Solution-processed Approach Research Articles

Fully Atom-Efficient Solvent-Mediated Biopolymer Manufacturing: A Base Case Illustrated with Macromolecular Surfactants Tailored to Stable Polymer-Water Interfaces.

This work introduces a novel 1-pot, 0-waste, 0-VOC methodology for synthesizing polymeric surfactants using acrylated epoxidized soybean oil and acrylated glycerol as primary monomers. These macromolecular surfactants are synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, allowing for tunable hydrophilic-lipophilic balance (HLB) and ionic properties. We characterize the copolymers' chemical composition and surface-active properties, and evaluate their effectiveness in forming and stabilizing emulsions of semiepoxidized soybean oil and poly(acrylated epoxidized high oleic soybean oil). Comprehensive analyses, including gel permeation chromatography, nuclear magnetic resonance spectroscopy, dynamic light scattering, particle size distribution, zeta potential, and critical micelle concentration, provide detailed insights into the copolymers and the emulsions they form. The results demonstrate that the RAFT-polymerized surfactants offer long-lasting stability and effectively disperse both common oil-in-water emulsions and highly viscous and hydrophobic polymer latexes. These surfactants outperform traditional small molecule surfactants by reducing particle size and preventing phase separation, even over extended storage periods. Stable polymer-water interfaces are achieved through HLB control, tailored by monomer composition, and the final product requires no additional purification since polymerization occurs in liquid surfactants. While small molecules contribute to rapid micelle formation, the polymeric components enhance long-term stability through steric repulsion and slower dynamics. This method enables even the emulsification of polymers with submicron particle size, which ordinarily requires emulsion polymerization. Integrating biobased polymeric surfactants with advanced polymer processing techniques opens new possibilities for transforming highly hydrophobic polymers into latexes, facilitating downstream applications. This innovation enhances the environmental sustainability of surfactant production and broadens the potential for polymer emulsification technologies. Additionally, the integrated solution-processing approach demonstrated here can be applied to other emerging polymers, where judiciously selected nonvolatile solvents facilitate the polymerization and play a role in the final application.

Salt-Assisted, In Situ Current Nanowelding of an Interfacial Au Nanoparticle Film for a High-Performance Electrocatalyst.

Interfacial self-assembly is a well-established method for the preparation of a two-dimensional (2D) metal nanofilm from nanoscale building blocks. However, the as-prepared nanofilm exhibits limited conductivity because of the large contact resistance at the junctions among its building blocks. Here, we report a salt-assisted, in situ current nanowelding strategy to weld an interfacial Au nanoparticle (NP) film for downstream applications, such as high-performance electrocatalysts. Particularly, we found that salt-assisted interfacial assembly can reduce the size of the nanogaps among neighboring Au NPs and, in turn, greatly improve the conductivity of the resultant Au NP film. Consequently, the Au NP film can be readily welded using current, and the welding extent can be monitored in real-time by looking at the passing current. The welding finally produces a nanoporous Au film (NPGF) with a network nanostructure, high conductivity, and abundant active sites so that it delivers a large current density of 86.96 μA·cm-2 (1.81 times higher than that from the pristine Au NP film) and shows improved cycling stability for methanol electrooxidation. Thus, these results offer a low-cost, solution-processable approach for the fabrication of a large-area, interconnected nanofilm from nanoscale building blocks beyond Au NPs, which may find diverse downstream applications.

Manipulating the diffusion energy barrier at the lithium metal electrolyte interface for dendrite-free long-life batteries.

