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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.

In this study, a series of crosslinked membranes were prepared as solid polymer electrolytes (SPEs) for all-solid-state lithium ion batteries (ASSLIBs). An epoxy-containing copolymer (glycidyl methacrylate-co-poly(ethylene glycol) methyl ether methacrylate, PGA) and two amine curing agents, linear Jeffamine ED2003 and hyperbranched polyethyleneimine (PEI), were utilized to prepare SPEs with various crosslinking degrees. The PGA/polyethylene oxide (PEO) blends were cured by ED2003 and PEI to obtain slightly and heavily crosslinked structures, respectively. For further optimizing the interfacial and the electrochemical properties, an interlocking bilayer membrane based on overlapping and subsequent curing of PGA/PEO/ED2003 and PEO/PEI layers was developed. The presence of this amino/epoxy network can inhibit PEO crystallinity and maintain the dimensional stability of membranes. For the slightly crosslinked PGA/PEO/ED2003 membrane, an ionic conductivity of 5.61 × 10−4 S cm−1 and a lithium ion transference number (tLi+) of 0.43 were obtained, along with a specific capacity of 156 mAh g−1 (0.05 C) acquired from an assembled half-cell battery. However, the capacity retention retained only 54% after 100 cycles (0.2 C, 80 °C), possibly because the PEO-based electrolyte was inclined to recrystallize after long term thermal treatment. On the other hand, the highly crosslinked PGA/PEO/PEI membrane exhibited a similar ionic conductivity of 3.44 × 10−4 S cm−1 and a tLi+ of 0.52. Yet, poor interfacial adhesion between the membrane and the cathode brought about a low specific capacity of 48 mAh g−1. For the reinforced interlocking bilayer membrane, an ionic conductivity of 3.24 × 10−4 S cm−1 and a tLi+ of 0.42 could be achieved. Moreover, the capacity retention reached as high as 80% after 100 cycles (0.2 C, 80 °C). This is because the presence of the epoxy-based interlocking bilayer structure can block the pathway of lithium dendrite puncture effectively. We demonstrate that the unique interlocking bilayer structure is capable of offering a new approach to fabricate a robust SPE for ASSLIBs.

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.

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.

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.

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.

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.

Raman enhancement on nonmetallic flat two-dimensional (2D) nanomaterial surfaces has attracted a great deal of attention since the discovery of graphene-enhanced Raman scattering. Molybdenum disulfide (MoS2) is a flat 2D nanomaterial with unique electronic and physical properties that can be applied in surface-enhanced Raman spectroscopy (SERS). Herein, we report a lithium-exfoliated MoS2 (Li-MoS2) has a metallic phase content of about 70%, which is three times higher than the metallic phase content of 20% in thioglycolic acid-exfoliated MoS2 (T-MoS2). Li-MoS2 therefore displays a 2–3 fold increase in the Raman signal for rhodamine 6G (R6G) used as an analyte. Furthermore, the conjugation of a thiol-terminated alkyne with Li-MoS2 also provided a greater SERS signal at 2123 cm−1 than that of T-MoS2. A defect-rich metallic MoS2 monolayer can therefore be used as the perfect substrate for surface-enhanced Raman scattering, although pristine MoS2 hardly exhibits an SERS effect. This study proved that (1) defect-rich metallic MoS2, (2) dipole–dipole interactions, and (3) the enhanced charge transfer effect of MoS2 monolayers are the three primary and essential parameters for enhancing the Raman signals of analytes on MoS2. Key observations include the fact that some alkyne groups were directly coordinated to the edges of Li-MoS2 defect sites, which shifted the alkyne signal to 2153 cm−1 in alkyne spectral mapping. More importantly, to quantify the SERS performance of Li-MoS2, SERS imaging of live cells was demonstrated using the unique alkyne signal at 2123 cm−1.

In this study, we examined the effects of using the p-type conjugated polymers J51 and FATZ as the third component in PM6:Y6–based donor:donor:acceptor (D:D:A) ternary organic photovoltaics (OPVs). We used UV–Vis spectroscopy, photoluminescence spectroscopy, atomic force microscopy, and grazing-incidence wide-angle X-ray scattering to investigate the optoelectronic and morphological properties of the resulting ternary blend films. We evaluated the carrier transport properties of these OPVs to identify the mechanism governing their power conversion efficiencies (PCEs). Of our two tested polymers, FTAZ had more suitable energy levels and miscibility; therefore, its presence increased the open-circuit voltage of the resulting ternary device. The embedded FTAZ facilitated the molecular packing of Y6 and improved the charge transport in the ternary blend, thereby improving the PCE of the device from 14.3% (binary) to 15.3% (ternary).

