Biowaste Eggshell Membranes for Bio-triboelectric Nanogenerators and Smart Sensors

In this study, we used a simple and cost-effective method to fabricate triboelectric nanogenerators (TENGs) based on biowaste eggshell membranes (EMs). We prepared stretchable electrodes with various types of EMs (hen, duck, goose, and ostrich) and employed them as positive friction materials for bio-TENGs. A comparison of the electrical properties of the hen, duck, goose, and ostrich EMs revealed that the output voltage of the ostrich EM could reach up to 300 V, due to its abundant functional groups, natural fiber structure, high surface roughness, high surface charge, and high dielectric constant. The output power of the resulting device reached 0.18 mW, sufficient to power 250 red light-emitting diodes simultaneously, as well as a digital watch. This device also displayed good durability when subjected to 9000 cycles at 30 N at a frequency of 3 Hz. Furthermore, we designed an ostrich EM-TENG as a smart sensor for the detection of body motion, including leg movement and the pressing of different numbers of fingers.

Reduced graphene oxide nanosheets decorated with core-shell of Fe3O4-Au nanoparticles for rapid SERS detection and hyperthermia treatment of bacteria

In this study, the core-shell of Fe₃O₄-Au nanoparticles (NPs) were prepared by seeding AuNPs onto Fe₃O₄ NPs modified with poly-ethylenimine (PEI). Later, Fe₃O₄-Au NPs were attached to cationic poly(dimethyldiallylammonium chloride) (PDDA)-modified graphene oxide (GO) nanosheets through in situ self-assembly behaviors, termed as Fe₃O₄-Au@RGO nanocomposites, for surface-enhanced Raman scattering (SERS) detection and hyperthermia treatment of bacteria. The resulting Fe₃O₄-Au@RGO nanocomposites were evaluated systematically by transmission electron microscope, zeta potential, X-ray diffraction, X-ray photoelectron spectroscopy, and vibrating sample magnetometer. It revealed that the core-shell structured Fe₃O₄-Au NPs were dispersed homogeneously on the surface of the GO nanosheets. Furthermore, the rapid SERS detection for small biomolecules and bacteria was conducted by Raman spectroscopy. The results showed that the greatest SERS intensity was fne tuned at the weight ratio of Fe₃O₄-Au/RGO nanosheets was 20/1, displaying the optimal interparticle gap of AuNPs to induce the huge hot-spots effect. The magnetic inductive heating capability of Fe₃O₄-Au@RGO nanocomposites was produced under high frequency magnetic field exposure and can kill high than 90% of the bacteria at 10 min. Hence, the newly developed Fe₃O₄-Au@RGO nanocomposites were demonstrated to be viable for SERS detection of biomolecules and microbes and potential applications for magnetically capturing and hyperthermia treatment of bacteria.

Intelligent and thermo-responsive Au-pluronic® F127 nanocapsules for Raman-enhancing detection of biomolecules

Thermo-responsive Raman-enhanced nanocapsules were successfully fabricated by Pluronic® F127 (F127) decorated with gold nanoparticles (AuNPs) for surface-enhanced Raman scattering (SERS) detection of biomolecules. F127 nanocapsules changes from hydrophilicity (swelling) to hydrophobicity (de-swelling) when the temperature increases from 15 °C to 37 °C, owing to the lower critical solution temperature (LCST) of F127 is about 26.5 °C. The size of nanocapsules would be enormous shrinking from 160 nm to 20 nm, resulting in a significant decrease in the distance between AuNPs to enhance hot spot effect, which increases the sensitivity of SERS detection. Based on the thermo-sensitive behavior, the ratio of AuNPs and F127 would be manipulated to find the optimal SERS enhancement effect. SERS nanocapsules can rapidly detect biomolecules (adenine and R6G) with limit of detection (LOD) lower than 10^-6 M. In addition, the relatively difficult to detect clinical samples, carboxyl-terminal parathyroid hormone fragments (C-PTH), can also be measured by the thermo-responsive SERS nanocapsules developed in this work. It is expected the biomolecules can be adsorbed at low temperature (15 °C), as well as collected and concentrated at high temperature (37 °C) for SERS detection, to increase the sensitivity and stability of SERS detection.