Constructing an artificial solid electrolyte interphase (SEI) on lithium metal electrodes is a promising approach to address the rampant growth of dangerous lithium morphologies (dendritic and dead Li0) and low Coulombic efficiency that plague development of lithium metal batteries, but how Li+ transport behavior in the SEI is coupled with mechanical properties remains unknown. We demonstrate here a facile and scalable solution-processed approach to form a Li3N-rich SEI with a phase-pure crystalline structure that minimizes the diffusion energy barrier of Li+ across the SEI. Compared with a polycrystalline Li3N SEI obtained from conventional practice, the phase-pure/single crystalline Li3N-rich SEI constitutes an interphase of high mechanical strength and low Li+ diffusion barrier. We elucidate the correlation among Li+ transference number, diffusion behavior, concentration gradient, and the stability of the lithium metal electrode by integrating phase field simulations with experiments. We demonstrate improved reversibility and charge/discharge cycling behaviors for both symmetric cells and full lithium-metal batteries constructed with this Li3N-rich SEI. These studies may cast new insight into the design and engineering of an ideal artificial SEI for stable and high-performance lithium metal batteries.

Realization of future neuro-biological architecture in power efficient memristors of Fe3O4/WS2 hybrid nanocomposites

The future generation of digital technology will heavily rely on power efficient non-volatile resistive memory systems as a potential alternative to flash memory due to its limitations in scalability and endurance. To attain the commercial benchmark, memristors have still lacked performance. This study reports a novel and cost-effective solution processable method for growing surface-modified hybrid nanocomposites (Nc) on a large scale, as an active layer. The solution-processed synthesis approach used for Ag/Fe50W50/Pt hybrid nanocomposite memristor device results in the formation of heterophase grain boundaries, which create residual filaments along these boundaries. The device Fe3O4-WS2(Nc) shows excellent performance, having ultra-low energy consumption (0.1fJ), high reproducibility (10 devices), scalability, excellent endurance (106), and excellent environment stability. Density functional theory (DFT) simulations reveal that structural symmetry distortion and interfacial interaction of hybrid nanocomposite at the interface plays a vital role in the switching mechanism. As high-performance electronic synapses, the optimal pulse scheme enables a steady interaction of short- and long-term plasticity principles, such as spike -time dependent plasticity (STDP) and pulse pair facilitation (PPF), essential for learning and neuromorphic computing analogous to human brain. Moreover, by using Modified National Institute of Standards and Technology (MINST), the memristor device attained a high learning accuracy of 95.4% under convolution neural network (CNN) simulations. The present study revealed that the performance of hybrid-nanocomposite memristors could lead to efficient future neuromorphic architecture.

Efficient solution-processed fluorescent OLEDs realized by removing charge trapping emission loss of BODIPY fluorochrome.

The thermally activated delayed fluorescence (TADF)-sensitized fluorescent (TSF) dye strategy has been used successfully in thermally evaporated organic light-emitting diodes (eOLEDs), but the development of solution-processed TSF-OLEDs (TSF-sOLEDs) is still very limited to date. Previously, the introduction of electronically inert shielding terminal groups for TADF sensitizer and/or fluorescent dyes was commonly used in TSF-sOLEDs, which aimed to achieve sufficient Förster energy transfer (FET) while restraining notorious Dexter energy transfer (DET) at a high doping concentration of fluorescent dyes. However, this approach has not yet enabled efficient TSF-sOLEDs owing to severe charge trapping emission (CTE) for triplet loss. In this study, by simply utilizing highly efficient boron-dipyrromethene derivatives (BODIPYs) that simultaneously feature high fluorescent quantum efficiency and narrow-band emission spectra, we developed highly efficient and super color-purity TSF-sOLEDs using a 0.1 wt% ultralow doping strategy. As confirmed, the resultant ultralow doping TSF-sOLEDs achieved sufficient FET from sensitizer to fluorochrome without noticeable CTE issues. The device achieves record maximum external quantum efficiency (EQEmax) and current efficiency (CEmax) of 21.5% and 78.8 cd A-1, respectively, and an ultrapure green emission with Commission International de l'Eclairage (CIE) coordinates of (0.28, 0.65). This study validates the new device architecture of ultralow doping TSF-sOLEDs, which paves the way for future development of high-resolution TSF-sOLED displays via a simple solution-processed manufacturing approach.

Surface modification of medical grade biomaterials by using a low-temperature-processed dual functional Ag-TiO2 coating for preventing biofilm formation.

