Polyelectrolyte multilayer-like films from layer-by-layer processing of protected polyampholytic block copolymers.

Polyelectrolyte multilayer films (PEMs) are conventionally prepared by a layer-by-layer (LbL) deposition of alternating polycation and polyanion solutions. We introduce herein a block copolymer (BCP) approach employing a BCP with an H-bond acceptor block and a protected H-donor block as a masked polyampholyte to form new types of PEMs.

Double-heterojunction nanorod light-responsive LEDs for display applications.

Dual-functioning displays, which can simultaneously transmit and receive information and energy through visible light, would enable enhanced user interfaces and device-to-device interactivity. We demonstrate that double heterojunctions designed into colloidal semiconductor nanorods allow both efficient photocurrent generation through a photovoltaic response and electroluminescence within a single device. These dual-functioning, all-solution-processed double-heterojunction nanorod light-responsive light-emitting diodes open feasible routes to a variety of advanced applications, from touchless interactive screens to energy harvesting and scavenging displays and massively parallel display-to-display data communication.

Multilayer Transfer Printing for Pixelated, Multicolor Quantum Dot Light-Emitting Diodes.

Here, we report multilayer stacking of films of quantum dots (QDs) for the purpose of tailoring the energy band alignment between charge transport layers and light emitting layers of different color in quantum dot light-emitting diodes (QD LED) for maximum efficiency in full color operation. The performance of QD LEDs formed by transfer printing compares favorably to that of conventional devices fabricated by spin-casting. Results indicate that zinc oxide (ZnO) and titanium dioxide (TiO2) can serve effectively as electron transport layers (ETLs) for red and green/blue QD LEDs, respectively.

Orientation Control in Thin Films of a High-χ Block Copolymer with a Surface Active Embedded Neutral Layer.

Directed self-assembly (DSA) of block copolymers (BCPs) is an attractive advanced patterning technology being considered for future integrated circuit manufacturing. By controlling interfacial interactions, self-assembled microdomains in thin films of polystyrene-block-poly(methyl methacrylate), PS-b-PMMA, can be oriented perpendicular to surfaces to form line/space or hole patterns. However, its relatively weak Flory interaction parameter, χ, limits its capability to pattern sub-10 nm features.

DNA-mediated control of metal nanoparticle shape: one-pot synthesis and cellular uptake of highly stable and functional gold nanoflowers.

The effects of different DNA molecules of the same length on the morphology of gold nanoparticles during synthesis are investigated. While spherical nanoparticles (AuNS) are observed in the presence of 30-mer poly T, like that in the absence of DNA, 30-mer poly A or poly C induces formation of the flower-shaped gold nanoparticle (AuNF). Detailed mechanistic studies indicate that the difference in DNA affinity to the AuNP plays a major role in the different morphology control processes.