Molecular layer deposition (MLD) of hybrid organic-inorganic thin films called "titanicones" was achieved using tetrakisdimethylaminotitanium (TDMAT) and glycerol (GL) or ethylene glycol (EG) as precursors. For EG, in situ ellipsometry revealed that the film growth initiates, but terminates after only 5 to 10 cycles, probably because both hydroxyls react with the surface. GL has a third hydroxyl group, and in that case steady state growth could be achieved. The GL process displayed self-limiting reactions for both reactants in the temperature range from 80°C to 160°C, with growth rates of 0.9 to 0.2 Å per cycle, respectively. Infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed the hybrid nature of the films, with a carbon atomic concentration of about 20%. From X-ray reflectivity, the density was estimated at 2.2 g cm(-3). A series of films was subjected to water etching and annealing under air or He atmosphere at 500°C. The carbon content of the films was monitored with FTIR and XPS. Almost all carbon was removed from the air annealed and water treated films. The He annealed samples however retained their carbon content. Ellipsometric porosimetry (EP) showed 20% porosity in the water etched samples, but no porosity in the annealed samples. Electrochemical measurements revealed lithium ion activity during cyclic voltammetry in all treated films, while the as-deposited film was inactive. With increasing charge current, the He annealed samples outperformed amorphous and anatase TiO2 references in terms of capacity retention.

Solar hydrogen devices combine the power of photovoltaics and water electrolysis to produce hydrogen in a hybrid form of energy production. To engineer these into integrated devices (i.e. a water splitting catalyst on top of a PV element), the need exists for thin film catalysts that are both transparent for solar light and efficient in water splitting. Manganese oxides have already been shown to exhibit good water splitting performance, which can be further enhanced by conformal coating on high surface-area structures. The latter can be achieved by atomic layer deposition (ALD). However, to optimize the catalytic and transparency properties of the water splitting layer, an excellent control over the oxidation state of the manganese in the film is required. So far MnO, Mn3O4 and MnO2 ALD have been shown, while Mn2O3 is the most promising catalyst. Therefore, we investigated the post-deposition oxidation and reduction of MnO and MnO2 ALD films, and derived strategies to achieve every phase in the MnO-MnO2 range by tuning the ALD process and post-ALD annealing conditions. Thin film Mn2O3 is obtained by thermal reduction of ALD MnO2, without the need for oxidative high temperature treatments. The obtained Mn2O3 is examined for solar water splitting devices, and compared to the as-deposited MnO2. Both thin films show oxygen evolution activity and good solar light transmission

Molecular layer deposition (MLD) of hybrid organic-inorganic thin films called "vanadicones" was investigated using tetrakisethylmethylaminovanadium (TEMAV) as the metal precursor and glycerol (GL) or ethylene glycol (EG) as the organic reactant. Linear and continued growth could only be achieved with GL as the organic reactant. The TEMAV/GL process displayed self-limiting reactions for both precursor and reactant pulses in the temperature range from 80 °C to 180 °C, with growth rates of 1.2 to 0.5 Å per cycle, respectively. Infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) revealed the hybrid nature of the films. From X-ray reflectivity, the density was estimated at 2.6 g cm. A series of 21 nm vanadicone films were subjected to annealing under oxidizing (air) or inert (He) atmospheres at 500 °C. During annealing in air, the film crystallized to the VO phase and all carbon was removed from the film. The films annealed in helium remained amorphous and retained most of their carbon content. Electrochemical measurements revealed lithium-ion activity during cyclic voltammetry in all treated films, while the as deposited film was inactive. In the 2.9 to 3.5 V vs. Li/Li potential region, no improvement over the VO reference was observed. However, the helium annealed samples outperformed VO in terms of capacity, rate performance and cyclability when charged and discharged in the 1.0 to 3.5 V vs. Li/Li region. This result enables the application of VO-based hybrid electrodes in a wider potential range without sacrificing the stability and performance.

Atomic layer deposition (ALD) of a wide range of Mn oxides (MnO to MnO 2 ) is demonstrated by combining the Mn(thd) 3 (tris(2,2,6,6-tetramethyl-3,5-heptanedionato)manganese) precursor with different types of plasma activated reactant gases. Typical ALD behavior is found with hydrogen, ammonia, and water plasma, with a fully precursor controlled temperature window (from 140 to 250 °C) and constant growth rate (0.022 ± 0.001 nm/cycle). A purely ligandexchange chemistry would predict Mn 2 O 3 films with the transition metal in the +III state. However, it is found that the nature of the processgas or -plasma, more specific its oxidizing/reducing character, largely determines the oxidation state of the grown films. Our approach provides an effective method for the deposition of MnO 2 (+IV), Mn 3 O 4 (+II/+III), and MnO(+II) based on the Mn(thd) 3 (+III) precursor. All as-deposited films are found to be smooth (<1.2 nm rms roughness), crystalline and with <6% impurities. The resulting films are tested as lithium-ion battery electrodes, showing the MnO 2 and the MnO films as possible candidate thin-film cathode and anode, respectively.

Flexible wearable electronics and on-chip energy storage for wireless sensors drive rechargeable batteries toward thin-film lithium ion batteries. To enable more charge storage on a given surface, higher energy density materials are required, while faster energy storage and release can be obtained by going to thinner films. Vanadium oxides have been examined as cathodes in classical and thin-film lithium ion batteries for decades, but amorphous vanadium oxide thin films have been mostly discarded. Here, we investigate the use of atomic layer deposition, which enables electrode deposition on complex three-dimensional (3D) battery architectures, to obtain both amorphous and crystalline VO2 and V2O5, and we evaluate their thin-film cathode performance. Very high volumetric capacities are found, alongside excellent kinetics and good cycling stability. Better kinetics and higher volumetric capacities were observed for the amorphous vanadium oxides compared to their crystalline counterparts. The conformal deposition of these vanadium oxides on silicon micropillar structures is demonstrated. This study shows the promising potential of these atomic layer deposited vanadium oxides as cathodes for 3D all-solid-state thin-film lithium ion batteries.