Solvent Vapor Annealing Treatment Research Articles

Lithium iodide transport in double gyroid nanochannels formed by zwitterion‐containing solid polymer electrolytes

AbstractThe fabrication of nanostructured block copolymer (BCP) films endowed with lithium ion‐conducting gyroid (GYR) nanochannels is an appealing solution to build solid polymer electrolytes (SPEs) that combines high ionic conductivity (IC) with suitable mechanical properties. However, the formation of a well‐developed GYR structure remains challenging to achieve from the self‐assembly of polyelectrolyte BCP chains. To overcome this issue, large ion conducting gyroid grains were produced within freestanding polystyrene‐block‐poly(2‐vinylpyridine)‐block‐poly(ethylene oxide) (PS‐b‐P2VP‐b‐PEO) films by combining a solvent vapor annealing (SVA) treatment with an infiltration process. Here, the SVA treatment enabled the manufacture of SPEs entirely composed of a GYR structure while the infiltration process allowed for the incorporation of an appropriate Li salt (i.e., lithium iodoacetate, LiIAc) within the 3D‐interconected nanochannels via a Menshutkin reaction. By using this SVA‐Infiltration strategy, it has been demonstrated that the creation of ion conducting GYR nanochannels enhances the ion transportation capacity of pyridine‐containing SPEs since substantially lower ICs were measured from analog PS‐b‐P2VP‐b‐PEO/LiIAc films having a nominally disordered as‐cast state. Remarkably, zwitterionic pyridinium‐based moieties formed inside the interpenetrated nanochannels enable an efficient migration of Li+ and I3− species, leading to an IC as high as 10−4 S cm−1 at 70°C.

Lithium iodide transport in double gyroid nanochannels formed by zwitterion‐containing solid polymer electrolytes

AbstractThe fabrication of nanostructured block copolymer (BCP) films endowed with lithium ion‐conducting gyroid (GYR) nanochannels is an appealing solution to build solid polymer electrolytes (SPEs) that combines high ionic conductivity (IC) with suitable mechanical properties. However, the formation of a well‐developed GYR structure remains challenging to achieve from the self‐assembly of polyelectrolyte BCP chains. To overcome this issue, large ion conducting gyroid grains were produced within freestanding polystyrene‐block‐poly(2‐vinylpyridine)‐block‐poly(ethylene oxide) (PS‐b‐P2VP‐b‐PEO) films by combining a solvent vapor annealing (SVA) treatment with an infiltration process. Here, the SVA treatment enabled the manufacture of SPEs entirely composed of a GYR structure while the infiltration process allowed for the incorporation of an appropriate Li salt (i.e., lithium iodoacetate, LiIAc) within the 3D‐interconected nanochannels via a Menshutkin reaction. By using this SVA‐Infiltration strategy, it has been demonstrated that the creation of ion conducting GYR nanochannels enhances the ion transportation capacity of pyridine‐containing SPEs since substantially lower ICs were measured from analog PS‐b‐P2VP‐b‐PEO/LiIAc films having a nominally disordered as‐cast state. Remarkably, zwitterionic pyridinium‐based moieties formed inside the interpenetrated nanochannels enable an efficient migration of Li+ and I3− species, leading to an IC as high as 10−4 S cm−1 at 70°C.

Responsive polymer thin films

Responsive polymer thin films

Square arrays of vertically aligned nanoporous cylinders from a linear ABC triblock terpolymer

AbstractVertically oriented nanoporous cylinders, demonstrating an unprecedented alignment persistence, were produced within freestanding poly(1,1‐dimethyl silacyclobutane)‐block‐polystyrene‐block‐poly(2‐vinyl pyridine) (PDMSB‐b‐PS‐b‐P2VP) layers (~15 μm thick) blended with short PS‐b‐P2VP chains by combining the non‐solvent induced phase separation (NIPS) process with a solvent vapor annealing (SVA) treatment. Here, the NIPS step allowed for the formation of an asymmetric and porous PDMSB‐b‐PS‐b‐P2VP film having a top surface exhibiting poorly‐defined nanopores while the subsequent SVA treatment enabled to produce a symmetric layer that possesses highly‐ordered cylindrical nanodomains arranged into a 27 nm period square array. As the unblended NIPS/SVA‐made PDMSB‐b‐PS‐b‐P2VP monoliths exhibited a mixed orientation of parallel and perpendicular cylinders, a blending strategy was used to achieve tetragonally‐packed PDMSB and P2VP nanodomains having an exceptional vertical alignment persistence. Such solvent‐annealed (3 h, CHCl3) PDMSB‐b‐PS‐b‐P2VP monoliths blended with 20 wt% of PS‐b‐P2VP chains showed a water permeance close to the value measured through their parent NIPS‐made terpolymer films having poorly‐ordered nanopores.

