Photovoltaic stability of dye-sensitized solar cells with carbon paper counter-electrodes

Abstract

Carbon-based counter-electrodes (CEs) offer a cost-effective and environmentally friendly alternative for dye-sensitized solar cells (DSSCs), despite challenges with low intrinsic electrocatalytic activity and poor mechanical stability. This study investigates the use of commercial carbon paper (Sigracet (R) 22BB) as a robust solution, demonstrating that a simple 500 degrees C air-annealing treatment significantly enhances its performance as a CE. A comprehensive characterization that included thermal analyses, morphology, textural properties, photovoltaic response and spectroscopy characterization revealed that the air-annealing process induced sp-hybridized carbon rearrangement, which enhance charge-transfer kinetics and catalytic activity. As a result, a sandwich-configuration iodide-based DSSCs that employed air-annealed carbon paper CE achieved a power conversion efficiency (1PCE) of 8.95 %, closely matching the 9.19 % of a platinum CE reference. Critically, the carbon paper air-annealed-based device exhibited superior long-term stability, retaining a higher 1PCE than platinum-based after 500 h of accelerated aging (6.06 % vs. 5.01 %), a finding attributed to the material's stable and enhanced intrinsic catalytic properties. Furthermore, the robustness of the air-annealed carbon paper enabled its successful implementation in a simplified, spacer-free monolithic architecture, which achieved a competitive 1PCE of 7.60 %. These results highlight carbon paper as a competitive, reusable and stable CE alternative to platinum for DSSCs.