Naphthalene Diimide-Based Donor-Acceptor-Donor Small Molecules as Metal-Free Organocatalysts for Photocatalytic CO2 Reaction

The application of organic small molecules as metal-free photocatalysts for light-driven photoreduction of carbon dioxide (CO₂) has seldom been explored. This work developed four naphthalene diimide (NDI)-derived donor-acceptor-donor small molecules with different numbers of thiophene units, namely, NDI-2T, NDI-TT, NDI-4T, and NDI-6T, as metal-free photocatalysts to catalyze the reduction of CO₂ under irradiation with an air mass 1.5G solar simulator at one-sun intensity. The structure-property relationship was investigated by exploring the effects of the electron-donating ability of the donor units on the optical properties, redox potential, electron-hole distribution, and exciton lifetime. NDI-6T exhibited the most red-shifted absorption, longest exciton lifetime, and strongest electron-hole separation. However, the large upshift in oxidation potential because of the elevated electron-donating ability of the hexathiophene unit significantly reduced the driving force for catalyst regeneration, leading to poor catalytic performance. Alternatively, NDI-4T possessed proper redox potentials, reduced charge-transfer resistance, and excellent photocurrent intensity; therefore, it effectively converted CO₂ to a single product of CO in the presence of water as an electron donor without a sacrificial reagent or cocatalyst with a product yield of 168.6 μmol g_cat^-1 24 h^-1, which was considerably higher than those of NDI-TT (111.9 μmol g_cat^-1 24 h^-1), NDI-2T (88.4 μmol g_cat^-1 24 h^-1), and NDI-6T (40.5 μmol g_cat^-1 24 h^-1). This study provides a practical guideline for the molecular design of conjugated organic molecules as promising photocatalysts for CO₂ photoreduction.

Chromatic Fulleropyrrolidine as Long-Lived Metal-Free Catalyst for CO2 Photoreduction Reaction

Conversion of CO₂ into carbonaceous fuels with the aid of solar energy has been an important research subject for decades. Owing to their excellent electron-accepting capacities, fullerene derivatives have been extensively used as n-type semiconductors. This work reports that the fulleropyrrolidine functionalized with 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole, abbreviated as DTBT-C₆₀ , could efficiently catalyze the photoreduction of CO₂ to CO. The novel C₆₀ -chromophore dyad structure facilitated better usage of solar light and effective dissociation of excitons. Consequently, the DTBT-C₆₀ exhibited a promising CO yield of 144 μmol g_cat ^-1 under AM1.5G solar illumination for 24 h. Moreover, the isotope experiments demonstrated that water molecules could function as an electron source to reactivate DTBT-C₆₀ . Impressively, DTBT-C₆₀ exhibited an extremely durable catalytic activity for more than one week, facilitating the practical application of photochemical CO₂ reaction.

Sustainable Synthesis of Cyclic Carbonates from Terminal Epoxides by a Highly Efficient CaI2/1,3-Bis[tris(hydroxymethyl)-methylamino]-propane Catalyst

The nonstopping increment of atmospheric carbon dioxide (CO₂) concentration keeps harming the environment and human life. The traditional concept of carbon capture and storage (CCS) is no longer sufficient and has already been corrected to carbon capture, utilization, and storage (CCUS). CCUS involves significant CO₂ utilization, such as cyclic carbonate formation, for its cost effectiveness, less toxicity, and abundant C1 synthon in organic synthesis. However, the high thermodynamic and kinetic stability of CO₂ limits its applications. Herein, we report a mild, efficient, and practical catalyst based on abundant, nontoxic CaI₂ in conjunction with biocompatible ligand 1,3-bis[tris(hydroxymethyl)-methylamino]-propane (BTP) for CO₂ fixation under atmospheric pressure with terminal epoxides to give the cyclic carbonates. The Job plot detected the 1:1 Ca²⁺/BTP binding stoichiometry. Furthermore, formation of a single crystal of the 1:1 Ca²⁺/BTP complex was confirmed by single-crystal X-ray crystallography. The bis(cyclic carbonate) products exhibit potentials for components in the non-isocyanate polyurethanes (NIPUs) process. Notably, this protocol shows attractive recyclability and reusability.