Effects of solvent vapor annealing on the optical properties and surface adhesion of conjugated D : A thin films.

A diketopyrrolopyrrole (DPP) and perylene diimide (PDI)-based molecule, denoted as PDI-DPP-PDI, was investigated as an electron acceptor material in bulk heterojunction (BHJ) solar cells, with poly[[4,8-bis [5-(2-ethylhexyl)-2-thienyl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl] [2-(2-ethyl-1-oxohexyl)thieno[3,4-b]thiophenediyl]] (PBDTTT-CT) as an electron donor. The donor polymer and the acceptor molecule have complementary absorption spectra, which is an essential feature for energy collection in organic solar cells. However, AFM images indicated the presence of isolated and microsized PDI-DPP-PDI domains along the surface of the films, which reduced the power conversion efficiency. Therefore, to improve the homogenization of the acceptor along the film, a post-deposition treatment, denoted as solvent vapor annealing (SVA), was performed in a saturated atmosphere containing the vapour of an organic solvent for 3-10 minutes. This procedure changed the optical and morphological properties of the PBDTTT-CT : PDI-DPP-PDI active layer, resulting in increased power conversion efficiency values by more than 2.5 times (reaching 5.1%). Theoretical simulation pointed out that the experimental absorbance band localized at 580 nm, which appeared after SVA treatment, is possibly related to an intense simulated band with a maximum at 572 nm, resulting from a pair of transitions starting in the copolymer and ending in PDI-DPP-PDI, in regions where both are stacked at about 3 Å. The most significant natural transition orbitals (NTOs) related to these transitions indicated charge transfer character. Moreover, analyses carried out by power spectrum density (PDS) of images acquired from the SVA-treated film indicated that in the region of larger frequencies, across the length scale at around 30-70 nm, an additional fractal region appeared with a Ds of 0.95, indicating a flattened region, possibly related to changes in the overall conformation after SVA treatment. This indicates an improvement in the molecular packing, a feature not observed in the as-cast film. The analyses by force curve spectroscopy pointed out increased adhesion forces and adhesion energy in the PBDTTT-CT : PDI-DPP-PDI film after SVA treatment; this feature enhanced the interfacial interaction with the top electrodes, reflecting improved charge extraction in the photovoltaic device.

Double stimuli‐responsive perforated lamellar structure formed by linear ABC triblock terpolymer monoliths

AbstractAmphiphilic block copolymer (BCP) thick films with stimuli‐responsive pores are promising candidates for the manufacturing of next‐generation ultrafiltration (UF) membranes since their smart nanochannels facilitates the removal of fouling which is considered as one of the biggest challenges in membrane technology. In this work, a well‐defined polystyrene‐block‐poly(2‐vinylpyridine)‐block‐poly(N‐isopropylacrylamide) (PS‐b‐P2VP‐b‐PNIPAM) terpolymer was prepared for the first time via reversible addition‐fragmentation chain transfer polymerization. The combination of the nonsolvent‐induced phase separation process with a solvent vapor annealing treatment was used to produce nanostructured pH‐ and thermo‐double sensitive ABC‐type BCP thick films. Here, the NIPS‐made PS‐b‐P2VP‐b‐PNIPAM thick film, comprising a microporous spinodal‐type network substructure, topped by a dense thin layer of poorly defined nanopores is transformed into a monolith entirely composed of a well‐ordered perforated lamellar (PL) phase upon exposure to a chloroform vapor during 6 h. Such kind of PL‐structured monoliths, showing a permeance value as high as 18 L h−1 m−2 bar−1 at 46°C and pH = 7 with an excellent temperature cyclability, are highly desired to manufacture smart separation‐based UF materials able to transit their pore state from hydrophilic to hydrophobic (and vice versa), thereby leading to much more efficient detachment of foulants during the cleaning process.

