Hydrothermally Grown TiO Nanorod Array Memristors with Volatile States.

In the present study, the memristive characteristics of hydrothermally grown TiO nanorod arrays, particularly, the difference in the retention time of the resistance state, are investigated in dependence of the array growth temperature. A volatile behavior is observed and related to a redistribution of oxygen vacancies over time. It is shown that the retention time increases for increasing array growth temperatures from several seconds up to 20 min.

Position-controlled laser-induced creation of rutile TiO nanostructures.

For potential applications of nanostructures, control over their position is important. In this report, we introduce two continuous wave laser-based lithography techniques which allow texturing thin TiO films to create a fine rutile TiO structure on silicon via spatially confined oxidation or a solid-liquid-solid phase transition, for initial layers, we use titanium and anatase TiO, respectively. A frequency-doubled Nd:YAG laser at a wavelength of 532 nm is employed for the lithography process and the samples are characterized with scanning electron microscopy.

Advanced scanning probe lithography using anatase-to-rutile transition to create localized TiO nanorods.

In this article, we demonstrate the position-controlled hydrothermal growth of rutile TiO nanorods using a new scanning probe lithography method in which a silicon tip, commonly used for atomic force microscopy, was pulled across an anatase TiO film. This process scratches the film causing tiny anatase TiO nanoparticles to form on the surface. According to previous reports, these anatase particles convert into rutile nanocrystals and provide the growth of rutile TiO nanorods in well-defined areas.

Role of the Metal-Oxide Work Function on Photocurrent Generation in Hybrid Solar Cells.

ZnO is a widely used metal-oxide semiconductor for photovoltaic application. In solar cell heterostructures they not only serve as a charge selective contact, but also act as electron acceptor. Although ZnO offers a suitable interface for exciton dissociation, charge separation efficiencies have stayed rather poor and conceptual differences to organic acceptors are rarely investigated.

Tuning the Electronic Conductivity in Hydrothermally Grown Rutile TiO₂ Nanowires: Effect of Heat Treatment in Different Environments.

Hydrothermally grown rutile TiO₂ nanowires are intrinsically full of lattice defects, especially oxygen vacancies. These vacancies have a significant influence on the structural and electronic properties of the nanowires. In this study, we report a post-growth heat treatment in different environments that allows control of the distribution of these defects inside the nanowire, and thus gives direct access to tuning of the properties of rutile TiO₂ nanowires.

Incoherent Pathways of Charge Separation in Organic and Hybrid Solar Cells.

In this work, we investigate the exciton dissociation dynamics occurring at the donor:acceptor interface in organic and hybrid blends employed in the realization of photovoltaic cells. Fundamental differences in the charge separation process are studied with the organic semiconductor polymer poly(3-hexylthiophene) (P3HT) and either [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) or titanium dioxide (TiO) acting as the acceptor. By using ultrafast broad-band transient absorption spectroscopy with few-fs temporal resolution, we observe that in both cases the incoherent formation of free charges dominates the charge generation process.

Thiophene-Functionalized Hybrid Perovskite Microrods and their Application in Photodetector Devices for Investigating Charge Transport Through Interfaces in Particle-Based Materials.

Particle-based semiconductor materials are promising constituents of future technologies. They are described by unique features resulting from the combination of discrete nanoparticle characteristics and the emergence of cooperative phenomena based on long-range interaction within their superstructure. (Nano)particles of outstanding quality with regards to size and shape can be prepared via colloidal synthesis using appropriate capping agents.

Toward High-Efficiency Solution-Processed Planar Heterojunction SbS Solar Cells.

Low-cost hybrid solar cells have made tremendous steps forward during the past decade owing to the implementation of extremely thin inorganic coatings as absorber layers, typically in combination with organic hole transporters. Using only extremely thin films of these absorbers reduces the requirement of single crystalline high-quality materials and paves the way for low-cost solution processing compatible with roll-to-roll fabrication processes. To date, the most efficient absorber material, except for the recently introduced organic-inorganic lead halide perovskites, has been SbS, which can be implemented in hybrid photovoltaics using a simple chemical bath deposition.