Broadband light confinement using a hierarchically structured TiO2 multi-layer for dye-sensitized solar cells

Abstract

Herein, we present a simple strategy for broadband light confinement without sacrificing dye-loading capacity by suitably combining multi-layer architecture with hierarchically structured TiO₂. For this purpose, three distinct TiO₂ hierarchical nanomaterials were exploited to simultaneously realize high internal surface area and a graded series of optical properties (in terms of reflectance and transmittance). The present hierarchically structured multi-layer showed a remarkable improvement in the overall efficiency for dye-sensitized solar cells (DSCs): a maximum of 11.43% at 1 Sun (12.16% at 1/8 Sun) versus 8.15% at 1 Sun (8.26% at 1/8 Sun) for the reference cell made of a nanocrystalline TiO₂ single-layer. This notable result is attributed to the synergetic effects of the enhanced broadband light confinement, dye-loading, and charge-collection efficiency.