Increased Brightness and Reduced Efficiency Droop in Perovskite Quantum Dot Light-Emitting Diodes Using Carbazole-Based Phosphonic Acid Interface Modifiers.

We demonstrate the use of [2-(9-carbazol-9-yl)ethyl]phosphonic acid (2PACz) and [2-(3,6-di--butyl-9-carbazol-9-yl)ethyl]phosphonic acid (-Bu-2PACz) as anode modification layers in metal-halide perovskite quantum dot light-emitting diodes (QLEDs). Compared to conventional QLED structures with PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrenesulfonate)/PVK (poly(9-vinylcarbazole)) hole-transport layers, the QLEDs made with phosphonic acid (PA)-modified indium tin oxide (ITO) anodes show an over seven-fold increase in brightness, achieving a brightness of 373,000 cd m, one of the highest brightnesses reported to date for colloidal perovskite QLEDs. Importantly, the onset of efficiency roll-off, or efficiency droop, occurs at ∼1000-fold higher current density for QLEDs made with PA-modified anodes compared to control QLEDs made with conventional PEDOT:PSS/PVK hole transport layers, allowing the devices to sustain significantly higher levels of external quantum efficiency at a brightness of >10 cd m.

Polythiophene side chain chemistry and its impact on advanced composite anodes for lithium-ion batteries.

In the development of high-performance lithium-ion batteries (LIBs), the design of polymer binders, particularly through manipulation of side-chain chemistry, plays a pivotal role in optimizing electrode stability, ion transport, and adaptability to the volume changes during cycling. In particular, poly[3-(potassium-4-butanoate)thiophene-2,5-diyl] (P3KBT) increases magnetite and silicon capacity and cycling stability. This work explores the impact of polythiophene alkyl sidechain length on anode characteristics, aiming to enhance performance in LIBs.

Controlling Ion Uptake in Carboxylated Mixed Conductors.

Organic mixed ionic-electronic conductors (OMIECs) have garnered significant attention due to their capacity to transport both ions and electrons, making them ideal for applications in energy storage, neuromorphics, and bioelectronics. However, charge compensation mechanisms during the polymer redox process remain poorly understood, and are often oversimplified as single-ion injection with little attention to counterion effects. To advance understanding and design strategies toward next-generation OMIEC systems, a series of p-channel carboxylated mixed conductors is investigated.

Stress-Relieving Carboxylated Polythiophene/Single-Walled Carbon Nanotube Conductive Layer for Stable Silicon Microparticle Anodes in Lithium-Ion Batteries.

Stress-relieving and electrically conductive single-walled carbon nanotubes (SWNTs) and conjugated polymer, poly[3-(potassium-4-butanoate)thiophene] (PPBT), wrapped silicon microparticles (Si MPs) have been developed as a composite active material to overcome technical challenges such as intrinsically low electrical conductivity, low initial Coulombic efficiency, and stress-induced fracture due to severe volume changes of Si-based anodes for lithium-ion batteries (LIBs). The PPBT/SWNT protective layer surrounding the surface of the microparticles physically limits volume changes and inhibits continuous solid electrolyte interphase (SEI) layer formation that leads to severe pulverization and capacity loss during cycling, thereby maintaining electrode integrity. PPBT/SWNT-coated Si MP anodes exhibited high initial Coulombic efficiency (85%) and stable capacity retention (0.

Harnessing Compositional Gradients to Elucidate Phase Behaviors toward High Performance Polymer Semiconductor Blends.

Polymer semiconductor/insulator blends offer a promising avenue to achieve desired mechanical properties, environmental stability, and high device performance in organic field-effect transistors. A comprehensive understanding of process-structure-property relationships necessitates a thorough exploration of the composition space to identify transitions in performance, morphology, and phase behavior. Hence, this study employs a high-throughput gradient thin film library, enabling rapid and continuous screening of composition-morphology-device performance relationships in conjugated polymer blends.

Unveiling Multiquantum Excitonic Correlations in Push-Pull Polymer Semiconductors.

Bound and unbound Frenkel-exciton pairs are essential transient precursors for a variety of photophysical and biochemical processes. In this work, we identify bound and unbound Frenkel-exciton complexes in an electron push-pull polymer semiconductor using coherent two-dimensional spectroscopy. We find that the dominant A peak of the absorption vibronic progression is accompanied by a subpeak, each dressed by distinct vibrational modes.

Enhancing composite electrode performance: insights into interfacial interactions.

Propelled by the widespread adoption of portable electronic devices, electrochemical energy storage systems, particularly lithium-ion batteries (LIBs), have become ubiquitous in modern society. The electrode is the critical battery component, where intricate interactions between the materials govern both the energy output and the overall lifespan of the battery under operational conditions. However, the poor interfacial properties of traditional electrode materials fall short in meeting escalating performance demands.