Improved Blend Film Morphology and Free Carrier Generation Provide a High-Performance Ternary Polymer Solar Cell

Non-fullerene organic photovoltaics (OPVs) have displayed the highest power conversion efficiencies (PCEs) among OPVs. Herein, we describe a two-donor (PM6, TPD-3F)/one-acceptor (Y6) ternary blend having an optimized blend morphology that leads to improved OPV performance. Because TPD-3F has a HOMO energy level deeper than that of PM6, the value of V_OC of the corresponding ternary device increased. Good miscibility between PM6 and TPD-3F, in conjunction with device optimization through the use of 1-chloronaphthalene as an additive, provided an optimized ternary blend morphology for efficient exciton dissociation and carrier transport and, therefore, larger PCE. Compared with the preoptimized PM6:Y6 binary device, the ternary device functioned with improvements in its short-circuit current density, value of V_OC, and fill factor. As a result, the device PCE improved from 15.5 ± 0.19 to 16.6 ± 0.25% under AM 1.5G (100 mW cm^-2) irradiation. The champion cell exhibited a PCE of 17.0%-a value that is one of the highest for a ternary OPV. Furthermore, such devices exhibited outstanding shelf lifetimes, with long-term stability in air (25 °C, 40% humidity) without encapsulation; the performance remained high (at 15.4%) after storage for 820 h.

Design of Thienothiophene-Based Copolymers with Various Side Chain-End Groups for Efficient Polymer Solar Cells

Three two-dimensional donor-acceptor conjugated copolymers consisting of a benzo[1,2-b:4,5-b']dithiophene derivative and thieno[3,2-b]thiophene with a conjugated side chain were designed and synthesized for use in bulk heterojunction (BHJ) or nonfullerene polymer solar cells (PSCs). Through attaching various acceptor end groups to the conjugated side chain on the thieno[3,2-b]thiophene moiety, the electronic, photophysical, and morphological properties of these copolymers were significantly affected. It was found that the intermolecular charge transfer interactions were enhanced with the increase in the acceptor strength on the thieno[3,2-b]thiophene moiety. Moreover, a better microphase separation was obtained in the copolymer: PC71BM or ITIC blend films when a strong acceptor end group on the thieno[3,2-b]thiophene moiety was used. As a result, BHJ PSCs based on copolymer:PC71BM blend films as active layers exhibited power conversion efficiencies from 2.82% to 4.41%, while those of nonfullerene copolymer:ITIC-based inverted PSCs ranged from 6.09% to 7.25%. These results indicate the side-chain engineering on the end groups of thieno[3,2-b]thiophene unit through a vinyl bridge linkage is an effective way to adjust the photophysical properties of polymers and morphology of blend films, and also have a significant influence on devices performance.

High-Performance Semitransparent Organic Photovoltaics Featuring a Surface Phase-Matched Transmission-Enhancing Ag/ITO Electrode

In this study, we designed a surface phase-matched transmission enhancement top electrode-Ag/indium tin oxide (ITO) structure for highly efficient and aesthetic semitransparent organic photovoltaics (ST-OPVs). The purposed highly transparent back electrodes (Ag/ITO) could selectively decrease visible reflection and increase transparency accordingly. By altering the thicknesses of the Ag and ITO layers, we could control the transmittance curve and increase the transparency of the ST-OPV devices. Devices based on PTB7-Th:IEICO-4F and PM6:Y6:PC₇₁BM displayed outstanding performance (8.1 and 10.2%, respectively) with high photopic-weighted visible light transmittance (36.2 and 28.6%, respectively). The outstanding visible and near-infrared light harvesting of PM6:Y6:PC₇₁BM further allowed a new application: double-sided energy harvesting from solar and indoor illumination. The simple optical design of a top electrode displaying high transparency/conductivity has a wide range of potential applications in, for example, greenhouse photovoltaics, tandem cells, and portable devices.

Commercially available jeffamine additives for p-i-n perovskite solar cells

Commercially available Jeffamines (polyetheramine) with average molecular weights of 2000 and 3000 g mol^-1; one (M2005), two (D2000), and three (T3000) primary amino groups end-capping on the polyether backbone; and propylene oxide (PO) and ethylene oxide (EO) functionality were explored as additives for application in MAPbI₃ perovskite solar cells (PSCs). The results indicated that the embedding of Jeffamine additives effectively passivates the defects in the grain boundaries of perovskite through the coordination bonding between the nitrogen atom and the uncoordinated lead ion of perovskite. We fabricated p-i-n PSC devices with the structure of glass/indium tin oxide (ITO)/NiO_x/CH₃NH₃PbI₃ (with and without Jeffamine)/PC₆₁BM/BCP/Ag. We observed the interaction between the Jeffamine and perovskites. This interaction led to increased lifetimes of the carriers of perovskite, which enabled the construction of high-performance p-i-n PSCs. For the Jeffamine-D2000-derived device, we observed an increase in the power conversion efficiency from 14.5% to 16.8% relative to the control device. Furthermore, the mechanical properties of the perovskite films were studied. The interaction between the additive and perovskite reinforced the flexibility of the thin film, which may pave the way for stretchable optoelectronics.

