In Situ Study of Degradation in P3HT-Titania-Based Solid-State Dye-Sensitized Solar Cells

The degradation of poly(3-hexylthiophene) (P3HT) -titania-based solid-state dye-sensitized solar cells (ssDSSCs) is studied to better understand device aging mechanisms. The correlation of temporal evolution between P3HT crystallite structures and device performance is discussed for the first time using in situ measurements. For comparison, two types of mesoporous titania photoanodes with different pore sizes are prepared. Grazing incidence wide-angle X-ray scattering is used in situ under continuous solar illumination to obtain information about the impact of pore size on P3HT crystalline order and on temporal evolution of the P3HT crystallites. The development of the photovoltaic characteristics is explored in parallel. The lattice constants, crystal sizes, and volume fraction of crystalline P3HT in the large-pore active layer remain stable over 30 min, while the volume fraction of crystalline P3HT decreases in the small-pore active layer. Thus, the pore size of titania photoanodes is important for the stability of P3HT titania-based ssDSSCs.