Biofilm development in medical devices is considered the major virulence component that leads to increased mortality and morbidity among patients. Removing a biofilm once formed is challenging and frequently results in persistent infections. Many current antibiofilm coating strategies involve harsh conditions causing damage to the surface of the medical devices. To address the issue of bacterial attachment in medical devices, we propose a novel antibacterial surface modification approach. In this paper, we developed a novel low-temperature based solution-processed approach to deposit silver nanoparticles (Ag NPs) inside a titanium oxide (TiO2) matrix to obtain a Ag-TiO2 nanoparticle coating. The low temperature (120 °C)-based UV annealed drop cast method is novel and ensures no surface damage to the medical devices. Various medical-grade biomaterials were then coated using Ag-TiO2 to modify the surface of the materials. Several studies were performed to observe the antibacterial and antibiofilm properties of Ag-TiO2-coated medical devices and biomaterials. Moreover, the Ag-TiO2 NPs did not show any skin irritation in rats and showed biocompatibility in the chicken egg model. This study indicates that Ag-TiO2 coating has promising potential for healthcare applications to combat microbial infection and biofilm formation.

Phase-Change Memory from Molecular Tellurides.

Phase-change memory (PCM) is an emerging memory technology based on the resistance contrast between the crystalline and amorphous states of a material. Further development and realization of PCM as a mainstream memory technology rely on innovative materials and inexpensive fabrication methods. Here, we propose a generalizable and scalable solution-processing approach to synthesize phase-change telluride inks in order to meet demands for high-throughput material screening, increased energy efficiency, and advanced device architectures. Bulk tellurides, such as Sb2Te3, GeTe, Sc2Te3, and TiTe2, are dissolved and purified to obtain inks of molecular metal telluride complexes. This allowed us to unlock a wide range of solution-processed ternary tellurides by the simple mixing of binary inks. We demonstrate accurate and quantitative composition control, including prototype materials (Ge-Sb-Te) and emerging rare-earth-metal telluride-doped materials (Sc-Sb-Te). Spin-coating and annealing convert ink formulations into high-quality, phase-pure telluride films with preferred orientation along the (00l) direction. Deposition engineering of liquid tellurides enables thickness-tunable films, infilling of nanoscale vias, and film preparation on flexible substrates. Finally, we demonstrate cyclable and non-volatile prototype memory devices, achieving performance indicators such as resistance contrast and low reset energy on par with state-of-the-art sputtered PCM layers.

Solution-Processed Hydrogen-Bonded Organic Framework Nanofilms for High-Performance Resistive Memory Devices.

The integration of hydrogen-bonded organic frameworks (HOFs) into electronic devices holds great promise due to their high crystallinity, intrinsic porosity, and easy regeneration. However, despite their potential, the utilization of HOFs in electronicdevices remains largely unexplored, primarily due to the challenges associated with fabricating high-quality films. Herein, a controlled synthesis of HOFnanofilms with smooth surface, good crystallinity, and high orientation is achieved using a solution-processed approach. The memristors exhibit outstanding bipolar switching performance with alow set voltage of 0.86V, excellent retention of 1.64 × 104 s, and operational endurance of 60 cycles. Additionally, these robust memristors display remarkable thermal stability, maintaining their performance even at elevated temperatures of up to 200 °C. More strikingly, scratched HOFfilms can be readily regenerated through a simple solvent rinsing process, enabling their reuse for the fabrication of new memristors, which is difficult to achieve with traditional resistive switching materials. Additionally, a switching mechanism based on the reversible formation and annihilation of conductive filaments is revealed. This work provides novel and invaluable insights that have a significant impact on advancing the widespread adoption of HOFs as active layers in electronic devices.

Electron-hole asymmetric magnetotransport of graphene-colloidal quantum dot device

Interfacing graphene with other low-dimensional material has gained attentions recently due to its potential to stimulate new physics and device innovations for optoelectronic and electronic applications. Here, we exploit a solution-processed approach to introduce colloidal quantum dot (CQD) to the bilayer graphene device. The magnetotransport properties of the graphene device is drastically altered due to the presence of the CQD potential, leading to the observation of AB-like oscillation in the quantum Hall regime and screening of the intervalley scattering. The anomalous magnetotransport behavior is attributed to the coulombic scattering introduced by the CQDs and is shown to be highly asymmetric depending on the polarity of the transport carriers. These results prove the potential of such flexible method for engineering microscopic scattering process and performance of the graphene device that may lead to intriguing device application in such hybrid system.