A novel N-methylphenothiazine based ionic liquid (NMP-IL) was designed for achieving low-driving voltage electrochromic device (ECD) with thermal durability. NMP-IL was synthesized via a five-step reaction, including thionation, methylation, substitution, ionization, and anion exchange. By chemically bonding with the ionic liquid, NMP-IL exhibited a large optical contrast and high thermal stability simply to take the advantages of both NMP and ionic liquid features. Compared to NMP, NMP-IL would provide the electrolyte with a higher ionic conductivity, thus reducing the driving voltage of the ECDs. Most importantly, an extremely low-driving voltage (0.6 V) ECD based on NMP-IL and nickel hexacyanoferrate (NiHCF) thin film, known as the ion storage layer, was further demonstrated. The proposed NMP-IL/NiHCF ECD accomplished a large transmittance change of 56.6% at 575 nm, a desirable coloration efficiency of 166 cm2/C, and attenuated 120.9 W/m2 solar irradiance between bleached state and colored state with a minimal consumed power per unit area of 1.08 W/m2. Besides, impressive long-term stabilities of the proposed ECDs, under both room temperature (92.3% retention of its original ΔT after 10,000 cycles) and high temperature (80.2% retention of its original ΔT after 3,000 cycles at 65 °C), were achieved. These merits reveal that NMP-IL has the potential to become the new anodically coloring material for application in energy-saving ECDs.

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.

This study investigated films with remarkably high electrical conductivity after they were easily prepared from organic/inorganic nanohybrid solutions containing an organic polymeric dispersant and two-dimensional nanoscale silicate platelets as the inorganic stabilizer dispersed with silver nanoparticles. Transmission electron microscopy shows that the production of silver nanoparticles synthesized by the in situ chemical reduction of AgNO3 in an aqueous solution by N,N-dimethylformamide results in an average silver nanoparticle diameter of circa 20 nm. Thin films of silver nanoparticles were prepared on a 1-&mu, m-thick film with a low sheet resistance of 8.24 &times, 10&minus, 4 &Omega, /sq, achieved through the surface migration of silver nanoparticles and prepared by sintering at 300 &deg, C to form an interconnected network. This was achieved with a silver nanoparticle content of 5 wt%, using nanoscale silicate platelets/polyoxyethylene-segmented polyimide/AgNO3 at a weight ratio of 1:10:35. During sintering, the color of the hybrid film changed from gold to milky white, suggesting the migration of silver nanoparticles and the formation of an interconnected network. The results show promise for the fabrication of novel silver-based electrocardiogram electrodes and a flexible wireless electrocardiogram measurement system for wearable electronics.

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

Series of dendritic building blocks (G series) with various periphery alkyl chain lengths (C3, C10 and C18) were prepared via convergent synthesis route through reaction-selective building block, (4-Isocyanato-4′(3,3-dimethyl-2,4-dioxo-azetidino)diphenylmethane, IDD) and diethylenetriamine (DETA) via alternative addition and ring-opening reaction. These azetidine-2,4-dione containing dendritic building blocks then reacted with several amino acid compounds to generate the corresponding dendritic co-adsorbents (GA series). GA series comprising different generations, various alkyl chain lengths closed to anchor and/or in the periphery are discussed and applied into dye-sensitized solar cells (DSSCs). The cells utilized similar phenothiazine-based dyes (HL5) as sensitizer with fixed concentration (0.3 mM) of co-adsorbents are fabricated to explore the effect on cell performances and interfacial charge properties. Power conversion efficiencies (PCEs) of 7.02–7.76% were achieved, which better than the commercially available CDCA co-adsorbent based cell (6.71% ± 0.14%). In addition, the highest conversion efficiency also reaches 95% of the standard cell based on N719 metal dye. Herein, several observations: (1) under various alkyl chain lengths closed to anchor, the longest one has efficient charge recombination; (2) under various alkyl chain lengths in the periphery, the moderate one has the best interfacial properties with the longest electron lifetime value; (3) under different generations, the largest one can reduce dye aggregation and charge recombination significantly. Based on our pervious initial study on dendritic co-adsorbents, we further investigated several molecular design on dendritic co-adsorbents to realize the structural effect on cell performance that might be useful for DSSC applications.

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.

