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A multifunctional modified layer (DPPTPTA@CuCoP/CNF) was used for the first time in dye-sensitized solar cells, which achieved a conversion efficiency of 25.44 at 6000 lux and ensured long-term stability (90% retention after 3000 h).

In this paper we describe three indacenodithiophene-based conjugated polymers (PITIC-Ph, PITIC-Th, and PITIC-ThF) that we tested as third components for PM6:Y6-based ternary organic photovoltaics (OPVs) to provide high-power conversion efficiencies (PCEs) and long-term thermal stabilities. Among them, the incorporation of PITIC-Ph enhanced the charge dissociation and prohibited the bimolecular (trap-assisted) recombination of the PM6:Y6 blend. Compared with the pre-optimized OPV device, the PCEs of the PITIC-Ph-doped devices improved from 15.0 ± 0.37 to 17.0 ± 0.35% under AM 1.5 G (100 mW cm−2) irradiation. More critically, studies of the thermal stability revealed another phenomenon: embedding PITIC-Ph decreased the degree of thermally driven phase segregation of the PM6:Y6 blend film. The respective OPVs exhibited outstanding thermal stability under stress at 150 °C within a glove box, with the PCE of the PITIC-Ph-doped device remaining high (at 16.4%) after annealing for 560 h.

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.

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.

Conjugated polyelectrolytes (CPEs) have developed as promising hole transport materials for perovskite solar cells (PSCs). The conjugated backbone serves as an efficient vehicle for transporting holes, and the electric dipole layer formed through the organization of ionic groups on CPEs may improve the hole collection efficiency. In this work, three CPEs anchored with –N(CH3)3+, –SO3− and –NH3+ ions, denoted as BF-NMe3, BF-SO3 and BF-NH3, respectively, were synthesized and applied as the hole transport material (HTM) of inverted planar PSCs. Replacing the benchmark material, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), with the three CPEs as the HTM considerably improves the photovoltaic performance of PSCs. The results from scanning electron microscope imaging, X-ray diffraction and time-resolved photoluminescence indicate that the structure of the ionic species rather than the type of charge has a decisive impact on the perovskite morphology. Both cationic BF-NH3 and anionic BF-SO3 layers enable methylammonium lead iodide (MAPbI3) to grow into larger crystals and grains with fewer defects. Moreover, the electrochemical impedance spectroscopy measurements demonstrate that the BF-NH3 and BF-SO3 devices have comparable charge recombination resistance, which is apparently higher than that of the BF-NMe3 and PEDOT:PSS devices. Consequently, the cationic BF-NH3 can act as an excellent HTM as the anionic BF-SO3 and the champion cell based on BF-NH3 exhibits a superior power conversion efficiency of 17.7%.

A series of new metal-free organic dyes based on 3,3′-dithioalkyl-2,2′-bithiophene (SBT) organic chromophores was synthesized for use in dye-sensitized solar cells (DSSCs). Because S(alkyl)⋯S(thiophene) intermolecular interlocking renders the twist angle in the structure as

Arrays of 20 nm silver nanoparticles (AgNPs) with tunable interparticle gaps have been grown on mesoporous silica (MPS) nanospheres to form AgNPs@MPS nanohybrids for surface-enhanced Raman scatteri...

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 conditi...

We have successfully prepared a floating-typed surface-enhanced Raman scattering (SERS) substrate by the uniform nanoparticle arrays of silver nanoparticles (AgNPs) immobilized on the dendron-exfoliated reduced graphene oxide (rGO) nanosheets. These poly(urea/malonamide) dendrons were precisely synthesized, and then grafted on the dendron-exfoliated rGO nanosheets based on an efficient building block of dual functional 4-isocyanato-4′-(3,3-dimethyl-2,4-dioxo-azetidino)-diphenylmethane (IDD). By using dendron-rGO nanosheets as templates for hosting AgNPs, the particle size (D) and interparticle gap (W) of AgNPs could be manipulated by the incorporation of dendrons of various generations (0.5, 1.5, and 2.5 generations), evaluated by transmission electron microscopy. The results indicate that the nanohybrids with 1.5 generation-dendron exhibited stable, enormous, and linear-quantitative Raman enhancement in malachite green detection (1–100 ppm), due to the lowest W/D ratio (0.85 ± 0.60) and interparticle gap (7.60 ± 5.29 nm). The limit of detection (LOD) of malachite green is lower than 2.7 × 10−11 M (0.01 ppb). AgNPs@rGO-dendritic derivative nanohybrids as floating and flexible SERS substrates provide ultrasensitive and stable SERS detection in the solutions, which offers great potential for practical applications in detecting environmental pollutants.