A Near-Infrared Absorption Small Molecule Acceptor for High-Performance Semitransparent and Colorful Binary and Ternary Organic Photovoltaics

An acceptor-donor-acceptor (A-D-A)-type non-fullerene acceptor (NFA), PTTtID-Cl, featuring thieno[3,2-b]thieno[2''',3''':4'',5'']-pyrrolo[2'',3'':4',5']thieno[2',3':4,5]thieno-[2,3-d]pyrrole (DTPTt) as the electron-rich core and 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (ID-Cl) as the peripheral electron-deficient terminal group was synthesized and characterized. PTTtID-Cl exhibited strong absorption in the range of 700-850 nm in CHCl₃ and redshifted absorption centered at 881 nm in a thin film. The near infrared (NIR)-absorption of PTTtID-Cl was combined with a low-bandgap polymer donor (PTB7-Th) to achieve binary and semitransparent organic photovoltaics (OPVs) with a power conversion efficiency (PCE) of 8.9 % and 7.7 % (with an average visible transmittance (AVT) of 16.7 %), respectively. A ternary device with a ratio of PM7/PTTtID-Cl/IT-4F=1:0.15:0.85 (w/w) achieved a short-circuit current density of 19.46 mA cm^-2 , an open-circuit voltage of 0.87 V, and a fill factor of 71.2 %, giving a PCE of 12.0 %. In addition, by employing the Ag/ITO/Ag microcavity structure, semitransparent colorful binary organic photovoltaics (OPVs) with superior transparency of 27.9 % at 427 nm and 22.7 % at 536 nm for blue and green devices, respectively, were prepared. The semitransparent colorful devices based on the optimized ternary blend gave PCEs of 8.7 %, 8.4 %, and 9.1 % for blue, green, and red devices, respectively. These results indicate the promising potential of PTTtID-Cl as a NIR-absorption NFA for applications in semitransparent colorful binary and ternary OPVs.

Evaluation of Carbon Dioxide-Based Urethane Acrylate Composites for Sealers of Root Canal Obturation

A new root canal sealer was developed based on urethane acrylates using polycarbonate polyol (PCPO), a macrodiol prepared in the consumption of carbon dioxide as feedstock. The superior mechanical properties and biostability nature of PCPO-based urethane acrylates were then co-crosslinked with a difunctional monomer of tripropylene glycol diarylate (TPGDA) as sealers for resin matrix. Moreover, nanoscale silicate platelets (NSPs) immobilized with silver nanoparticles (AgNPs) and/or zinc oxide nanoparticles (ZnONPs) were introduced to enhance the antibacterial effect for the sealers. The biocompatibility and the antibacterial effect were investigated by Alamar blue assay and LDH assay. In addition, the antibacterial efficiency was performed by using Enterococcus faecalis (E. faecalis) as microbial response evaluation. These results demonstrate that the PCPO-based urethane acrylates with 50 ppm of both AgNP and ZnONP immobilized on silicate platelets, i.e., Ag/ZnO@NSP, exhibited great potential as an antibacterial composite for the sealer of root canal obturation.

Synthesis and Properties of Cyclopentyl Cardo-Type Polyimides Based on Dicyclopentadiene

A crucial polymer intermediate, 4-[1-(4-hydroxyphenyl)cyclopentyl]-phenol (bisphenol CP), was developed from dicyclopentadiene (DCPD), a key byproduct of the C5 fraction in petrochemicals. On the basis of bisphenol CP, a diamine, 4,4'-((cyclopentane-1,1-diylbis(4,1-phenylene))bis(oxy))-dianiline (cyclopentyl diamine; CPDA) was subsequently obtained through a nucleophilic substitution of bisphenol CP, followed by the hydrogenation process. By using the CPDA diamine, a series of polyimides with cyclopentyl (cardo) units on the backbone were prepared along with a reference polyimide (API-6F) based on 4,4'-(4,4'-(propane-2,2-diyl)bis(4,1-phenylene))bis(oxy)dianiline (BPAA), and 4,4'-(hexafluoroisopropylidene)-diphthalic anhydride (6FDA) for the exploration of structure-properties relationship. Thanks to the presence of cyclopentyl units, this type of cardo polyimides exhibited comparable tensile properties, especially a large elongation (25.4%). It is also worth noting that CPI-6F exhibited better solubility in organic solvents, such as NMP, DMAc, THF, and chloroform, than the other PIs. Gas separation properties were also evaluated for these cardo-type polyimides.

