351 research outputs found
Hierarchical DSSC structures based on single walled TiO2 nanotube arrays reach back-side illumination solar light conversion efficiency of 8%
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.Comment: arXiv admin note: text overlap with arXiv:1610.0643
Aligned metal oxide nanotube arrays: key-aspects of anodic TiO2 nanotube formation and properties
Over the past ten years, self-aligned TiO2 nanotubes have attracted
tremendous scientific and technological interest due to their anticipated
impact on energy conversion, environment remediation and biocompatibility. In
the present manuscript, we review fundamental principles that govern the
self-organized initiation of anodic TiO2 nanotubes. We start with the
fundamental question: Why is self-organization taking place? We illustrate the
inherent key mechanistic aspects that lead to tube growth in various different
morphologies, such as rippled-walled tubes, smooth tubes, stacks and
bamboo-type tubes, and importantly the formation of double-walled TiO2
nanotubes versus single-walled tubes, and the drastic difference in their
physical and chemical properties. We show how both double- and single-walled
tube layers can be detached from the metallic substrate and exploited for the
preparation of robust self-standing membranes. Finally, we show how by
selecting the right growth approach to TiO2 nanotubes specific functional
features can be significantly improved, e.g., an enhanced electron mobility,
intrinsic doping, or crystallization into pure anatase at extremely high
temperatures can be achieved. This in turn can be exploited in constructing
high performance devices based on anodic TiO2 in a wide range of applications.Comment: from Nanoscale Horiz., 2016, Advance Articl
Aminated TiO2 nanotube as a Photoelectrochemical Water Splitting photoanode
The present work reports on the enhancement of TiO2 nanotubes
photoelectrochemical water splitting rate by decorating the nanostructure with
an amine layer in a hydrothermal process using diethylenetriamine (DETA). The
aminate coated TiO2 tubes show a stable improvement of the photoresponse in
both UV and visible light spectrum and under hydrothermal conditions, 4-fold
increase of the photoelectrochemical water splitting rate is observed. From
intensity modulated photocurrent spectroscopy (IMPS) measurements significantly
faster electron transport times are observed indicating a surface passivating
effect of the N-decoration.Comment: In Catalysis Today, Available online 21 July 201
Conical-Shaped Titania Nanotubes for Optimized Light Management in DSSCs Reach Back-side Illumination Efficiencies > 8%
In the present work, we introduce the anodic growth of conical shaped TiO2
nanotube arrays. These titania nanocones provide a scaffold for dye-sensitized
solar cell (DSSC) structures with significantly improved photon management,
providing an optimized absorption profile compared with conventional
cylindrical nanotube arrays. Finite difference time domain (FDTD) modelling
demonstrates a drastically changed power-absorption characteristic over the
tube length. When used in a back-side illumination DSSC configuration, nanocone
structures can reach over 60 % higher solar cell conversion efficiency than
conventional tubes. The resulting {\eta} of ca. 8 % represents one of the
highest reported values for Graetzel type DSSCs used under back-side
illumination
- …