Synergetic Monitoring of both Physiological Pressure and Epidermal Biopotential Based on a Simplified on-Skin-Printed Sensor Modality.

Flexible electronic sensors show great potential for health monitoring but are usually limited to single sensing functionality. To enrich their functions, complicated device configurations, sophisticated material systems, and preparation processes are typically involved, obstructing their large-scale deployment and widespread application. Herein, to achieve a good balance between simplicity and multifunctionality, a new paradigm of sensor modality for both mechanical sensing and bioelectrical sensing is presented based on a single material system and a simple solution processing approach. The whole multifunctional sensors are constructed with a pair of highly conductive ultrathin electrodes (WPU/MXene-1) and an elastic micro-structured mechanical sensing layer (WPU/MXene-2), with the human skin serving as the substrate for the whole sensors. The resultant sensors show high pressure sensitivity and low skin-electrode interfacial impedance, enabling to synergetically monitor both physiological pressure (e.g., arterial pulse signals) and epidermal bioelectrical signals (including electrocardiograph and electromyography). The universality and extensibility of this methodology to construct multifunctional sensors with different material systems are also verified. This simplified sensor modality with enhanced multifunctionality provides a novel design concept to construct future smart wearables for health monitoring and medical diagnosis.

Nanoscale-Thick CuPc/β-Ga2O3 p–n Junctions for Harsh-Environment-Resistant Self-Powered Deep-UV Photodetectors

Due to their crucial role in ultraviolet communication and monitoring, deep-ultraviolet (DUV) photodetectors have garnered much interest. Recently, Ga2O3 has emerged as the best material for DUV photodetectors because of its ultrawide bandgap (4.5–4.9 eV), excellent UV photon absorption coefficient, high structural stability, and affordability. However, there are several difficulties in realizing high-performance Ga2O3-based DUV photodetectors with a high tolerance for harsh environments. In this work, nanoscale-thick CuPc/β-Ga2O3 p–n junctions were used to build high-performance DUV photodetectors by a straightforward solution-processing approach. The p–n junction photodetectors exhibit improved photoelectric performance compared to a single device made of β-Ga2O3 or CuPc, with a photo-to-dark current ratio of 3700 and a fast response time of ∼20 ms under a bias of 0 V. Due to the excellent stability of the nanoscale-thick CuPc film, the device can maintain a high photocurrent even at high temperatures or under long-term DUV irradiation. Our work provides an effective strategy toward highly harsh-environment-resistant DUV photodetectors.

Combinative solution processing and Li doping approach to develop p-type NiO thin films with enchanced electrical properties

The deposition of nickel oxide (NiOx) thin film from an acetylacetonate source using many solution-based techniques has been avoided owing to its poor solubility in alcohol solvents. From this perspective, this work provides a systematic investigation of the development of NiOx thin film, using a combinative approach of ultrasonic spray pyrolysis (USP) and Li dopant for the synthesis and optimization of structural and optoelectronic properties of the films. An in-depth comparative analysis of nickel acetylacetonate-based precursor, employing acetonitrile and methanol as solvents, is provided. It is demonstrated that USP from acetylacetonate precursor yielded uniform, well-compact, and transparent films, with polycrystalline cubic NiOx crystal structures. By screening the deposition temperature in the range of 300–450°C, a temperature of 400°C was identified as an optimal processing temperature leading to uniform, compact, highly transparent, and p-type conductive films. At optimized deposition conditions (400°C), lithium-doped NiOx (Li:NiOx) thin film was deposited. The shift of the main (200) XRD peak position from 43.48° (0-Li:NiOx) to 43.56° (60-Li:NiOx) indicated Li incorporation into the NiOx lattice. An X-ray photoelectron spectroscopy (XPS) study was employed to unravel the incorporation of Li into the deposited Li:NiOx thin films. With the deconvolution of the Ni 2p core level for the as-deposited (0, 60)-Li:NiOx films, the intensity of Ni3+ related peak was found to increase slightly with Li doping. Furthermore, all the deposited Li:NiOx thin films showed p-type conductivity behavior, and the resistivity was reduced from 104 Ωcm (0-Li:NiOx) to 102 Ωcm (60-Li:NiOx). Based on these results, the deposited NiOx and Li:NiOx thin films suggested that USP-deposited Li:NiOx is highly suitable for application in inverted structure solar cells as the hole transport layer.