In Search of a Green Process: Polymeric Films with Ordered Arrays via a Water Droplet Technique

As an efficient technique for the preparation of polymeric hexagonal orderly arrays, the breath figure (BF) process has opened a modern avenue for a bottom-up fabrication method for more than two decades. Through the use of the water vapor condensation on the solution surface, the water droplets will hexagonally pack into ordered arrays, acting as a template for controlling the regular micro patterns of polymeric films. Comparing to the top-down techniques, such as lithography or chemical etching, the use of water vapor as the template provides a simple fabrication process with sustainability. However, using highly hazardous solvents such as chloroform, carbon disulfide (CS2), benzene, dichloromethane, etc., to dissolve polymers might hinder the development toward green processes based on this technique. In this review, we will touch upon the contemporary techniques of the BF process, including its up-to-date applications first. More importantly, the search of greener processes along with less hazardous solvents for the possibility of a more sustainable BF process is the focal point of this review.

Synthesis of Surfactant-Free and Morphology-Controllable Vanadium Diselenide for Efficient Counter Electrodes in Dye-Sensitized Solar Cells

In this study, a transition-metal selenide, vanadium diselenide (VSe₂), with various morphologies was synthesized by employing a surfactant-free hydrothermal method under varied temperature conditions (190-220 °C). Although the physical properties of VSe₂ have been studied before, only limited morphological change or application were explored. This study, for the first time, applied VSe₂ as the electrocatalytic counter electrode (CE) in dye-sensitized solar cells (DSSCs) and showed an attractive cell efficiency. The mechanism of forming the tunable VSe₂ morphologies is proposed. The evaluation of solar cell efficiency shows the correlation between morphology and electrocatalytic properties. It was further shown that VSe₂-200 with the cauliflower-like morphology shows the highest cell performance of DSSC with an efficiency of 9.23 ± 0.07% under 1 sun irradiance, superior to that of the Pt-based DSSC (8.48 ± 0.08%). An electrochemical technique equipped with a rotating disk electrode system was introduced to confirm the high electrocatalytic performance with this particular morphology. The optimized VSe₂ demonstrated good long-term stability with 78% retention after 500 cycles of the consecutive cyclic voltammetry, compared to 60% for the Pt CE. The control in morphology in vanadium diselenide synthesis and its usage in Pt-free CE DSSC have advanced the progress in electrochemistry.

Si-Bridged Ladder-Type Small-Molecule Acceptors for High-Performance Organic Photovoltaics

In this study, we synthesized 5,11-dihexyl-4,4,10,10-tetraoctylbenzo[1,2- b:4,5- b']bisthieno[4″,5″- b″:4‴,5‴- b‴]silolo[2″,3″- d:2‴,3‴- d']thiophene (ArSi) as a ladder-type electron-rich core for the preparation of three acceptor-donor-acceptor-type nonfullerene acceptors (NFAs)-ArSiID, ArSiID-F, and ArSiID-Cl-featuring (3-oxo-2,3-dihydro-1 H-inden-1-ylidene)malononitrile (ID), 2-(5,6-difluoro-3-oxo-2,3-dihydro-1 H-inden-1-ylidene)malononitrile (ID-F), and 2-(5,6-dichloro-3-oxo-2,3-dihydro-1 H-inden-1-ylidene)malononitrile (ID-Cl) as peripheral electron-poor units, respectively. These molecules exhibit strong absorption covering the region of 600-850 nm. The incorporation of the halogen atoms onto the terminal units adjusted the energy levels and light-harvesting ability of these materials. We employed the conjugated polymers J51 and PBDB-T, having middle optical energy gaps as donor together with these ArSi derivatives as acceptor to study the blend film morphology and the corresponding organic photovoltaic (OPV) performances. After optimization with device engineering works, a PBDB-T:ArSiID-F-based device with a power conversion efficiency up to 9.4% was achieved. This study is the first case to examine the effects of various halogen modifications on the performance of ArSi derivatives that serve as NFAs for OPVs. Our findings should encourage further investigations on this rarely studied core structure for optoelectronic applications.