Three two-dimensional donor&ndash, acceptor conjugated copolymers consisting of a benzo[1,2-b:4,5-b&cent, ]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.

An efficient scheme for the synthesis of 1,1-cyclopentylenylbisphenol (bisphenol CP) has been developed starting from dicyclopentadiene, a C5 byproduct from the petroleum cracking process. The synthetic steps leading to bisphenol CP consist of mostly isomerization and addition reactions, which are higher in their atom-economy efficiencies than those based upon condensation reactions. In addition, alkoxylation by cyclic carbonates converted bisphenol CP into ethoxylated and propoxylated ether diols. The transformation of hydroxyl functional groups from bisphenols to alkoxylated alcohols increased the reactivity of their hydroxyl groups toward isocyanates, as evidenced by achieving >3 times higher molecular weights of the segmented polyurethanes (PUs) in GPC analysis using alkoxylated diols as chain extenders instead of bisphenols. In addition, the incorporation of five-membered cardo-type groups onto the PU side chains through alkoxyl diols of bisphenol CP also significantly enhances the phase mixing of th...

To achieve sustainability, many kinds of bio-based epoxy resins have been developed. However, to the best of our knowledge, a 100% bio-based epoxy thermoset has rarely been reported since it needs both the epoxy resin and curing agent to be bio-based. This work provides a facile strategy to achieve epoxy thermosets with 100% bio-based content. The strategy includes the preparation of four bio-based epoxy resins 1–4 and their thermosets through the self-curing reaction of 1–4. The epoxy compounds 1–4 were prepared from the esterification of eugenol with succinyl, adipoyl, suberoyl, and 2,5-furan chloride, respectively, followed by the oxidation of the allylic bond. Through NMR, DSC, and FTIR analyses, we confirm that the self-curing reaction of 1–4 occurred through a 4-dimethylpyridine (DMAP)-catalyzed reaction of active esters and epoxides. This work successfully provides a facile strategy to achieve fully bio-based epoxy thermosets.

In this study, we first revealed green materials – poly-lysines (poly-L-lysine and poly-L-lysine blend poly-D-lysine) – as electron-extraction layers (EELs) in organic photovoltaics (OPVs). The distinct configurations of poly-lysine enantiomers were verified by conducting zeta potential analysis, and their work function (WF)-tuning capabilities for indium tin oxide (ITO) were affirmed by ultraviolet photoelectron spectroscopy (UPS). These two poly-lysine groups, with different arrangements of the amino groups that built up different surface dipoles on the ITO substrate, altered the surface energy and WF of ITO. Poly-L-lysine optimized the WF of ITO for efficient carrier transport in the OPV device, in the electron transporting layer-free OPV devices, and we observed a high power conversion efficiency (PCE) of 10.01% in the device configuration of ITO/interlayer/BHJ/MoO3/Ag. As the first examination of poly-lysine enantiomers for OPVs, we provided the WF-tuning functions – increasing polarity as an interfacial dipole is formed at the corresponding interface, and discovered a promising interfacial material possessing high efficiency and benefitting from a long-term stability to perform in a stable PCE with about 80% of its original PCE remaining after continuous heat and light treatment for 400 hours.