Unraveling the Defect-Dominated Broadband Emission Mechanisms in (001)-Preferred Two-Dimensional Layered Antimony-Halide Perovskite Film

By adding molar-controlled SbCl3 in a Cs3Sb2Cl9 precursor, we employed a low-temperature solution-processed approach to prepare high-quality (001)-preferred Cs3Sb2Cl9 thin film, which demonstrates a stable defect-dominated broadband emission at room temperature. Density functional theory calculations reveal that the defect emission originates from the donor-acceptor pair (DAP) recombination between chlorine vacancy (VCl) and cesium vacancy (VCs). Furthermore, VCl + VCs DAP is more stable on the (001) surface. The improved film quality and the more stable VCl + VCs DAP increase the activation energy related to defect states, resulting in an enhancement of the defect emission for the high-quality (001)-preferred film. This work provides deep insight into the key role of the (001) surface in defect emission and a feasible strategy to enhance the defect emission in 2D halide perovskites A3B2X9 (A = CH3NH3, Cs, Rb; B = Bi, Sb; X = Cl, Br, I) by control of the thin film preferred orientation.

Synthesis and investigation of solution-processed Bi-doped Cu2ZnSn(S, Se)4 thin-film solar cells

Surface morphology plays a crucial role in influencing the film quality and photoelectric conversion efficiency (PCE) of a Kesterite Cu 2 ZnSn(S, Se) 4 (CZTSSe) solar cell. Herein, the bismuth (Bi) doping strategy to improve the surface morphology of the solution-processed CZTSSe film for high solar cell efficiency is reported. With a two-step selenization strategy to facilitate the Bi-doped CZTSSe (CZTBiSSe) phase formation, improving the crystalline quality of the absorber, increasing the carrier mobility, and reducing the band tailing, a cell efficiency of 6.94% has been achieved. These results demonstrate the significance of Bi doping into CZTSSe to improve the device's performance. This work offers new insights into the effects of Bi doping on CZTSSe via a solution-processed approach and provides a deeper understanding of the origin of the efficiency improvement of Bi-doped CZTSSe thin film solar cells. • A new method to improve Voc and PCE of CZTSSe solar cell by Bi doping is put forward. • This is the first report on solution-processed CZTBiSSe using two-step selenization. • This study shows hopeful character of Bi in increasing the Voc of CZTSSe solar cell. • Bi doping can improve crystal quality and decrease Sn Zn antisite defect states. • It is proved that Bi-doped CZTSSe is a promising band-gap tunable absorption layers.

Impact of Sb-insertion on structural, optical, and dielectric characteristics of the PbI2 thin film

Antimony (Sb) has been widely used as an additive in solar cells for enhanced performance. We described a simple, affordable, solution-processed approach for producing pure and antimony (Sb3+)-doped lead iodide (PbI2) thin films with varying doping ratios (0.5, 1.0, 2.0, and 3.0%). Structural, optical, and dielectric properties were investigated using XRD and UV–Vis spectroscopy. The XRD spectra illustrated that the synthesized PbI2 thin films have a preferred orientation along the c-axis (001) with a hexagonal structure. The crystalline sizes of PbI2 increased by increasing the Sb-doping concentration up to 1%, then decreased with 2% and 3% Sb-doping. In the visible and NIR regions, the optical transparency of the grown films were in between 70 and 80%. The optical band gap changes inversely with the crystalline sizes; it decreases with 0.5% and 1% Sb-doping and increases with further doping. As the energy gap is spanned between 2.39 and 2.27 eV, therefore, Sb: PbI2 films are ideal for use in solar cells. The resulting refractive index values were found to rise as the Sb doping concentration increased. Sb-doping decreases optical conductivity and dielectric constant.

