Enhancing photovoltaic performance of dye-sensitized solar cells through TiO2/g-C3N4 nanocomposite photoanodes for improved charge carrier management

Abstract

This study explores the enhancement of dye-sensitized solar cells (DSSCs) through the modification of porous TiO₂ photoanodes by incorporating two-dimensional graphitic carbon nitride (g-C₃N₄) synthesized from urea. The combination of wide-bandgap TiO₂ with narrow-bandgap g-C₃N₄ extends the optical response range of the TiO₂ heterostructure composites from ultraviolet to visible light. The introduction of g-C₃N₄ with TiO₂ to form a heterojunction significantly boosts the photovoltaic performance of the device by minimizing charge recombination at the photoanode-electrolyte interface. Upon optimizing the g-C₃N₄ loading, a peak power conversion efficiency (PCE) of 10.79 % is achieved, representing an impressive 42 % improvement over the pristine TiO₂-based device. This enhancement is primarily attributed to the efficient separation of photogenerated charge carriers, facilitated by the type II band alignment between g-C₃N₄ and TiO₂. This alignment, enabled by favorable conduction and valence band offsets, accelerates the separation of photogenerated carriers and prolongs electron lifetime.