PTB7:PC71BM bulk heterojunction solar cells exhibiting 9.64% efficiency via adopting moderate polarity solvent vapor annealing treatment

The effects of solvent vapor annealing (SVA) with different polar solvents on the performances of polymer solar cell (PSCs) was systematically investigated by applying seven polar solvents, including methanol, acetone, chloroform, o-dichlorobenzene, chlorobenzene, toluene and n-hexane. A 9.64% of power conversion efficiency (PCE) was obtained in the PTB7:PC71BM based PSCs with conventional structure of ITO/PEDOT:PSS/PTB7:PC71BM/LiF/Al by employing the moderate polarity chlorobenzene-SVA method, corresponding to an approximate 21% enhancement in PCE relative to the PSCs without SVA. The enhanced PCEs of PSCs with active layers undergoing chlorobenzene-SVA process are mainly attributed to the combined advantages of the increased absorption intensity, the higher and more balanced carrier mobilities, the upper migration of the PC71BM, and the excellent donor/acceptor phase separation interface in the active layer. Our work not only demonstrates that polar solvent SVA treatment is a much more efficient method of improving the efficiency of PSCs without time-consuming and laborious fabrication procedures, but also provides some feasible reference for the application of different polar solvent SVA treatment in photovoltaic field.

Asymmetric Solvent-Annealed Triblock Terpolymer Thick Films Topped by a Hexagonal Perforated Lamellar Nanostructure.

Asymmetric and nanostructured polystyrene-block-poly(2-vinyl pyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO or SVEO, S:V:EO ≈ 56:34:10, 79.5kg mol-1 ) thick films blended with 20 wt% of a short PS homopolymer (hPS, 10.5kg mol-1 ) are achieved by combining the non-solvent induced phase separation (NIPS) process with a solvent vapor annealing (SVA) treatment. Here, the NIPS step allows for the formation of a highly-permeable sponge-like substructure topped by a dense thin layer exhibiting poorly-ordered nanopores while the subsequent SVA treatment enables to reconstruct the material top surface into a porous monolayer of well-ordered hexagonal perforated lamellae (HPL). This optimized film architecture generated by NIPS-SVA shows a water permeability of 860 L h-1 m-2 bar-1 , which is roughly two times higher than the flux measured through NIPS made PS-b-P2VP-b-PEO/hPS materials having poorly-ordered nanopores. The post-SVA treatment is also revealed as a powerful tool to tailor the thickness of the nanostructure formed within the blended material because monoliths entirely composed of a HPL phase are produced by increasing the time of exposure to a chloroform stream. The water flux of such PS-b-P2VP-b-PEO/hPS monoliths is found to be an order of magnitude lower than that of their asymmetric film homologues.

Alkyl-Side-Chain Engineering of Nonfused Nonfullerene Acceptors with Simultaneously Improved Material Solubility and Device Performance for Organic Solar Cells.

Two nonfullerene small molecules, TBTT-BORH and TBTT-ORH, which have the same thiophene–benzothiadiazole–thiophene (TBTT) core flanked with butyloctyl (BO)- and octyl (O)-substituted rhodanines (RHs) at both ends, respectively, are developed as electron acceptors for organic solar cells (OSCs). The difference between the alkyl groups introduced into TBTT-BORH and TBTT-ORH strongly influence the intermolecular aggregation in the film state. Differential scanning calorimetry and UV–vis absorption studies reveal that TBTT-ORH exhibited stronger molecular aggregation behavior than TBTT-BORH. On the contrary, the material solubility is greatly improved by the introduction of a BO group in TBTT-BORH, and the inevitably low molecular interaction and packing ability of the as-cast TBTT-BORH film can be effectively increased by a solvent-vapor annealing (SVA) treatment. OSCs based on the two acceptors and PTB7-Th as a polymer donor are fabricated owing to their complementary absorption and sufficient energy-level offsets. The best power conversion efficiency of 8.33% is obtained with the SVA-treated TBTT-BORH device, where, together with a high open-circuit voltage of 1.02 V, the charge-carrier mobility and the short-circuit current density were greatly improved by the SVA treatment to levels comparable to those of the TBTT-ORH device because of the suppressed charge recombination and improved film morphology. In this work, the simultaneous improvement of both material solubility and device performance is achieved through alkyl side-chain engineering to balance the trade-offs among material solubility/crystallinity/device performance.