Single-crystal organometallic perovskite optical fibers.

Semiconductors in their optical-fiber forms are desirable. Single-crystal organometallic halide perovskites have attractive optoelectronic properties and therefore are suitable fiber-optic platforms. However, single-crystal organometallic perovskite optical fibers have not been reported before due to the challenge of one-directional single-crystal growth in solution. Here, we report a solution-processed approach to continuously grow single-crystal organometallic perovskite optical fibers with controllable diameters and lengths. For single-crystal MAPbBr3 (MA = CH3NH3+) perovskite optical fiber made using our method, it demonstrates low transmission losses (<0.7 dB/cm), mechanical flexibilities (a bending radius down to 3.5 mm), and mechanical deformation–tunable photoluminescence in organometallic perovskites. Moreover, the light confinement provided by our organometallic perovskite optical fibers leads to three-photon absorption (3PA), in contrast with 2PA in bulk single crystals under the same experimental conditions. The single-crystal organometallic perovskite optical fibers have the potential in future optoelectronic applications.

Improving efficiency and stability of perovskite solar cells by SiO2 layer incorporation

A hydrophobicity silicon dioxide (SiO 2 ) layer inserting in perovskite and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) interface to form PEDOT:PSS/SiO 2 composite films. The formed hydrophobicity SiO 2 films fabricated by a new and easy solution-process approach with a chemical reaction by sodium silicate. The PEDOT:PSS/SiO 2 films present good transmittance and outstanding surface morphology. The SiO 2 films also slow down CH 3 NH 3 PbI 3 perovskite degradation, as well as promote charge carrier collection and reduce charge carrier recombination, what leads to high efficiency and excellent stability of the device. The 5 mg/mL SiO 2 based CH 3 NH 3 PbI 3 devices present a superior power conversion efficiency of 16% with an improved short-circuit current density of 20.31 mA/cm 2 and a considerable fill factor of 76.3% compared to the pure PEDOT:PSS based CH 3 NH 3 PbI 3 devices. Moreover no obvious hysteresis and good reproducibility was reported for devices based on the 5 mg/mL SiO 2 . The 5 mg/mL SiO 2 -based CH 3 NH 3 PbI 3 device shows remarkable stability, which shows that 90% of the initial efficiency remains after 140 days at room temperature. The devices based on CH 3 NH 3 PbI 3-x Cl x perovskite film also be fabricated by using PEDOT:PSS (with or without 5 mg/mL SiO 2 ), the CH 3 NH 3 PbI 3-x Cl x device based on PEDOT:PSS/SiO 2 transporting layer also shows superior performance, this result verify the universality of PEDOT:PSS/SiO 2 transporting layer. • A new and easy solution-process approach forming PEDOT:PSS/SiO 2 composite films with the chemical reaction of Na 2 SiO 3 . • The SiO 2 films slow down perovskite degradation, as well as promote charge carrier collection and reduce charge carrier recombination. • The 5 mg/mL SiO 2 based devices present a superior power conversion efficiency of 16% compared to the pure PEDOT:PSS based devices with an average power conversion efficiency of 13.5%. • The 5 mg/mL SiO 2 -based device reached remarkable stability, it was shown that 90% of the initial efficiency remains after 140 days at room temperature.

One-Step Patterning of Organic Semiconductors on Gold Electrodes via Capillary-Bridge Manipulation.