Novel Multifunctional Luminescent Electrospun Fluorescent Nanofiber Chemosensor-Filters and Their Versatile Sensing of pH, Temperature, and Metal Ions

Novel multifunctional fluorescent chemosensors composed of electrospun (ES) nanofibers with high sensitivity toward pH, mercury ions (Hg2+), and temperature were prepared from poly(N-Isopropylacrylamide-co-N-methylolacrylamide-co-rhodamine derivative) (poly(NIPAAm-co-NMA-co-RhBN2AM)) by employing an electrospinning process. NIPAAm and NMA moieties provide hydrophilic and thermo-responsive properties (absorption of Hg2+ in aqueous solutions), and chemical cross-linking sites (stabilization of the fibrous structure in aqueous solutions), respectively. The fluorescent probe, RhBN2AM is highly sensitive toward pH and Hg2+. The synthesis of poly(NIPAAm-co-NMA-co-RhBN2AM) with different compositions was carried on via free-radical polymerization. ES nanofibers prepared from sensory copolymers with a 71.1:28.4:0.5 NIPAAm:NMA:RhBN2AM ratio (P3 ES nanofibers) exhibited significant color change from non-fluorescent to red fluorescence while sensing pH (the λPL, max exhibited a 4.8-fold enhancement) or Hg2+ (at a constant Hg2+ concentration (10-3 M), the λPL, max of P3-fibers exhibited 4.7-fold enhancement), and high reversibility of on/off switchable fluorescence emission at least five times when Hg2+ and ethylenediaminetetraacetic acid (EDTA) were sequentially added. The P3 ES nanofibrous membranes had a higher surface-to-volume ratio to enhance their performance than did the corresponding thin films. In addition, the fluorescence emission of P3 ES nanofibrous membranes exhibited second enhancement above the lower critical solution temperature. Thus, the ES nanofibrous membranes prepared from P3 with on/off switchable capacity and thermo-responsive characteristics can be used as a multifunctional sensory device for specific heavy transition metal (HTM) in aqueous solutions.

A star-shaped conjugated molecule featuring a triazole core and diketopyrrolopyrrole branches is an efficient electron-selective interlayer for inverted polymer solar cells

A novel triazole-cored, star-shaped, conjugated molecule (TDGTPA) has been synthesized for use as an electron-selective interlayer in inverted polymer solar cells (PSCs). This star-shaped molecule comprised a triazole unit as the central core, 2,5-thienyl diketopyrrolopyrrole units as π-conjugated bridges, and tert-butyl-substituted triphenylamine units as both end groups and donor units. The inverted PSC had the device structure indium tin oxide/ZnO/TDGTPA/poly(3-hexylthiophene) (P3HT)/fullerene derivative (PC₇₁BM)/MoO₃/Ag. Inserting TDGTPA as the electron-selective layer enhanced the compatibility of the ZnO-based electron transport layer and the P3HT:PC₇₁BM blend-based photoactive layer. The low energy of the lowest unoccupied molecular orbital (−3.98 eV) of TDGTPA was favorable for electron transfer from the photoactive layer to the ZnO layer, thereby enhancing the photovoltaic performance of the PSC. The photo-conversion efficiency of the device incorporating TDGTPA as the electron-selective layer was 15.8% greater than that of the corresponding device prepared without it.

A novel triazole-cored, star-shaped, conjugated molecule (TDGTPA) has been synthesized for use as an electron-selective interlayer in inverted polymer solar cells (PSCs).

Embedding a Diketopyrrolopyrrole-Based Cross-linking Interfacial Layer Enhances the Performance of Organic Photovoltaics

In this study, we prepared DPPBTDA, a diketopyrrolopyrrole-based small molecule presenting a terminal cross-linkable azido group, as a cathode modifying layer for organic photovoltaics (OPVs) having the inverted device structure glass/indium tin oxide/zinc oxide (ZnO) with or without the interfacial layer (IFL)/active layer/MoO₃/Ag. The active layer comprising a blend of poly[4,8-bis(5-(2-ethylhexyl)thien-2-yl)benzo[1,2- b;4,5- b']dithiophene-2,6-diyl- alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4- b]thiophene)-2-carboxylate-2,6-diyl] (PTB7-Th) as the electron donor and [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) as the electron acceptor. Atomic force microscopy, space-charge-limited current mobility, surface energy, electron spectroscopy for chemical analysis depth profile, ultraviolet photoelectron spectroscopy analysis, and OPV performance data revealed that the surface status of ZnO changed after inserting the DPPBTDA/PCBM hybrid IFL and induced an optimized blend morphology, having a preferred gradient distribution of the conjugated polymer and PC₇₁BM, for efficient carrier transport. The power conversion efficiency (AM 1.5 G, 1000 W m^-2) of the device incorporating the hybrid IFL increased to 9.4 ± 0.11% from 8.5 ± 0.15% for the preoptimized PTB7-Th/PCBM device (primarily because of an enhancement in the fill factor from 68.7 ± 1.1 to 72.1 ± 0.8%).

