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Nanostructured block copolymer (BCP) thin films enable the formation on‐demand of a variety of periodic patterns at the nanometer scale by tuning the macromolecular BCP characteristics and annealing processes. Significant progress in the control of the self‐assembly has been witnessed over the past decade with the implementation of robust directed self‐assembly methods. However, the self‐assembled structural patterns obtained at equilibrium are limited and methods to expand the range of structural configurations are required to harness additional functionalities. Here, this work demonstrates how polystyrene‐b‐poly(methyl methacrylate) BCP thin layers can be stacked to produce a library of complex 3D hierarchical heterostructures. In this iterative assembly process based on simple building bricks (i.e., immobilized BCP patterns forming Holes, Lines and Dots), the stacking configuration (i.e., self‐assembly and registration) of a BCP thin film is directed with respect to the previous layer using confinement effects and interfacial energy tuning. This responsive layering can lead to intricate 3D Al2O3 structures and opens the way to a broad variety of structural designs toward functional applications. [ABSTRACT FROM AUTHOR]

In this work, we investigated the self-assembly of a lamellar block copolymer (BCP) under different wetting conditions. We explored the influence of the chemical composition of under-layers and top-coats on the thin film stability, self-assembly kinetics and BCP domain orientation. Three different chemistries were chosen for these surface affinity modifiers and their composition was tuned in order to provide either neutral wetting (i.e. an out-of-plane lamellar structure), or affine wetting conditions (i.e. an in-plane lamellar structure) with respect to a sub-10 nm PS- b -PDMSB lamellar system. Using such controlled wetting configurations, the competition between the dewetting of the BCP layer and the self-organization kinetics was explored. We also evaluated the spreading parameter of the BCP films with respect to the configurations of surface-energy modifiers and demonstrated that BCP layers are intrinsically unstable to dewetting in a neutral configuration. Finally, the dewetting mechanisms were evaluated with respect to the different wetting configurations and we clearly observed that the rigidity of the top-coat is a key factor to delay BCP film instability. [ABSTRACT FROM AUTHOR]

The black perovskite phase of CsPbI3 is promising for optoelectronic applications; however, it is unstable under ambient conditions, transforming within minutes into an optically inactive yellow phase, a fact that has so far prevented its widespread adoption. Here we use coarse photolithography to embed a PbI2-based interfacial microstructure into otherwise-unstable CsPbI3 perovskite thin films and devices. Films fitted with a tessellating microgrid are rendered resistant to moisture-triggered decay and exhibit enhanced long-term stability of the black phase (beyond 2.5 years in a dry environment), due to increasing the phase transition energy barrier and limiting the spread of potential yellow phase formation to structurally isolated domains of the grid. This stabilizing effect is readily achieved at the device level, where unencapsulated CsPbI3 perovskite photodetectors display ambient-stable operation. These findings provide insights into the nature of phase destabilization in emerging CsPbI3 perovskite devices and demonstrate an effective stabilization procedure which is entirely orthogonal to existing approaches. Lattice anchoring, in its varied forms, has proven effective at regulating the energetics of metastable phases of polymorphic crystals. Here, the authors utilize top-down photolithography to embed a tessellating 3D interfacial network into otherwise-unstable CsPbI3 perovskite thin films and devices, stabilizing the perovskite phase. [ABSTRACT FROM AUTHOR]

Nanostructured block copolymer (BCP) thin films constitute an elegant tool to generate complex periodic patterns with periodicities ranging from a few nanometers to hundreds of nanometers. Such well‐organized nanostructures are foreseen to enable next‐generation nanofabrication research with potent applications in the design of functional materials in biology, optics or microelectronics. This valuable platform is, however, limited by the geometric features attainable from diblock copolymer architectures considering the thermodynamic driving force leaning toward the formation of structures minimizing the interface between the blocks. Therefore, strategies to enrich the variety of structures obtained by BCP self‐assembly processes are gaining momentum and this progress report reviews the opportunities inherent to iterative BCP self‐assembly by considering the emerging strategies for the generation of "non‐native" morphologies. [ABSTRACT FROM AUTHOR]

