Poly(3,4-ethylenedioxythiophene) in dye-sensitized solar cells: toward solid-state and platinum-free photovoltaics

Dye-sensitized solar cells (DSSCs) have become a strong reality in the field of hybrid photovoltaics. Their ability to operate in diffused light conditions and the possibility of fabrication of modules bearing different colors make these cells attractive for different applications, for example, wearable electronics, building integration, etc. This review focuses on one of the compounds rather often studied for DSSCs, namely, poly(3,4-ethylenedioxythiophene) (PEDOT). It has been introduced both as a substitute for liquid electrolytes, in order to facilitate cells fabrication and increase their durability, and as an alternative to platinum for counter electrodes. The literature counts many studies on PEDOT and this manuscript collects them following a classification criterion based on applications, functionalization/doping strategies, and deposition methods. In addition to comparing the performance obtained for PEDOT-based systems with those of traditional cells (i.e., assembled with liquid iodine-based electrolytes and platinum cathodes), the manuscript also offers a brief analysis of costs and sustainability aspects, built up on experimental data found in the literature; this latter is expected to constitute a precious resource to catalyze the attention of the scientific community on relevant and preliminary aspects when figuring out the industrial scalability of newly proposed cell components.