Exciton Bimolecular Annihilation Dynamics in Push-Pull Semiconductor Polymers.

Exciton-exciton annihilation is a ubiquitous nonlinear dynamic phenomenon in materials hosting Frenkel excitons. In this work, we investigate the nonlinear exciton dynamics of an electron push-pull conjugated polymer by fluence-dependent transient absorption and excitation-correlation photoluminescence spectroscopy, where we can quantitatively show the latter to be a more selective probe of the nonlinear dynamics. Simulations based on a time-independent exciton annihilation model show a decreasing trend for the extracted annihilation rates with excitation fluence.

Chain Conformation and Exciton Delocalization in a Push-Pull Conjugated Polymer.

Linear and nonlinear optical line shapes reveal details of excitonic structure in polymer semiconductors. We implement absorption, photoluminescence, and transient absorption spectroscopies in DPP-DTT, an electron push-pull copolymer, to explore the relationship between their spectral line shapes and chain conformation, deduced from resonance Raman spectroscopy and from calculations. The viscosity of precursor polymer solutions before film casting displays a transition that suggests gel formation above a critical concentration.

Carboxyl-Alkyl Functionalized Conjugated Polyelectrolytes for High Performance Organic Electrochemical Transistors.

Contemporary design principles for organic mixed ionic electronic conductors (OMIECs) are mostly based on the ethylene glycol moiety, which may not be representative of the OMIEC class as a whole. Furthermore, glycolated polymers can be difficult to synthesize and process effectively. As an emerging alternative, we present a series of polythiophenes functionalized with a hybrid carboxyl-alkyl side chain.

Conjugated Polymer Process Ontology and Experimental Data Repository for Organic Field-Effect Transistors.

Polymer-based semiconductors and organic electronics encapsulate a significant research thrust for informatics-driven materials development. However, device measurements are described by a complex array of design and parameter choices, many of which are sparsely reported. For example, the mobility of a polymer-based organic field-effect transistor (OFET) may vary by several orders of magnitude for a given polymer as a plethora of parameters related to solution processing, interface design/surface treatment, thin-film deposition, postprocessing, and measurement settings have a profound effect on the value of the final measurement.

Anisotropic Responsive Microgels Based on the Cholesteric Phase of Chitin Nanocrystals.

Anisotropic stimuli-responsive microgels based upon the cholesteric phase of chitin nanocrystals and -isopropylacrylamide were designed and synthesized. The cholesteric structure was interrogated, and the texture was shown to directly influence the microgel shape and anisotropy. Changes in the microgel volume led to changes in the texture, where microgels comprising up to six bands exhibited a twisted bipolar texture, while those with greater volumes displayed a concentric-packing structure.

The Solution is the Solution: Data-Driven Elucidation of Solution-to-Device Feature Transfer for π-Conjugated Polymer Semiconductors.

The advent of data analytics techniques and materials informatics provides opportunities to accelerate the discovery and development of organic semiconductors for electronic devices. However, the development of engineering solutions is limited by the ability to control thin-film morphology in an immense parameter space. The combination of high-throughput experimentation (HTE) laboratory techniques and data analytics offers tremendous avenues to traverse the expansive domains of tunable variables offered by organic semiconductor thin films.

Synergistic Effect of ,-Dimethylformamide and Hydrochloric Acid on the Growth of MAPbI Perovskite Films for Solar Cells.

Perovskite solar cells have emerged as a promising next-generation electrical power generating tool. However, imperfections in perovskite films are one of the crucial factors preventing the commercialization of perovskite solar cells. Passivation has proven to be an effective strategy to reduce the density of defect states in perovskite crystals and inhibit ion migration.

Integrated dynamic wet spinning of core-sheath hydrogel fibers for optical-to-brain/tissue communications.

Hydrogel optical light-guides have received substantial interest for applications such as deep-tissue biosensors, optogenetic stimulation and photomedicine due to their biocompatibility, (micro)structure control and tissue-like Young's modulus. However, despite recent developments, large-scale fabrication with a continuous synthetic methodology, which could produce core-sheath hydrogel fibers with the desired optical and mechanical properties suitable for deep-tissue applications, has yet to be achieved. In this study, we report a versatile concept of integrated light-triggered dynamic wet spinning capable of continuously producing core-sheath hydrogel optical fibers with tunable fiber diameters, and mechanical and optical propagation properties.

Ring-Patterned Perovskite Single Crystals Fabricated by the Combination of Rigid and Flexible Templates.