Patterning organic semiconductors directly on Au electrodes possesses the advantages of eliminating metal atomic penetration effect, compatibility with fine lithography processes, and feasibility of work function modification on electrodes, and it is therefore of value in the commercial manufacturability application of optoelectronic devices with low cost, large scale, and high efficiency. Solution processing, is relatively inexpensive and is scalable to large areas. Nonetheless, conventional solution processing approaches have trade-offs among controllable morphology, regular alignment, precise position, and ordered molecular packing arising from the uncontrollable dewetting kinetics. Here, one-step patterning of 1D polymer nanowire arrays directly on Au source-drain electrodes with precise position, controlled orientation, regulated distribution, and tunable width size were realized by employing a capillary-bridge manipulation method to guide the processes of liquid dewetting and nanowire assembly. Organic field-effect transistors (OFETs) with mobility of 10.1 cm2 V-1 s-1 and on/off current ratio of 1.9 × 104 were fabricated. Moreover, we verified generality of our method by patterning different solution-processable optoelectronic materials, including small molecules, quantum dot (QD) nanoparticles, and metal-halide perovskites, into ordered structures directly on the target substrate. The work provides a novel insight into efficient manufacturing the regular aligned and precisely positioned 1D organic semiconductors directly on the channel region of prefabricated Au electrodes in one step and facilitates their applications in high-performance electronic devices.

Recent Advances in Realizing Highly Aligned Organic Semiconductors by Solution-Processing Approaches.

Solution-processing approaches are widely used for controlling the aggregation structure of organic semiconductors because they are fast, efficient, and have strong practicability. Effective regulation of the aggregation structure of molecules to achieve highly ordered molecular stacking is key to realizing effective carrier transport and high-performance devices. Numerous studies have achieved highly aligned organic semiconductors using different solution-processing approaches. This article provides a detailed review of the prevalent solution-processing technologies and emerging methods developed over the past few years for the alignment of organic semiconducting materials. These technologies and methods are classified according to the processing principle. This review focuses on the principles of different experimental techniques, improvements upon the conventional methods, and state-of-the-art performance of resulting devices. In addition, a brief discussion of the characteristics and development prospects of various methods is presented.

Sequential polymer infusion into solid substrates (SPISS): Impact of processing on sorbent CO2 adsorption properties

Solid sorbents made of small amine molecules and polyamines infused into mesoporous substrates are promising materials for CO2 capture technologies. To date, their preparation is mainly based on wet infusion with focus on increasing amine content by varying the structure of the amine sorbent and designing solid substrates of various pore parameters. Less explored in the field are changes in processing to afford efficient CO2 sorbents. In this study, branched poly(ethylenimine) (bPEI, Mw = 800 Da) alone and blends with linear poly(propylenimine) (LPPI, Mn = 6,700 Da) are infused into solid SBA-15 substrates by a method that varies the solution processing called sequential polymer infusion into solid substrates (SPISS). The reference 40 % bPEI-SBA-15 samples are split by two methods: split batch in dry suspension (SBD) and split batch in liquid suspension (SBL). Sequentially, alcoholic 10% of bPEI (non-blends) and 10% of LPPI (blends) solutions are introduced to afford the desired products. Under dry conditions, the resulting 50% bPEI-SBA-15 SBD & SBL sorbents display high CO2 capacities up to 3.47 mmol CO2/gSiO2 for simulated flue gas (10% CO2) and 2.62 mmol CO2/gSiO2 for direct air capture (DAC, 400 ppm CO2). Under humid DAC conditions the CO2 performance is further enhanced with an uptake of 4.62 mmol CO2/gSiO2 and amine efficiency of 0.22 mmol CO2/mmol N. Subjected to extended temperature swing adsorption kinetic cycling (20 cycles), the SPISS samples display stable working capacities and retain over 70% (blends) and over 90% (non-blends) of their initial 12 h adsorption performance. LPPI is demonstrated to be an effective water sorption limiting agent using dynamic vapor sorption measurements. Solid state NMR techniques reveal important insights into the dynamics of the amine polymers confined into SBA-15 pores, as impacted by processing conditions. The results suggest that the conformation of the polymers is different depending on the processing method, displaying relatively tight (SBD) and loose (SBL) packing. The simple solution processing approaches presented here show that processing variations may guide the design of solid amine sorbents with desirable properties relevant for integration into CO2 capture technologies.