and polymer hybrid composites have been investigated for their applicability as CEs in DSCs. These polymers have gained popularity not just due to cost effectiveness compared to Pt but also due to their promising conductivity, superior electrocatalytic properties, easy preparation and fabrication. Different types of conjugated polymers and polymer hybrid composites, their synthetic methods, fabrication processes and their respective photovoltaic performances are then reviewed. Finally, the future prospects of conducting polymers as CE material has been discussed.