Regular microstructures can improve the electrical and optical characteristics of perovskite single crystals because of the removal of defects and grain boundaries. Microstructured single crystals are commonly fabricated by either rigid or flexible templates. However, rigid templates usually need surface treatment before crystal fabrication to create an antiadhesion layer, while flexible templates encounter difficulties in achieving a large area of uniform single crystals without any deformation.

Carboxylated Poly(thiophene) Binders for High-Performance Magnetite Anodes: Impact of Cation Structure.

While the focus of research related to the design of robust, high-performance Li-ion batteries relates primarily to the synthesis of active particles, the binder plays a crucial role in stability and ensures electrode integrity during volume changes that occur with cycling. Conventional polymeric binders such as poly(vinylidene difluoride) generally do not interact with active particle surfaces and fail to accommodate large changes in particle spacing during cycling. Thus, attention is now turning toward the exploration of interfacial interactions between composite electrode constituents as a key element in ensuring electrode stability.

Electrically Conductive Shell-Protective Layer Capping on the Silicon Surface as the Anode Material for High-Performance Lithium-Ion Batteries.

Rational design and construction of effective silicon (Si) electrode structures to relieve large volumetric changes that occur during the charge/discharge process remain significant challenges for the development of robust lithium-ion batteries (LIBs). Herein, we propose an electrically conductive poly[3-(potassium-4-butanoate)thiophene] (PPBT) capping layer on the Si surface (Si@PPBT) to serve as the active material and be used in conjunction with a common polymer binder as an approach to tackle issues emanating from volumetric changes. The PPBT protective shell layer provides the system with tolerance toward variations in active material volume during cycling, improves the dispersion of Si nanoparticles in the binder, enhances the electrolyte uptake rate, and provides a strong adhesion force between the Si/carbon additives/current collector, thereby helping to maintain electrode integrity during the charge/discharge process.

Control of Nucleation Density in Conjugated Polymers via Seed Nucleation.

The development of processing methods to precisely control the solution state properties of semiconducting polymers in situ have remained elusive. Herein, a facile solution seed nucleation processing method is presented in which nucleated poly(3-hexylthiophene) (P3HT) solutions are blended with well-solvated, non-nucleated counterparts as a means to promote the formation of interconnected polymer networks. Nucleation and growth of these networks was induced by preprocessing the solution with UV irradiation and subsequent solution aging prior to deposition via blade-coating.

Functionalized Cellulose Nanocrystal-Mediated Conjugated Polymer Aggregation.

Inducing the self-assembly of π-conjugated polymers into semicrystalline aggregates has been a topic of substantial interest in the field of organic electronics and is typically achieved using energy-intensive solution processing or postfilm deposition methods. Here, we demonstrate the ability of bioderived cellulose nanocrystals (CNCs) to act as structure-directing agents for the conjugated semiconducting polymer, poly(3-hexylthiophene) (P3HT). CNCs were grafted with polystyrene, P3HT or poly(-isopropylacrylamide), and subsequently blended with P3HT in solution to study the effect on conjugated polymer self-assembly.

Patterning Bubbles by the Stick-Slip Motion of the Advancing Triple Phase Line on Nanostructures.

The stick-slip motion of the triple phase contact line (TCL) has wide applications in inkjet printing, surface coatings, functional material assembly, and device fabrication. Here, for the first time, we report that on an alumina substrate with nanostructures, the stick-slip motion of the advancing TCL during spreading of an emulsion droplet can serve as an effective nanopatterning process. Air enclosed in the substrate nanostructures can be exchanged with liquid during the "stick" phase, resulting in the formation of bubbles arranged in a ring pattern.

A Polymer Blend Approach for Creation of Effective Conjugated Polymer Charge Transport Pathways.

Understanding the role of the distribution of polymer chain lengths on process-structure-property relationships in semiconducting organic electronics has remained elusive due to challenges in synthesizing targeted molecular weights ( M) and polydispersity indices. Here, a facile blending approach of various poly(3-hexylthiophene) (P3HT) molecular weights is used to investigate the impact of the distribution of polymer chain lengths on self-assembly into aggregates and associated charge transport properties. Low and high M samples were blended to form a highly polydisperse sample which was compared to a similar, medium M control.

Thermally Switchable Liquid Crystals Based on Cellulose Nanocrystals with Patchy Polymer Grafts.

A thermally "switchable" liquid-crystalline (LC) phase is observed in aqueous suspensions of cellulose nanocrystals (CNCs) featuring patchy grafts of the thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAM). "Patchy" polymer decoration of the CNCs is achieved by preferential attachment of an atom transfer radical polymerization (ATRP) initiator to the ends of the rods and subsequent surface-initiated ATRP. The patchy PNIPAM-grafted CNCs display a higher colloidal stability above the lower critical solution temperature (LCST) of PNIPAM than CNCs decorated with PNIPAM in a brush-like manner.