Block Copolymer with an Extremely High Block-to-Block Interaction for a Significant Reduction of Line-Edge Fluctuations in Self-Assembled Patterns

Directed self-assembly (DSA) of block copolymers (BCPs) with a high Flory–Huggins interaction parameter (χ) provides advantages of pattern size reduction below 10 nm and improved pattern quality. Despite theoretical predictions, however, the questions of whether BCPs with a much higher χ than conventional high-χ BCPs can further improve the line edge roughness (LER) and how to overcome their extremely slow self-assembly kinetics remain unanswered. Here, we report the synthesis and assembly of poly­(4vinylpyridine-<i>b</i>-dimethylsiloxane) BCP with an extremely high χ-parameter (estimated to be approximately 7 times higher compared to that of poly­(styrene-<i>b</i>-dimethylsiloxane) – a conventional high-χ BCP) and achieve a markedly low 3σ line edge roughness of 0.98 nm, corresponding to 6% of its line width. Moreover, we demonstrate the successful application of an ethanol-based 60 °C warm solvent annealing treatment to address the extremely slow assembly kinetics of the extremely high-χ BCP, considerably reducing the self-assembly time from several hours to a few minutes. This study suggests that the use of BCPs with an even larger χ could be beneficial for further improvement of self-assembled BCP pattern quality

Spontaneous Registration of Sub-10 nm Features Based on Subzero Celsius Spin-Casting of Self-Assembling Building Blocks Directed by Chemically Encoded Surfaces

For low-cost and facile fabrication of innovative nanoscale devices with outstanding functionality and performance, it is critical to develop more practical patterning solutions that are applicable to a wide range of materials and feature sizes while minimizing detrimental effects by processing conditions. In this study, we report that area-selective sub-10 nm pattern formation can be realized by temperature-controlled spin-casting of block copolymers (BCPs) combined with submicron-scale-patterned chemical surfaces. Compared to conventional room-temperature spin-casting, the low temperature (<i>e.g.</i>, −5 °C) casting of the BCP solution on the patterned self-assembled monolayer achieved substantially improved area selectivity and uniformity, which can be explained by optimized solvent evaporation kinetics during the last stage of film formation. Moreover, the application of cold spin-casting can also provide high-yield <i>in situ</i> patterning of light-emitting CdSe/ZnS quantum dot thin films, indicating that this temperature-optimized spin-casting strategy would be highly effective for tailored patterning of diverse organic and hybrid materials in solution phase

Area-Selective Lift-Off Mechanism Based on Dual-Triggered Interfacial Adhesion Switching: Highly Facile Fabrication of Flexible Nanomesh Electrode

With the recent emergence of flexible and wearable optoelectronic devices, the achievement of sufficient bendability and stretchability of transparent and conducting electrodes (TCEs) has become an important requirement. Although metal-mesh-based structures have been investigated for TCEs because of their excellent performances, the fabrication of mesh or grid structures with a submicron line width is still complex due to the requirements of laborious lithography and pattern transfer steps. Here, we introduce an extremely facile fabrication technique for metal patterns embedded in a flexible substrate based on submicron replication and an area-selective delamination (ASD) pattern. The high-yield, area-specific lift-off process is based on the principle of solvent-assisted delamination of deposited metal thin films and a mechanical triggering effect by soft wiping or ultrasonication. Our fabrication process is very simple, convenient, and cost-effective in that it does not require any lithography/etching steps or sophisticated facilities. Moreover, their outstanding optical and electrical properties (<i>e.g.</i>, sheet resistances of 0.43 Ω sq^–1 at 94% transmittance), which are markedly superior to those of other flexible TCEs, are demonstrated. Furthermore, there is no significant change of resistance over 1000 repeated bending cycles, with a bending radius of 5 mm, and immersion in various solvents such as salt water and organic solvents. Finally, we demonstrate high-performance transparent heaters and flexible touch panels fabricated using the nanomesh electrode, confirming the long-range electrical conduction and reliability of the electrode

Area-Selective Lift-Off Mechanism Based on Dual-Triggered Interfacial Adhesion Switching: Highly Facile Fabrication of Flexible Nanomesh Electrode

With the recent emergence of flexible and wearable optoelectronic devices, the achievement of sufficient bendability and stretchability of transparent and conducting electrodes (TCEs) has become an important requirement. Although metal-mesh-based structures have been investigated for TCEs because of their excellent performances, the fabrication of mesh or grid structures with a submicron line width is still complex due to the requirements of laborious lithography and pattern transfer steps. Here, we introduce an extremely facile fabrication technique for metal patterns embedded in a flexible substrate based on submicron replication and an area-selective delamination (ASD) pattern. The high-yield, area-specific lift-off process is based on the principle of solvent-assisted delamination of deposited metal thin films and a mechanical triggering effect by soft wiping or ultrasonication. Our fabrication process is very simple, convenient, and cost-effective in that it does not require any lithography/etching steps or sophisticated facilities. Moreover, their outstanding optical and electrical properties (<i>e.g.</i>, sheet resistances of 0.43 Ω sq^–1 at 94% transmittance), which are markedly superior to those of other flexible TCEs, are demonstrated. Furthermore, there is no significant change of resistance over 1000 repeated bending cycles, with a bending radius of 5 mm, and immersion in various solvents such as salt water and organic solvents. Finally, we demonstrate high-performance transparent heaters and flexible touch panels fabricated using the nanomesh electrode, confirming the long-range electrical conduction and reliability of the electrode