Understanding the synergistic effect of mixed solvent annealing on perovskite film formation* *Project supported by the National Natural Science Foundation of China (Grant Nos. 21734009, 51473009, 21225209, 91427303, and 61805138). Portions of this research were carried out at beamline 7.3.3 at the Advanced Light Source, Molecular Foundry, Lawrence Berkeley National Laboratory, which was supported by the DOE, Office of Science,

Morphology control of perovskite films is of critical importance for high-performance photovoltaic devices. Although solvent vapor annealing (SVA) treatment has been widely used to improve the film quality efficiently, the detailed mechanism of film growth is still under construction, and there is still no consensus on the selection of solvents and volume for further optimization. Here, a series of solvents (DMF, DMSO, mixed DMF/DMSO) were opted for exploring their impact on fundamental structural and physical properties of perovskite films and the performance of corresponding devices. Mixed solvent SVA treatment resulted in unique benefits that integrated the advantages of each solvent, generating a champion device efficiency of 19.76% with improved humidity and thermal stability. The crystallization mechanism was constructed by conducting grazing-incidence wide-angle x-ray diffraction (GIWAXS) characterizations, showing that dissolution and recrystallization dominated the film formation. A proper choice of solvent and its volume balancing the two processes thus afforded the desired perovskite film. This study reveals the underlying process of film formation, paving the way to producing energy-harvesting materials in a controlled manner towards energy-efficient and stable perovskite-based devices.

Effect of organic solvent vapor treatment on transistor performance and contact resistance of copper phthalocyanine based organic field-effect transistors

In this study, we investigated the effect of organic solvent drop-casting and solvent vapor annealing (SVA) on the surface morphology of copper phthalocyanine (CuPc) thin film and its effect on contact resistance in organic field effect transistors (OFETs). Organic solvents: acetone and isopropyl alcohol (IPA) are used for drop-casting and SVA treatment of CuPc film. The morphology, crystallinity and optical properties of untreated and treated CuPc films are investigated through ultraviolet–visible (UV–Vis) absorption spectroscopy, X-ray diffraction (XRD) and atomic force microscopy (AFM). The results reveal that crystallinity and grain size increase in CuPc film treated with SVA. Large grain size results fewer grain boundaries forming better contact between source/drain (S/D) electrodes and the organic layer. As a result, the SVA treated CuPc based OFETs show one order increased charge carrier mobility and two order decreased contact resistance compared to that observed in untreated CuPc based OFET.

Synergistic Effect of Additive and Solvent Vapor Annealing on the Enhancement of MAPbI3 Perovskite Solar Cells Fabricated in Ambient Air.

To date, most high-performance perovskite solar cells (PSCs) are fabricated in an inert or vacuum condition to circumvent the moisture effect, which is one of the leading causes of sparse crystal nucleation and nonuniform morphology. Therefore, it is crucial to develop a simple approach to deposit a uniform and homogeneous perovskite on a planar substrate in ambient air for the mass production of PSCs. Herein, we investigated the synergistic effect of additive 1,8-diiodooctane (DIO) and solvent vapor annealing (SVA) treatments on the performance of PSCs fabricated in ambient air. It was found that the addition of 1 vol % DIO together with SVA treatment results in the enhancement of the perovskite film's crystallinity, grain size, and photophysical properties. PSCs containing 1 vol % DIO additive and SVA treatment exhibited a power conversion of efficiency (PCE) of 17.04%, which is markedly higher than the control device with a PCE of 10.61%. The results indicate that the additive DIO and SVA can work together to significantly improve the performance of PSCs fabricated in ambient air. This work provides a promising route for developing high-performance PSCs in the ambient environment.

Optical Alignment of Si-Containing Nanodomains Formed by Photoresponsive Amorphous Block Copolymer Thin Films

A series of amorphous block copolymers (BCPs), consisting of a low-glass-transition polydimethylsiloxane (PDMS) block associated with a photoresponsive azobenzene-containing poly(disperse red 1 methacrylate-co-alkyl methacrylate) (P(DR1MA-co-RMA)) block, were prepared from a PDMS macro-chain transfer agent used for the reversible addition–fragmentation chain-transfer (RAFT) copolymerization of binary mixtures of methacrylate monomers of various compositions. The resulting BCPs containing up to 40 wt % of azo dye exhibited low dispersity demonstrating a good control of the RAFT polymerization through the copolymerization of the DR1MA and RMA units. Long-range-ordered in-plane PDMS cylinders were produced by exposing the (as-cast) disordered BCP thin films to a p-polarized laser beam, to orthogonally align the azo groups with the polarization direction, prior to promoting the microphase separation of the BCP domains with a solvent vapor annealing treatment. Conversely, the photoinduced alignment of the azo ...

