Hierarchical construction of self-standing anodized titania nanotube arrays and nanoparticles for efficient and cost-effective front-illuminated dye-sensitized solar cells

We report on the influence of hierarchical structures, constructed via layer-by-layer assembly of self-standing titania nanotube arrays and nanoparticles, upon charge recombination and photoelectric performance of front-illuminated dye-sensitized solar cells. Both nanotubes and nanoparticles were produced by anodization rather than additionally employing other methods, providing low cost and great simplicity. Electrochemical impedance spectroscopy under AM 1.5 illumination indicates the construction of hybrid morphology has superior recombination characteristics and a longer electron lifetime than nanoparticulate systems. This enhancement with the incorporation of anodized titania nanoparticles with 1D architectures is unprecedented for solar cells. Owing to the better light harvesting efficiency, extended electron lifetime and desirable electron extraction, the short-circuit photocurrent density of solar cell is 18.89 mA cm^-2 with an overall power conversion efficiency of 8.80% and an incident photon-to-current conversion efficiency of 84.6% providing a very promising candidate for sustainable energy production with a high performance/cost ratio.