Au Nanoparticles Immobilized on Honeycomb-Like Polymeric Films for Surface-Enhanced Raman Scattering (SERS) Detection

We have successfully developed novel surface-enhanced Raman scattering (SERS) substrates with three-dimensional (3D) porous structures for effectively improving the sensitivity and reproducibility of SERS, which can rapidly detect small molecules (rhodamine 6G as an example). Periodical arrays of the honeycomb-like substrates were fabricated by self-assembling polyurethane-co-azetidine-2,4-dione (PU-PAZ) polymers. PU-PAZ comprising amphiphilic dendrons could stabilize the phase separation between the water droplets and polymer solution, and then organize into regular porous structures during the breath figure method. Subsequently, SERS substrates were fabricated by immobilizing gold nanoparticles (AuNPs) onto the honeycomb-like films with various 3D porous structures, controlled by the different PU-PAZ concentrations and relative humidities. Results show that surface enhancement factors of honeycomb-like substrates were 20 times higher than that of flat-film substrates (control group) due to enormous hot-spots resonance effects by the 3D porous structure, verified through Raman mapping at various positions of the z-axis. Furthermore, the particle size effects were evaluated by immobilized 12 and 67 nm of AuNPs on the honeycomb-like substrates, indicating larger AuNPs could induce more pronounced hot-spots effects. The generation of hot-spots resonance to enhance Raman intensity is strongly dependent on the diameter of AuNPs and the pore size of the honeycomb-like and 3D porous substrates for label-free and rapid SERS detection.

Synthesis of di(ethylene glycol)-functionalized diketopyrrolopyrrole derivative-based side chain-conjugated polymers for bulk heterojunction solar cells

Synthesis of diketopyrrolopyrrole derivatives based side-chain conjugated polymers for solar cells.

Environment-noise-free optical heterodyne retardation measurement using a double-pass acousto-optic frequency shifter

We demonstrate an environment-noise-free optical heterodyne interferometer (OHI) based on a double-pass acousto-optic frequency shifter (AOFS) for phase retardation measurements. The OHI generates intermediate-frequency (IF) heterodyne beat signals for each orthogonal linear polarization mode of a birefringence sample. The phase differences of the IF signals are compared by using a wide-bandwidth lock-in amplifier. This scheme provides 20 dB rejection of common-mode environmental disturbances. Measurements of the half-wave voltage of an electro-optics modulator and the electro-optic coefficient of an LiNbO₃ plate are demonstrated as application examples.

Insight into the mechanism and outcoupling enhancement of excimer-associated white light generation

Fundamental insight into excimer formation of Cz⁹PhAn, achieving a single-component, high-performance WOLED.

Fundamental insight into excimer formation has been gained by using 9,10-bis[4-(9-carbazolyl)phenyl]anthracene] (Cz⁹PhAn) as a probe. Cz⁹PhAn exhibits a highly emissive blue fluorescence in solution and is found to emit a panchromatic white light spectrum (400–750 nm) in film, powder and single crystal, in which an additional excimer band appears at ∼550 nm. Detailed structural analyses, emission relaxation dynamics and a theoretical approach conclude the formation of an anthracene*/phenyl ring excimer through an overlap between π* (anthracene) and π (phenyl ring) orbitals in a face-to-edge stacking orientation. The rate of excimer formation is determined to be 2.2 × 10⁹ s^–1 at room temperature, which requires coupling with lattice motion with an activation energy of 0.44 kcal mol^–1. Exploiting Cz⁹PhAn as a single emitter, a fluorescent white organic light emitting diode (WOLED) is fabricated with a maximum external quantum efficiency (η_ext) of 3.6% at 1000 cd m^–2 (4.2 V) and Commission Internationale de L'Eclairage (CIE) coordinates of (0.30, 0.33). The white-light Cz⁹PhAn reveals a preferred orientation of the transition dipole moment in the emitting layer to enhance light outcoupling. This non-doped, single component (Cz⁹PhAn) WOLED greatly reduces the complexity of the fabrication process, rendering a green and cost-effective alternative among the contemporary display/lighting technologies.

