Hierarchical DSSC structures based on “single walled” TiO 2 nanotube arrays reach a back-side illumination solar light conversion efficiency of 8

• Published in: Energy & environmental science Vol. 8; no. 3; pp. 849 - 854
• Main Authors: So, Seulgi, Hwang, Imgon, Schmuki, Patrik
• Format: Journal Article
• Language: English
• Published: 2015
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/C4EE03729D

In the present work we introduce a path to the controlled construction of DSSCs based on hierarchically structured single walled, self-organized TiO 2 layers. In a first step we describe a simple approach to selectively remove the inner detrimental shell of anodic TiO 2 nanotubes (NTs). This then allows controlled well-defined layer-by-layer decoration of these TiO 2 -NT walls with TiO 2 nanoparticles (in contrast to conventional TiO 2 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 to the extent 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 TiCl 4 treatment, and (3) a higher specific dye loading that becomes possible for the layer-by-layer decorated single walled tubes.