A series of twisted N,N-linked benzo[ghi]-perylenetriimide dimers (t-BPTI) with various lengths of the α-branched alkyl side chain at the six-membered imide ring position was designed, synthesized, and characterized. These compounds showed the low-lying LUMO energy level of -3.78 eV, which was similar to that of PC61 BM (-3.71 eV), but with intensive optical absorption in the range 350-500 nm. The twisted molecular geometry with two nearly perpendicular BPTI planes achieved a favorable nanoscale phase separation by relieving the self-aggregation of rigid BPTI units in blend films. The acceptor t-BPTI-3 unit with the longest alkyl side chains has been demonstrated to be an efficient electron acceptor in solution-processed bulk heterojunction organic photovoltaics (OPV), giving a power conversion efficiency of 3.68 % when using conjugated polymer PTB7-Th as the donor and without additional treatments.

Three dimesitylborane-containing fluorophores with various π-conjugated systems attached at the 9th position of carbazole, namely, 9-(4′-bromobiphenyl-4-yl)-9H-carbazole (Cz9Ph2B), 9-(4-(5-(dimesitylboryl)thiophen-2-yl)phenyl)-9H-carbazole (Cz9ThPhB), and 9-(4-(4-(dimesitylboryl)styryl)phenyl)-9H-carbazole (Cz9SB) were synthesized and their photophysical and electroluminescent properties were investigated for application in nondoped blue OLEDs as well as red phosphorescent OLEDs (PhOLEDs). The electron-accepting dimesitylboryl group and various π-conjugated segments appended to the electron-donating carbazole moiety impart the three fluorophores with bipolar transporting ability, and their energy levels are matched with those of the adjacent carrier-transporting layers. These bulky fluorophores are thermally stable with glass transition temperatures and degradation temperatures reaching up to 105 and 383 °C, respectively. In addition, efficient nondoped Cz9PhThB- and Cz9SB-based blue OLEDs with maximum currents of 1.51 and 4.03 cd A−1 and external quantum efficiencies (EQE) of 2.30 and 4.72% were achieved, respectively. Notably, the Cz9Ph2B-based red PhOLEDs exhibits a relatively low turn-on voltage (3.3 V) and high electroluminescence efficiencies (maximum current = 23.12 cd A−1 and EQE = 14.10%). Their performance is superior to that of the corresponding device using conventional 4,4′-N,N′-dicarbazolbiphenyl as the host material. Moreover, a maximum brightness of 39700 cd m−2 was also achieved.

NORYL™ SA9000 resin is a commercialized telechelic PPO oligomer with phenyl methacrylate end groups. However, neat SA9000 thermoset is brittle after thermally curing. To find a method to enhance the toughness of neat SA9000 thermoset, three model reactions are designed. The first one is the 4-dimethylaminopyridine (DMAP)-catalyzed homopolymerization of glycidyl phenyl ether. The second one is the reaction of glycidyl phenyl ether and phenyl acetate in the presence of DMAP. The third one is the reaction of glycidyl phenyl ether and phenyl methacrylate in the presence DMAP. Through 1H NMR analysis, the product is 1,3-diphenoxy-2-acetoxypropane and 1,3-diphenoxy-2-methacryalatepropane, respectively, for model reactions 2 and 3. According to the structure of products, we identify the reaction mechanisms between the phenyl acetate and epoxy, and between the phenyl methacrylate and epoxy. Based on the knowledge, we used two commercialized epoxy resin (DGEBA and HP7200) to copolymerize with SA9000 in the presence of DMAP and tert-butyl cumyl peroxide (TBCP). The toughness of the thermosets are significantly improved, which means the brittle drawback of neat SA9000 thermoset has been solved. Homogeneous, flexible thermosetting films with high glass transition temperatures, low dielectric constants, and extremely low dissipation factors are obtained.