MoS2-Gd Chelate Magnetic Nanomaterials with Core-Shell Structure Used as Contrast Agents in in Vivo Magnetic Resonance Imaging

Despite their frequent usages as contrast agents for in vivo MRI imaging, paramagnetic molecules continue to suffer from low resolution, physicochemical instability, and high toxicity. Herein, we present a molybdenum disulfide and gadolinium complex, as an alternative core-shell magnetic nanomaterial that exhibits enhanced paramagnetic property; 4.5-times longer water proton spin-lattice relaxation time (T1) when compared to commercial gadolinium contrast agents; as well as lowered toxicity, extended blood circulation time, increased stability, and desirable excretion characteristic. Transmission electron microscopy (TEM) revealed smooth core-shell nanoparticles 100 nm in size with a shell width of approximately 10 nm. These findings suggest that the synthesized nanomaterial possesses high potential as a positive contrast agent for the enhancement of MRI imaging.

Tailored honeycomb-like polymeric films based on amphiphilic poly(urea/malonamide) dendrons

A series of hydrogen bond-rich poly(urea/malonamide) dendrons were utilized as surfactants to facilitate the formation of honeycomb-like porous structures from the breath figure (BF) process.

Fabrication of Gold Nanoparticles/Graphene-PDDA Nanohybrids for Bio-detection by SERS Nanotechnology

In this research, graphene nanosheets were functionalized with cationic poly (diallyldimethylammonium chloride) (PDDA) and citrate-capped gold nanoparticles (AuNPs) for surface-enhanced Raman scattering (SERS) bio-detection application. AuNPs were synthesized by the traditional citrate thermal reduction method and then adsorbed onto graphene-PDDA nanohybrid sheets with electrostatic interaction. The nanohybrids were subject to characterization including X-ray diffraction (XRD), transmission electron microscopy (TEM), zeta potential, and X-ray photoelectron spectroscopy (XPS). The results showed that the diameter of AuNPs is about 15-20 nm immobilized on the graphene-PDDA sheets, and the zeta potential of various AuNPs/graphene-PDDA ratio is 7.7-38.4 mV. Furthermore, the resulting nanohybrids of AuNPs/graphene-PDDA were used for SERS detection of small molecules (adenine) and microorganisms (Staphylococcus aureus), by varying the ratios between AuNPs and graphene-PDDA. AuNPs/graphene-PDDA in the ratio of AuNPs/graphene-PDDA = 4:1 exhibited the strongest SERS signal in SERS detection of adenine and S. aureus. Thus, it is promising in the application of rapid and label-free bio-detection of bacteria or tumor cells.

Enhanced photovoltaic performance of inverted polymer solar cells by incorporating graphene nanosheet/AgNPs nanohybrids

A linear-dendritic block copolymer functionalized exfoliated graphene nanosheets/silver nanoparticles was prepared for using as the interfacial layer between the electron-selective layer and photoactive layer in an inverted polymer solar cell.

Enhanced shape memory performance of polyurethanes via the incorporation of organic or inorganic networks

A diol compound with a reactive azetidine-2,4-dione group was prepared and introduced as a side chain moiety of poly(ε-caprolactone) (PCL) based polyurethane (PU).

Polythiophenes Comprising Conjugated Pendants for Polymer Solar Cells: A Review

Polythiophene (PT) is one of the widely used donor materials for solution-processable polymer solar cells (PSCs). Much progress in PT-based PSCs can be attributed to the design of novel PTs exhibiting intense and broad visible absorption with high charge carrier mobility to increase short-circuit current density (J_sc), along with low-lying highest occupied molecular orbital (HOMO) levels to achieve large open circuit voltage (V_oc) values. A promising strategy to tailor the photophysical properties and energy levels via covalently attaching electron donor and acceptor pendants on PTs backbone has attracted much attention recently. The geometry, electron-donating capacity, and composition of conjugated pendants are supposed to be the crucial factors in adjusting the conformation, energy levels, and photovoltaic performance of PTs. This review will go over the most recent approaches that enable researchers to obtain in-depth information in the development of PTs comprising conjugated pendants for PSCs.

Highly concentrated MoS2 nanosheets in water achieved by thioglycolic acid as stabilizer and used as biomarkers

Synthesis of water soluble MoS₂ quantum dots from the monolayer nanosheets of MoS₂, using thioglycolic acid (TGA) was reported in this study. TGA molecules not only exfoliated the bulk of MoS₂, but also modified the hydrophobic surface of MoS₂ with hydrophilic carboxylic acid groups.