Hierarchical DSSC structures based on single walled TiO2 nanotube arrays reach back-side illumination solar light conversion efficiency of 8%

TL;DR

This paper presents a method to construct hierarchical DSSC structures using single-walled TiO2 nanotubes, achieving an 8% efficiency under back-side illumination by optimizing electronic properties and dye loading.

Contribution

It introduces a controlled layer-by-layer decoration technique for TiO2 nanotubes, enhancing DSSC efficiency through structural and surface modifications.

Findings

Achieved 8% solar conversion efficiency with the new structure.

Controlled removal of inner shell improves electronic properties.

Layer-by-layer decoration increases dye loading.

Abstract

In the present work we introduce a path to the controlled construction of DSSCs based on hierarchically structured single walled, self-organized TiO2 layers. In a first step we describe a simple approach to selectively remove the inner detrimental shell of anodic TiO2 nanotubes (NTs). This then allows controlled well-defined layer-by-layer decoration of these TiO2-NT walls with TiO2 nanoparticles (this in contrast to conventional TiO2 nanotubes). We show that such defined multiple layered decoration can be optimized to build dye sensitized solar cells that (under back-side illumination conditions) can yield solar light conversion efficiencies in the range of 8 %. The beneficial effects observed can be ascribed to a combination of three factors : 1) improved electronic properties of the single walled tubes themselves, 2) a further improvement of the electronic properties by the defined TiCl4 treatment, and 3) a higher specific dye loading that becomes possible for the layer-by-layer decorated single walled tubes.