Rational Design of 2D p–π Conjugated Polysquaraines for Both Fullerene and Nonfullerene Polymer Solar Cells

AbstractSo far, squaraine‐based polymer donors have been less explored for the bulk heterojunction (BHJ) polymer solar cells. In this work, two new p–π conjugated polysquaraines (PASQ‐BDT1 and PASQ‐BDT2) with different electron‐rich subunits on the squaraine skeleton are rationally developed as new polymer donors based on the 2D structure design concept. PASQ‐BDT2 with N,N‐diisobutylaniline subunits shows superior device performances in both fullerene and nonfullerene PSCs compared to PASQ‐BDT1 containing triphenylamine subunits, with power conversion efficiencies (PCEs) of 4.34% and 3.72%, respectively, owing to increased light‐harvesting ability and more favorable nanoscale morphology in the BHJ films. Moreover, its demonstrated that solvent effects can play an effective role in elevating the device performance. For the PASQ‐BDT2/PC71BM blend, the PCE is improved from 3.19% to 4.34% after solvent vapor annealing treatment, mainly attributed to the optimized film morphology and increased hole mobility. More interestingly, when the processing solvent for nonfullerene devices is changed from chlorobenzene to chloroform, a significant enhancement on PCE from 1.96% to 3.72% is yielded for the PASQ‐BDT2/ITIC blend, due to suppressed charge recombination and enhanced crystallinity in the chloroform‐processed BHJ films.

Effectiveness of Solvent Vapor Annealing over Thermal Annealing on the Photovoltaic Performance of Non-Fullerene Acceptor Based BHJ Solar Cells

We explore two small molecules containing arms of dicyano-n-hexylrhodanine and diathiafulvalene wings terminated with benzothiadiazole linker, denoted as BAF-4CN and BAF-2HDT, respectively, as small molecule non-fullerene acceptors (SMNFAs) in organic solar cells. The proposed materials are mixed with a low band gap polymer donor PTB7-Th having broad absorption in the range of 400–750 nm to form solution-processed bulk heterojunctions (BHJs). The photoluminescence (PL) measurements show that both donor and acceptor can quench each other’s PL effectively, implying that not only electrons are transferred from PTB7-Th → SMNFAs but also holes are transferred from SMNFAs → PTB7-Th for efficient photocurrent generation. Furthermore, solvent vapor annealing (SVA) processing is shown to yield a more balanced hole and electron mobility and thus suppresses the trap-assisted recombination significantly. With this dual charge transfer enabled via fine-tuning of end-groups and SVA treatment, power conversion efficiency of approximately 10% is achieved, demonstrating the feasibility of the proposed approach.

Bicontinuous Network Nanostructure with Tunable Thickness Formed on Asymmetric Triblock Terpolymer Thick Films

Asymmetric poly(1,1-dimethyl silacyclobutane)-block-polystyrene-block-poly(2-vinyl pyridine) (PDMSB-b-PS-b-P2VP) thick films, consisting of a spongelike substructure topped by a nanostructured dense top layer, were produced by combining a fast self-assembly of the triblock terpolymer chains with nonsolvent-induced phase separation (referred as SNIPS). A controlled evolution of the thickness and morphology of the nanostructured top layer was achieved upon solvent vapor annealing (SVA). For instance, the sub-100 nm thick square array morphology generated by SNIPS is transformed into a 1.5 mu m thick core-shell perforated lamellar (PL) structure when exposed to a chloroform (CHCl3) vapor for 3 h. A PL phase having highly ordered continuous P2VP nanochannels can be envisioned as an appealing morphology for membrane applications, since such a network structure formed on asymmetric PDMSB-b-PS-b-P2VP thick films obviates the need for alignment. Monoliths entirely composed of the bicontinuous PL structure were also produced by increasing the duration of the SVA treatment (18 h, CHCl3)

Simple Bithiophene–Rhodanine‐Based Small Molecule Acceptor for Use in Additive‐Free Nonfullerene OPVs with Low Energy Loss of 0.51 eV