The authors report here on the optical response and extraction of the morphological properties of three sizes of self-assembled nearly hexagonal arrays of gold (Au) nanoparticles (NPs), deposited on the native oxide on c-Si. The arrays were prepared by templating gold NP growth with self-assembled cylindrically organized block copolymer thin films, with consecutive removal of the polymer matrix by plasma etching. The particle sizes were controlled by using block copolymers of different molecular weights when assembling the templates. The resulting gold nanostructures were characterized by scanning probe microscopy. Spectroscopic ellipsometry was used to record the optical response of the samples, and the modeling of the spectra and the extraction of morphological parameters were performed using a modification of the Bedeaux–Vlieger formalism implemented in GranFilm. The modeling issues upon the introduction of a thin intermediate (oxide) layer between the particle and the substrate are discussed in detail, and a solution to the model procedure is proposed. The particles were modeled as truncated oblate Au spheroids in a hexagonal lattice on the native oxide on c-Si. The model fit converged to a solution indicating that the particles present a low wetting of the native oxide substrate, with parameters describing the particles and lattice in good correspondence with AFM. The extended GranFilm model simulations are also supported by finite element modeling. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and self‐assembly in thin‐film configuration of linear ABC triblock terpolymer chains consisting of polystyrene (PS), poly(2‐vinylpyridine) (P2VP), and polyisoprene (PI) are described. For that purpose, a hydroxyl‐terminated PS‐b‐P2VP (45 kg mol−1) building block and a carboxyl‐terminated PI (9 kg mol−1) are first separately prepared by anionic polymerization, and then are coupled via a Steglich esterification reaction. This quantitative and metal‐free catalyst synthesis route reveals to be very interesting since functionalization and purification steps are straightforward, and well‐defined terpolymers are produced. A solvent vapor annealing (SVA) process is used to promote the self‐assembly of frustrated PS‐b‐P2VP‐b‐PI chains into a thin‐film core–shell double gyroid (Q230, space group: Ia 3 ¯d) structure. As terraces are formed within PS‐b‐P2VP‐b‐PI thin films during the SVA process under a CHCl3 vapor, different plane orientations of the Q230 structure ((211), (110), (111), and (100)) are observed at the polymer–air interface depending on the film thickness. [ABSTRACT FROM AUTHOR]

Abstract: Nanotemplates derived from the self‐assembly of AB‐type block copolymers provide an elegant route to achieve well‐defined metallic dot arrays, even if the variety of pattern symmetries is restricted due to the limited number of structures offered by microphase separated diblock copolymers. A strategy that relies on the use of complex network structures accessible through the self‐assembly of linear ABC‐type terpolymers is presented for the formation of metallic nanodots arrays with “outside‐the‐box” symmetries. Patterned templates formed by the cubic Q214 and orthorhombic O70 network structures are used as excellent platforms to build well‐ordered gold nanodot arrays with unique p3m1 and p2 symmetries, respectively. A simple yet efficient blending strategy is used to tune the critical dimensions of the p3m1 pattern while laterally ordered gold nanodot arrays are also demonstrated through a directed self‐assembly approach. Such highly ordered gold nanodots with tunable particle dimensions and array periods, enabling the control of their plasmonic responses, are attractive probes for biological imaging. [ABSTRACT FROM AUTHOR]

• Introduction covers criteria of nanomanufacturing and concepts of block copolymers in thin film and solution state. • Next, state-of-the-art in block copolymer thin film and solution processing is described. • Overview of key contribution of block copolymers in energy, environmental, photonic, and biological applications. • Outlook for impact and influence of block copolymers in nanomanufacturing including areas such as catalysis, membranes, metasurfaces and drug delivery nanodevices. Self-assembly approaches, e.g. colloidal, emulsion and polymer phase separation, provide scientists with an exotic yet direct platform to access technologically desired nanostructures at competitive costs. In particular, soft nanomaterial systems such as block copolymer (BCP) materials present a powerful means to tailor templates and spatially controlled systems that are amenable to large scale manufacturing practices. BCP nanoarchitectures in bulk, solution and thin film form can act as structural motifs to template foreign materials and pave the way towards important applications across industry and society. While extensive literature and research efforts exist on electronic device uses using BCPs, we look at nascent applications outside the integrated circuit realm. Recent reports are discussed including for example; light-harvesting (energy – section 2), metasurfaces (photonics – section 3), nanofiltration membranes (environmental – section 4) and antibacterial activity (biological – section 5). We endeavour to illustrate the window of opportunity presented through BCP self-assembly for nanomanufacturing. We believe the highlights discussed will aid in directing new research initiatives and facilitate the large-scale integration of BCP materials with broad societal impact. [ABSTRACT FROM AUTHOR]

