Nitrogen-Containing Hierarchically Porous Tubular Carbon as an Efficient Counter Electrode for Dye-Sensitized Solar Cells

Nitrogen-containing tubular carbon with hierarchically pore networks is derived by carbonizing and activating polypyrrole nanotubes (APNT), and is utilized as an efficient counter electrode (CE) for dye-sensitized solar cells (DSSCs). APNT exhibits interconnected micro-mesoporous surface (shell) and macroporous tubular structure (core) with large surface area of 636.27 m
²
/g and pore volume of 0.66 cm
³
/g. The APNT CE film shows sheet resistance of 1.02 × 10
³
Ω/sq and conductivity of 71.42 S/m. APNT displays highly enhanced catalytic activity toward triiodide (I
₃
^-
) reduction due to its superior morphological structures, including large surface area and interconnected hierarchical porous core/shells, which assure a fast mass transport. The significant introduction of catalytic defect sites, improved conductivity, and increased graphitic-N state during the activation process also aided the enhanced catalytic activity, and hence, considerably improved its photovoltaic performance. APNT-based DSSC shows power conversion efficiency of 6.29%, that is comparable with standard Pt based DSSC (6.80%).