AbstractThe introduction of rigid and extended ladder‐type fused‐ring cores, such as indacenodithiophene, has enabled the synthesis of a variety of nonfullerene small molecules for use as electron acceptors in high‐performance organic photovoltaic cells. Contrasting with recent trends, a very simple‐structured nonfullerene acceptor (NFA), T2‐ORH, consisting of a bithiophene core and octyl‐substituted rhodanine ends, is synthesized in two steps from inexpensive commercially available raw materials. Its relatively short π‐conjugation results in a wide bandgap and a blue‐shifted UV–vis absorption profile complementary to those of poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐co‐3‐fluorothieno[3,4‐b]thiophene‐2‐carboxylate] (PTB7‐Th). Despite a sufficient offset between T2‐ORH and PTB7‐Th, the lowest unoccupied molecular orbital (LUMO) energy level of T2‐ORH is still higher than the LUMOs of other NFAs (e.g., ITIC). Therefore, the PTB7‐Th:T2‐ORH blend film exhibits an efficiency of 9.33% with a high open‐circuit voltage of 1.07 V and a short‐circuit current of 14.72 mA cm−2 in an additive‐free single‐junction cell. Importantly, the optimized device displays a remarkably low energy loss of 0.51 eV, in which bimolecular and monomolecular charge recombination is effectively suppressed by solvent vapor annealing treatment. The blend film has a very smooth and homogeneous morphology, providing both vertical and parallel charge transport in the devices.

Facile Preparation of Self-Assembled Polydopamine-Modified Electrospun Fibers for Highly Effective Removal of Organic Dyes.

Polydopamine (PDA) nanoparticles can be used as an adsorbent with excellent adsorption capacity. However, nanosized adsorbents are prone to aggregation and thus are severely limited in the field of adsorption. In order to solve this problem, we utilized polydopamine in-situ oxidation self-polymerization on the surface of polycaprolactone (PCL)/polyethylene oxide (PEO) electrospun fiber after solvent vapor annealing (SVA) treatment, and successfully designed and prepared a PCL/PEO@PDA composite membrane. The SVA treatment regulated the microscopic morphology of smooth PCL/PEO electrospun fibers that exhibited a pleated microstructure, increasing the specific surface area, and providing abundant active sites for the anchoring of PDA nanoparticles. The PCL/PEO@PDA composite obtained by chemical modification of PDA demonstrated numerous active sites for the adsorption of methylene (MB) and methyl orange (MO). In addition, the PCL/PEO@PDA composites were reusable several times with good reutilization as adsorbents. Therefore, we have developed a highly efficient and non-agglomerated dye adsorbent that exhibits potential large-scale application in dye removal and wastewater purification.

High-Crystallinity π-Conjugated Small Molecules Based on Thienylene-Vinylene-Thienylene: Critical Role of Self-Organization in Photovoltaic, Charge-Transport, and Morphological Properties.

Narrow-band-gap small molecules with π-extended backbones are promising donor materials for solution-processed bulk-heterojunction (BHJ) organic solar cells (OSCs). Herein, a series of acceptor-donor-acceptor (A-D-A) photovoltaic small molecules incorporating thienylene-vinylene-thienylene (TVT) as a central D unit and alkyl-substituted rhodanine or 2-(1,1-dicyanomethylene)rhodanine as terminal A units are designed and synthesized. Their physical properties including photoabsorption, electronic energy levels, hole mobility, and morphological characteristics are systematically investigated. Using solvent vapor annealing (SVA), the morphologies of the BHJ photoactive layers composed of these small-molecule donors and a [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) acceptor can be properly modulated. As a result of increased crystallinity of the donors and desired phase segregation between the donors and PC71BM upon rapid SVA treatment, the photovoltaic performances of the resultant OSC devices undergo drastic enhancement. The results reported here indicate that high-efficiency small-molecule OSCs can be achieved through rational design of the TVT-based molecular framework and optimization of the nanoscale phase-segregated morphology via proper SVA treatment.

Facile preparation and catalytic performance characterization of AuNPs-loaded hierarchical electrospun composite fibers by solvent vapor annealing treatment

A new ternary poly(ε-caprolactone) (PCL)/poly(ethylene oxide) (PEO)@AuNPs composite material with high catalytic activity and favorable structural stability has been successfully prepared. The prepared PCL/PEO composite fibers by electrospinning have been treated with an easy-to-operate solvent vapor annealing (SVA) process, demonstrating wrinkled fiber nanostructures, promoting the significantly high specific surface area and more active sites in the surface of electrospun fiber. Then NaBH4 was used as a reducing agent to reduce HAuCl4 to form gold nanoparticles, resulting in the targeted PCL/PEO@AuNPs composite material. The obtained PCL/PEO@AuNPs composites demonstrated potential catalytic ability and good reusability in the catalytic reduction of 4-nitrophenol and 2-nitroaniline systems, showing promising and wide applications in catalytic composite materials and self-assembled films.