Mesoporous nanoparticle layers of transparent conductive oxides (TCO) with anchored organic dyes are of great interest for electrochromic applications. Herein, we prepared mesoporous layers of antimony doped tin oxide (ATO)...

Integration of solvothermal reaction products into complex thin-layer architectures is frequently achieved by combinations of layer transfer and subtractive lithography, whereas direct additive substrate patterning with solvothermal reaction products has remained challenging. We report reactive additive capillary stamping under solvothermal conditions as a parallel contact-lithographic access to patterns of solvothermal reaction products in thin-layer configurations. To this end, corresponding precursor inks are infiltrated into mechanically robust mesoporous aerogel stamps derived from double-network hydrogels. The stamp is then brought into contact with a substrate to be patterned under solvothermal reaction conditions inside an autoclave. The precursor ink forms liquid bridges between the topographic surface pattern of the stamp and the substrate. Evaporation-driven enrichment of the precursors in these liquid bridges, along with their liquid-bridge-guided conversion into the solvothermal reaction products, yields large-area submicron patterns of the solvothermal reaction products replicating the stamp topography. For example, we prepared thin hybrid films, which contained ordered monolayers of superparamagnetic submicron nickel ferrite dots prepared by solvothermal capillary stamping surrounded by nickel electrodeposited in a second orthogonal substrate functionalization step. The submicron nickel ferrite dots acted as a magnetic hardener, halving the remanence of the ferromagnetic nickel layer. In this way, thin-layer electromechanical systems, transformers, and positioning systems may be customized.

Thin micropatterned lithium niobate (LiNbO3) layers may be used for photonic components, actuators, and data storage devices because LiNbO3 exhibits nonlinear optical properties as well as anisotropic polarizability and ferroelectric behavior. Commonly, thin micropatterned LiNbO3 layers are integrated into device architectures by complex manufacturing algorithms including direct wafer bonding, mechanochemical wafer thinning or mechanical cleavage of thin LiNbO3 layers from bulk LiNbO3 crystals, as well as lithographic pattering of and/or pattern transfer into the thin LiNbO3 layers. The high‐throughput generation of thin microstructured LiNbO3 layers by parallel additive capillary stamping of environmentally friendly aqueous LiNbO3 precursor solutions with topographically patterned porous polymer stamps is reported. The precursor solutions contain the cheap, commercially available compounds lithium acetate and niobium oxalate hydrate, which are simply dissolved in water as received. In this way, rough surfaces not suitable for layer transfer methods involving direct wafer bonding, such as the surfaces of indium tin oxide (ITO) substrates, are functionalized with microstructured LiNbO3 layers. Microstructured holey 100 nm‐thick LiNbO3 films showing uniform second‐harmonic generation (SHG) except at the positions of the holes are obtained. Orthogonal substrate formation is demonstrated by electrodeposition of gold into the holes, which increases the SHG output 5.4 times.

Charge storage layers are an important component of electrochromic devices, which are expected to exhibit high storage capacity and transparency as well as fast electron transfer rates. However, these layers often rely on the (de)intercalation of ions into the crystal lattice of the material and therefore require optimization to be compatible with non‐intercalating electrolytes. In this report, the post‐modification of mesoporous antimony‐doped tin oxide (ATO) nanoparticle layers with a redox‐active cerium compound is described. In particular, the switching of the Ce3+/Ce4+ couple on the conductive nanoparticle scaffold is demonstrated using tetrabutylammonium perchlorate as a non‐intercalating electrolyte. Remarkably, high storage capacities of up to 27 mC cm−2 and transmittance values of ≈90% are achieved. Variation of the antimony doping concentration revealed that nanoparticle layers doped with 15% Sb exhibit the highest capacity, which can be attributed to increased conductivity in the potential range where the Ce3+ ions are oxidized. Finally, the cerium‐modified ATO films show promising performance as charge storage layers in an electrochromic device with a viologen‐anchored ATO layer as the electrochromic working electrode. Switching times of ≈0.4 s highlight the fast electron transfer capability of the cerium‐decorated ATO layer, even when a non‐intercalating electrolyte is used.

High‐temperature treatment of functional nanomaterials, through postsynthesis calcination, often represents an important step to unlock their full potential. However, such calcination steps usually severely limit the preparation of colloidal solutions of the nanoparticles due to the formation of sintered agglomerates. Herein, a simple route is reported to obtain colloidal solutions of calcined n‐conductive antimony doped tin oxide (ATO) as well as titanium dioxide (TiO2) nanoparticles without the need for additional sacrificial materials. This is achieved by making use of the reduced contact between individual nanoparticles when they are assembled into aerogels. Following the calcination of the aerogels at 500 °C, redispersion of the nanoparticles into stable colloidal solutions with various solvents can be achieved. Although a slight degree of sintering is inevitable, the size of the resulting aggregates in solution is still remarkably small with values below 30 nm.