3‐Miktoarm star terpolymer architecture (3µ‐ABC), consisting of three dissimilar polymer chains, A, B, and C connected at a junction point, provides a unique opportunity in the design of complex nanoscale patterns such as Archimedean tilings that are not accessible from linear ABC terpolymers. In this work, the synthesis and the self‐assembly of 3‐miktoarm star terpolymers, namely, polystyrene‐arm‐poly(2‐vinylpyridine)‐arm‐polyisoprene (3µ‐SPI) into Archimedean tiling patterns is described. Several 3µ‐SPI terpolymers are produced via a mid‐functional PS‐b‐P2VP, synthesized by sequential anionic polymerization, using a 1,1‐diphenylethylene bearing a tert‐butyldimethylsilyl–protected hydroxyl functionality as a core molecule. PI arms with different sizes are then linked to the deprotected hydroxyl function of the core molecule via a Steglich esterification. Solvent‐annealed 3µ‐SPI thin films exhibit nanoscale prisms arranged into a (4.6.12) Archimedean tiling pattern. Depending on the size of the low etch‐resistant PI arm and the solvent selected to promote the self‐assembly of 3µ‐SPI thin films, the voided columns occupy the square or decagonal sites of the (4.6.12) pattern. The use of this (4.6.12) tiling produced for the first time from self‐assembled 3µ‐ABC thin films can be a promising route to build 2D photonic crystals having complete photonic band gaps, where the light propagation is completely prohibited. Several (4.6.12) Archimedean tiling patterns derived from the self‐assembly of 3‐miktoarm star terpolymer thin films are demonstrated for the first time. The use of this (4.6.12) tiling can be a promising route to build 2D photonic crystals having complete photonic band gaps, where the light propagation is completely prohibited. [ABSTRACT FROM AUTHOR]

Spin coating is one of the most versatile methods to generate nanostructured block copolymer (BCP) thin films which are highly desired for many applications such as nanolithography or organic electronics. The self‐assembly pathways through phase separation, both in solvent and in bulk, strongly influence the final BCP structure obtained after spin coating. As a demonstration, the formation of highly ordered in‐plane lamellae is elucidated herein by using in situ grazing incidence small‐angle X‐ray scattering. A key step in this complex fast organization process is the formation of intermediate micellar phases triggered by solvent affinity toward one of the block. Indeed, directional coalescence of a short‐lived intermediate hexagonal structure of cylindrical micelles enables the development of a final highly ordered lamellar structure, predominantly oriented parallel to the substrate surface. These results suggest that the existence of such transient micellar phases is a crucial process in order to produce highly ordered structures with a specific orientation directly after the BCP thin film deposition; and should be the focus of further optimization for the directed self‐assembly and, more generally, in the bottom‐up nanostructure fabrication. In situ GISAXS experiments reveal the subsecond self‐assembly dynamics of block copolymer (BCP) structuring during spin coating. Two distinct transient micellar structures triggered by the solvent selectivity are responsible for the formation of a fully oriented lamellar phase directly after casting. Visualizing the transient states occurring during spin coating opens new avenues to finely tune the nanostructured BCP thin films. [ABSTRACT FROM AUTHOR]

Room temperature flexible heat harvesters based on conducting polymers are ideally suited to cover the energy demands of the modern nomadic society. The optimization of their thermoelectric efficiency is usually sought by tuning the oxidation levels of the conducting polymers, even if such methodology is detrimental to the Seebeck coefficient ( S ) as both the Seebeck coefficient and the electrical conductivity ( σ ) are antagonistically related to the carrier concentration. Here we report a concurrent increase of S and σ and we experimentally derive the dependence of Seebeck coefficient on charge carrier mobility for the first time in organic electronics. Through specific control of the conducting polymer synthesis, we enabled the formation of a denser percolation network that facilitated the charge transport and the thermodiffusion of the charge carriers inside the conducting polymer layer, while the material shifted from a Fermi glass towards a semi-metal, as its crystallinity increased. This work sheds light upon the origin of the thermoelectric properties of conducting polymers, but also underlines the importance of enhanced charge carrier mobility for the design of efficient thermoelectric polymers. [ABSTRACT FROM AUTHOR]

Among functional materials, π-conjugated polymers are very attractive for large-scale or wearable applications thanks to their electronic and soft-matter properties. Poly (3,4-ethylenedioxythiophene) (PEDOT) based materials are often considered as the flagships of polymer electronics. Indeed, their tunable doping level affords various electronic transport behaviors, i.e. metallic, semi-metallic, or semi-conductor, with respect to the targeted applications. Furthermore, reducing the size of functional objects is a cornerstone of the semi-conductor industry's drive for improved performance. Hence, the nanopatterning of π-conjugated polymers and its relationship to electronic behavior is of high interest for future developments in polymer electronics. Here we report the texturation of PEDOT:Tos thin films at the nanometer scale via block copolymer lithography using self-assembled poly(styrene)- block -poly(methyl methacrylate) (PS- b -PMMA) layers as masks. By means of imaging and electronic spectral analyses, we demonstrate that doped-PEDOT nanostructures can be obtained by this process through a re-doping treatment, enabling the recovery of the majority of the electronic states of the nanotextured PEDOT:Tos layer. [Display omitted] • Lithographic masks derived from BCP self-assembly were used. • Hexagonal array of nano-sized PEDOT:Tos dots has been achieved. • AcIdic treatment yields the recovery of the majority of the electronic states of the nanotextured PEDOT:Tos layer. [ABSTRACT FROM AUTHOR]