Through the use of organic/inorganic hybrid dispersants—which are composed of polymeric dispersant and two-dimension nanomaterial graphene oxide (GO)—copper nanoparticles (CuNPs) were found to exhibit nano stability, air-stable characteristics, as well as long-term conductive stability. The polymeric dispersant consists of branched poly(oxyethylene)-segmented esters of trimellitic anhydride adduct (polyethylene glycol−trimethylolpropane−trimellitic anhydride, designated as PTT). PTT acts as a stabilizer for CuNPs, which are synthesized via in situ polymerization and redox reaction of the precursor Cu(CH3COO)2 within an aqueous system, and use graphene oxide to avoid the reduction reaction of CuNPs. The results show that after 30 days of storage the CuNPs/PTT/GO composite film maintains a highly conductive network (9.06 × 10−1 Ω/sq). These results indicate that organic/inorganic PTT/GO hybrid dispersants can effectively maintain the conductivity stability of CuNPs and address the problem of CuNP oxidation. Finally, the new CuNPs/PTT/GO composite film was applied to the electrocardiogram (ECG) smart clothes. This way, a stable and antioxidant-sensing electrode can be produced, which is expected to serve as a long-term ECG monitoring device.

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.

In this study, we synthesized two emeraldicene (EMD)-based conjugated polymers, PBTEMD and PFEMD, through polymerization of 4,7-di(thien-2-yl)benzo[ c ][1,2,5]thiadiazole and 9,9-bis(2-ethylhexyl)-9H-fluorene, respectively. We then blended these EMD-derived polymers (as electron-donating materials) with [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) in the active layers of polymer solar cells (PSCs) and investigate their optoelectronic properties and related photovoltaic performance. To best of our knowledge, this study is the first to use EMD derivatives for PSC applications. We compared the molecular structures, absorption behavior, energy levels, thermal properties, and thermal stability of these two polymers to determine their suitability for use in PSCs. The main absorption of PFEMD was in the near-IR spectrum (600–800 nm). We observed a transparency of greater than 80% for the blend film of PFEMD having a thickness of 95 nm; the constructed device exhibited a power conversion efficiency (PCE) of 2.5% and the transparent PFEMD:PC 61 BM-derived device exhibited a PCE of 1.2% under AM 1.5 G irradiation (100 mW cm −2 ). We observed a significant improvement in thermal stability for the device incorporating the additive crosslinker TBT-N 3 ; it retained approximately 60% of its initial PCE after accelerated heating (150 °C) for 18 h. In contrast, the PCE of the corresponding normal device decayed to 0.01% of its initial value.

Polyurethanes grafted with well-defined polar pendants were synthesized and investigated. A series of linear and dendritic poly(urea/malonamide)s with uniform chain length were first prepared from an iterative synthesis route, which is based on a dual-functional building block, 4-isocyanate-4´-(3,3-dimethyl-2,4-dioxo-azetidine)diphenyl methane (IDD). Moreover, side chain polyurethanes (SPUs) bearing azetidine-2,4-dione functional groups were prepared from one pot reaction for following post-functionalization of poly(urea/malonamide)s when IDD-diols were added to polyurethane prepolymers as chain extenders. Subsequently, the azetidine-2,4-dione functional groups on the SPUs underwent addition reactions with amino functional group containing dendritic or linear poly(urea/malonamide)s under mild condition, without the need of catalyst and protection/deprotection procedure to achieve polyurethanes grafted with well-defined pendants. Mechanical properties of these comb-like polyurethanes strongly depend on the architecture and the molecular length of poly(urea/malonamide) pendants, which could be adjusted by the grafting fractions of the dendritic or linear poly(urea/malonamide)s with various generations. These poly(urea/malonamide) pendants provided strong hydrogen bonding interactions to achieve physical crosslinking effects in the polyurethanes. Consequently, the polyurethanes with improved mechanical properties and sustained phase transition exhibit shape memory properties.

