Key Factor Study for Amphiphilic Block Copolymer‐Templated Mesoporous SnO₂ Thin Film Synthesis: Influence of Solvent and Catalyst

Abstract

Nanostructured SnO 2 thin films were widely investigated during the past decades because of its wide band gap. Accordingly, they are used in various applications such as lithium-ion batteries, [1-11] solar cells, [12-20] solar water splitting, [21] gas sensing [20,22-32] and photoluminescence. [33] Methods reported in the literature for preparing nanostructured SnO 2 thin films include solvothermal synthesis, [3,34,35] reverse microemulsion synthesis, [36] sol-gel synthesis, [37-43] sputter deposition, [28,44] chemical vapor deposition, [29,33,45] electro spinning, [46] and electro deposition. [47] Among these preparation approaches, in particular the block copolymer-assisted sol-gel chemistry approach features advantages in terms of enabling a large-scale production, since most of the sol-gel reaction can be performed without complicated equipment in ambient conditions. Moreover, it is possible to assemble inorganic clusters into thin films with well-controlled crystal sizes, composition, and homogeneity. [48] For example, Brezesinski and co-authors synthesized crack-free, mesoporous SnO 2 films by using the amphiphilic diblock copolymer poly(ethylene-co-butylene)block-poly(ethylene oxide) and the crystallization mechanisms as well as the mesostructural evolution were investigated by a specially constructed 2D small-angle X-ray scattering setup. [49] Roose and co-authors fabricated mesoporous SnO 2 electron selective contacts of perovskite solar cells based on the block copolymer poly(1,4-isoprene-b-ethylene oxide) to achieve stable perovskite solar cells, which showed good performance under UV light in an inert atmosphere. [15] Chi and co-authors synthesized a series of mesoporous SnO 2 thin films with the amphiphilic graft copolymer poly(vinyl chloride)-g-poly(oxyethylene methacrylate), which showed significantly different gassensing performances as a function of the SnO 2 porosity. [30] Although mesoporous SnO 2 thin films prepared with block copolymer templates have shown applications in many fields, the key factors governing the final film morphology during the preparation process were rarely discussed. However, a more detailed understanding of the reaction conditions for the block copolymer-assisted sol-gel chemistry approach to synthesize As a crucial material in the field of energy storage, SnO 2 thin films are widely applied in daily life and have been in the focus of scientific research. Compared to the planar counterpart, mesoporous SnO 2 thin films with high specific surface area possess more attractive physical and chemical properties. In the present work, a novel amphiphilic block copolymer-assisted sol-gel chemistry is utilized for the synthesis of porous tin oxide (SnO 2). Two key factors for the sol-gel stock solution preparation, the solvent category and the catalyst content, are systematically varied to tune the thin film morphologies. A calcination process is performed to remove the polymer template at 500 °C in ambient conditions. The surface morphology and the buried inner structure are pro...

Multidimensional Morphology Control for PS‐b‐P4VP Templated Mesoporous Iron (III) Oxide Thin Films

“…In addition, the corresponding radii of the second structure are fitted to be (5.6 ± 0.3), (4.5 ± 0.4), and (5.0 ± 0.4) nm. Based on the fitted center‐to‐center distances and radii, the pore sizes formed by the nanostructures can be calculated with the approach [ 34,52 ] …”

“…Related research in our group demonstrated the prominent influence of the PS-b-P 4 VP concentration on the ZnO morphology and the solvent effect during the polystyrene-block-polyethylene oxide (PS-b-PEO) templated TiO 2 and SnO 2 synthesis. [26,34,35] The formation of thermodynamically stable block polymer micelles is mainly governed by the following three contributions: The stretching degree of the core-forming polymer chains, the interfacial tension between the micelle core and the surrounding solvent, and the repulsive interactions among corona-forming chains. [25] The first two contributions can be affected by factors including copolymer composition and concentration, poor solvent content in the solution, and the preferential affinity of the common solvent.…”

“…Related research in our group demonstrated the prominent influence of the PS‐b‐P 4 VP concentration on the ZnO morphology and the solvent effect during the polystyrene‐block‐polyethylene oxide (PS‐b‐PEO) templated TiO 2 and SnO 2 synthesis. [ 26,34,35 ]…”

Recent progress in block copolymer soft-template-assisted synthesis of versatile mesoporous materials for energy storage systems

“…To provide a stable supply that meets the massive energy requirement of modern society, effective energy storage systems (ESSs) should be developed. [1][2][3][4][5][6][7][8][9][10][11][12][13] Energy storage devices broadly consist of electrolytes, active materials, and current collectors. 14,15 In general, energy storage is achieved through the redox reaction between the electrolyte and active materials.…”

In Situ GISAXS Observation and Large Area Homogeneity Study of Slot-Die Printed PS-b-P4VP and PS-b-P4VP/FeCl3 Thin Films

“…Nanostructured hematite (α-Fe 2 O 3 ) thin films are highly promising for applications as photoelectrodes or electrochemical electrodes in energy conversion and storage including photovoltaic devices, , lithium-ion batteries, − sensors, − and photocatalysis − because of their nontoxicity, high abundance, and superior electrochemical stability. Several routes for synthesizing nanostructured α-Fe 2 O 3 thin films were reported such as the hydrothermal method, laser ablation, and the sol–gel method. ,− Among these available physical or chemical synthesis approaches, solution-processable sol–gel methods are particularly attractive because of their potential advantages such as simplicity, low-cost fabrication, and compatibility with large-scale thin film deposition techniques. ,− Moreover, the self-assembly of amphiphilic block copolymers was widely used for the synthesis of thin films with periodically ordered nanostructures, such as spheres, cylinders, and lamellae. − By means of block copolymer assisted sol–gel chemistry, various mesoporous metal oxide thin films were prepared and the specific nanostructure was fine-adjusted by the components in the stock solution, the preferential affinity of the solvent to the polymer chains, and duration of the sol–gel reaction. − To date, most amphiphilic block copolymer templated α-Fe 2 O 3 thin film syntheses are still performed based on a lab-scale spin-coating process, which is not suitable for a cost-effective fabrication of photoelectrodes or electrochemical electrodes in energy conversion and storage. Spray coating and printing are two well-established industrial-scale thin film deposition techniques.…”