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&rsquo, ((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&rsquo, (4,4&rsquo, (propane-2,2-diyl)bis(4,1-phenylene))bis(oxy)dianiline (BPAA), and 4,4&prime, (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 this study, spirobisindane-functionalized graphene oxide (SFGO)/polyimide (Matrimid® 5218, i.e. M) solutions are spin-coated onto a polysulfone support to produce SFGO@M nanocomposite membranes for alcohol dehydration by pervaporation. Compounds 3,3,3′,3′-tetramethyl-1,1′-spirobisindane-6,6′-diol (TSD) and 4,4′-((3,3,3′,3′-tetramethyl-2,2′,3,3′-tetrahydro-1,1′-spirobi[indene]-6,6′-diyl)bis(oxy))dianiline (TTSD) are synthesized based on a conversion reaction from bisphenol A (BPA). Both TSD and TTSD contain spirobisindane structure, which is inspired by the structural unit from polymers of intrinsic microporosity. The fine structural characteristics of SFGO@M membranes are evaluated using positron annihilation lifetime spectroscopy. The membrane free volume increases in the following order: M

A spirobichroman dianhydride (SBCDA) was prepared through oxidation of an octamethyl spirobichroman (OMSBC), which was synthesized from acid-fragmentation of bisphenol A by 3,4-dimethylphenol, followed by Diels–Alder reaction. The reaction mechanism was proposed, and the optimal reaction conditions were discussed. Based on a high temperature solution polymerization of SBCDA and 4,4′-diaminodiphenylmethane (DDM), a spirobichroman-containing polyimide, SBC-DDM, was successfully prepared. Because of the contorted spiro-structure and rigid polymer backbone, SBC-DDM exhibits a large free volume, leading to outstanding organo-solubility and a low dielectric constant. In addition, the resulting film of SBC-DDM shows foldability, a high glass transition temperature, and good thermal stability.

Polythiophenes (PTs) featuring di(ethylene glycol)-substituted 2,5-thienyl diketopyrrolopyrrole (DG-TDPP) moieties as conjugated units in the polymer backbone and tert-butyl-substituted triphenylamine (tTPA)-containing moieties as pendant units have been synthesized through Stille coupling. Incorporating the electron-deficient DG-TDPP moieties within the polymer backbone and appending the tTPA units promoted charge balance and efficient conjugation within the extended conjugated frameworks of the polymers, resulting in lower band gap energies and red-shifting the maximum UV-Vis absorption wavelength. The influence of the DG-TDPP content on the optical, electrochemical, and photovoltaic (PV) properties of the polymers has been studied. Incorporating a suitable content of DG-TDPP moieties in the polymer backbone enhanced the solar absorption ability and conjugation length of the PTs. The PV properties of bulk-heterojunction solar cells based on PT/fullerene derivatives improved after incorporating DG-TDPP units in the backbones of the side chain-conjugated PTs.

In this work, we prepared four star-shaped conjugated small molecules, the triphenylamine dithiophene (TBT) derivatives, namely TBT-H, TBT-Br, TBT-OH, and TBT-N 3 presenting hydride, bromide, hydroxyl, and azide terminal functional groups, respectively. These TBT derivatives were used as additives in the active layers of organic photovoltaics to investigate the effect of intermolecular interactions (TBT-H, TBT-OH) or crosslinking (TBT-N 3 , TBT-Br) on the long-term thermal stability of the devices. From analyses of blend film morphologies, and optoelectronic and device performance, we observed significant enhancements in thermal stability during accelerated heating tests at 150 °C for the devices incorporated with the additives TBT-N 3 and TBT-Br. These two additives functioned as crosslinkers, and constructed local borders that effectively impeded heat-promoted fullerene aggregation, thereby leading to highly stable morphologies. When compared with corresponding normal devices, the TBT-N 3 –derived devices based on poly(3-hexylthiophene) exhibited greater stability, with the power conversion efficiency (PCE) remaining as high as 2.5% after 144h at 150 °C. Because of this enhancement, a device based on an amorphous low-bandgap polymer, namely poly(thieno[3,4- b ]thiophene- alt -benzodithiophene), with the addition of TBT-N 3 was fabricated. We observed a significant improvement in device stability, retaining approximately 60% (from 5.0 to 3.3%) of its initial PCE under accelerated heating (150 °C). In contrast, the PCE of the corresponding normal device decayed to 0.01% of its initial value.

A series of urea/malonamide dendritic molecules were prepared as gate insulators for organic thin film transistors (OTFTs). This series of molecules with different degrees of branching possess peripheral stearyl groups are dendrons generation 0.5 (G0.5), generation 1 (G1), generation 1.5 (G1.5), generation 2 (G2) and generation 2.5 (G2.5). In addition, two types of tetracarboxylic diimide derivatives, i.e. perylene diimide (PDI) and naphthalene diimide (NDI) with two different chain lengths of fluorinated alkyl end groups were prepared as semiconductors for OTFTs such as NDI-C4F7, NDI-C7F9, PDI-C4F7 and PDI-C7F9. The n-channel types of OTFTs were fabricated by spin-coating the gate insulators on Si/SiO2 substrates, and then depositing the semiconducting layers in vacuum without heating the substrate. Silver was used as contact electrodes for source and drain. The performance of OTFTs with dendrons as gate insulators were better than that of OTFTs modified by octadecyltrichlorosilane (ODTS). Moreover, the threshold voltages (Vths) of OTFTs shifted from positive voltage to negative voltage as the device was incorporated with higher generation of dendrons. This is because of different dielectric constants or surface energies between the interface of gate insulator and semiconducting layer. Among all samples in this study, the n-channel OTFT comprising PDI-C4F7 and G1.5 exhibited the best performance. In addition, an enhanced electron mobility and Ion/Ioff ratio measured under ambient condition were 4.71 × 10− 4 cm2 V− 1 s− 1 and 7.7 × 103, respectively. Apart from that, the influence of semiconducting molecular packing order on dendron gate insulator layers was investigated by grazing-incidence wide-angle X-ray scattering (GIWAXS) and atomic force microscopy (AFM). Furthermore, pentacene-based p-channel OTFTs with G1.5 gate insulator also exhibited the highest performance. These OTFTs achieved 0.1 cm2 V− 1 s− 1 and 6.3 × 104 for mobility (μ) and Ion/Ioff ratio, respectively.

Polymer properties along with recycling processes remain a constant challenge for post-recycled polymers. In this study, the development of recycling feasibility, monomers reactivity, and the chemical-recycled polymer properties from polycarbonate (PC) waste were demonstrated. Through selective aminolysis under mild conditions, the reduced molecular-weight products (or monomer mixtures) with newly incorporated flexible-ether linkages as building blocks were realized. By using the commodity monomers such as isocyanate reagents, monomer mixtures were readily to be re-connected into polyurethanes in one-pot process without prior purification of the recycled monomer mixtures. Due to the presence of urethane groups, the enhanced reactivity of the terminal phenolic hydroxyl groups of the monomer mixtures toward isocyanate groups would afford high molecular weights over ~80,000 g/mol for thermoplastic polyurethanes (TPUs). Moreover, by taking advantage of low melting point polyether-type polyols along with optimizing processing conditions, the TPUs exhibited a unique phase separation morphology with domain sizes ranging from ~10 nm to ~25 nm as investigated by using small angle X-ray scattering (SAXS) measurements. This work demonstrate that the PC waste was fully transformed into TPUs which exhibited improved elastomeric properties.

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 (ηext) 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.

To study the co-reaction of benzoxazine and triazine, a triazine-containing benzoxazine (P-tta) was prepared through nucleophilic substitution of 4-(2H-benzo[e][1,3]oxazin-3(4H)-yl)phenol (P-ap) with 2,4,6-trichloro-1,3,5-triazine. DSC thermograms show that the exothermic temperature of P-tta is lower than that of other benzoxazines with a similar structure except for the triazine structure, so we speculate that the forward polymerization is related to the existence of the triazine structure. Through monitoring the curing process using IR, we propose that the curing reactions of P-tta include a concerted co-reaction between the triazine and benzoxazine, and a self-polymerization of benzoxazine. A thermoset with a high Tg (279 °C, DMA data), a low thermal expansion coefficient (32 ppm per °C), and high thermal stability (Td5% 417 °C) can be obtained through the curing of P-tta.