Over the years, the manipulation of polymer microphase separation associated with molecular architectures has been holding great promise for rendering structure-property relationship. A series of poly (urea/malonamide) dendrons bearing rigid adamantanes in the periphery were developed to serve as branching hard segments (HS) for thermoplastic polyurethanes (TPUs) either in end-capping or pendant manner. Thermal properties, crystalline structures, and mechanical properties of the TPUs were investigated by DSC, X-ray scattering, and DMA, respectively. The introduction of the branching units with bulky adamantanes would expectedly hinder the crystallization of HS. Intriguingly, the dendrons not only accelerate the crystallization of the soft segment (SS, based on polycaprolactone polyol (PCL)), but promote the phase separation between HS and SS to form distinct microdomains as well. These enhanced effects revealed a size-dependent relationship with growing size (or generation) of the branching HS. With the high SS crystallinity that can freeze the chain mobility and the robust HS domains that work as the physical crosslinking points, the resulting TPUs incorporated with adamantane-bearing units show superior shape memory behaviors. This work demonstrates that the molecular engineering on the architectures can significantly tailor the microstructures and properties of thermal plastic polymers.

In this study, we first revealed a green material-Poly-lysine as an interfacial layer (IFL) of electron-extraction layer (EEL) and investigated evolution of morphologies of the active layers in organic photovoltaics (OPVs). The surface structure of the active layers was characterized by atomic force microscopy (AFM) and the molecular packing features were revealed by grazing-incidence wide-angle X-ray scattering (GIWAXS). By embedding poly-lysine as IFL, we evidenced the changes of the blend film phase segregation and observed an increase order of molecular packing in preferential face-on orientation. The optimized blend film morphology facilitated the carrier extraction, thereby significantly improved the OPV performance with the best power conversion efficiency (PCE) of 12.5% and 15.3% for the PBDB-T-2Cl:IT-4F and PBDB-T-2F:Y6 blends, respectively. Compared with the controlled devices, the poly-lysine-modified devices showed significantly improved thermal-and photo-stability which keeps 80% of its initial efficiency after 400-h heating and illumination. As the first discovery of its general applicability of the promising IFL material, poly-lysine was further applied to fabricate a flexible OPV device using 100% bio-based polyethylene furandicarboxylate (PEF) substrate and its derived OPV device exhibited a PCE greater than 7% and maintained the 80% efficiency under the high bending radius of 3 mm. The present study suggests the potential application of using bio-based materials for flexible OPV applications.

In this study we used p-type [poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) and nickel oxide] and n-type (sol–gel and nanoparticle zinc oxides) materials as transporting layers for PM6:Y6–based organic photovoltaic (OPV) devices. These solution-processed transporting layers exhibited various surface energies, morphologies, and roughnesses that affected the subsequent growth of PM6:Y6 blend films. Using atomic force microscopy and grazing-incidence wide-angle X-ray spectroscopy, we observed various PM6:Y6 blend film morphologies on the different substrates. Furthermore, the surface-induced PM6:Y6 blend morphology influenced the mechanism of carrier recombination and, thereby, affected the device performance. Among our tested systems, the PEDOT:PSS–based devices exhibited superior surface properties, possessed larger phase-segregated domains, and featured strong molecular packing, all of which resulted in OPVs displaying power conversion efficiencies (PCEs) of up to 11.5%. When incorporating 1-chloronaphthalene as an additive during solution processing, the molecular packing was enhanced, thereby improving the PCE of the resulting devices from 11.5 to 13.4%. Devices incorporating ZnO (sol–gel) displayed performance comparable with that of the PEDOT:PSS–based devices, but exhibited superior air stability without encapsulation (25 °C, 40% humidity).

Among many cathode materials, nickel-rich LiNi0.8Co0.1Mn0.1O2 (NCM 811) has been spotlighted as one of the most feasible candidates for next-generation LIBs because of its high discharge capacity (~200 mAh/g). However, NCM 811 shows significant performance degradation, which is mostly attributed to cation mixing, surface side reactions, and intrinsic structural instability originating from the large volume changes during repeated cycling. Conventional lithium ion batteries (LIB) normally use flammable nonaqueous liquid electrolytes, resulting in a serious safety issue in use. In this respect, all solid state lithium ion batteries (SSLIBs) are regarded as a fundamental solution to address the safety issue by using a solid state electrolyte (SSE) in place of the conventional liquid one. This study assess the performance of NCM811 cathode for all-solid-state batteries based on hybrid PEO-ceramic solid electrolyte. Artificial CEI coating layer has been developed in order to prevent direct contact of electrolyte with the cathode, thus avoid the negative effects, such as side reactions, on NCM 811. The incorporation of ceramic materials results composite electrolytes, containing inert fillers, offer improved mechanical stability under high operating temperature. It is demonstrated that the polymer of hybrid electrolytes can penetrate into cathode, providing a good Li+ transfer channel inside the battery under high operating temperature. Moreover, the protective coating on NCM811 effectively improve the electrochemical stability. (This work is supported by Ministry of Science and Technology, Taiwan under contract number: MOST 108-3116-F002-008)

The recent use of non-fullerene materials has significantly increased the efficiency of organic photovoltaic (OPV), with ternary OPVs providing an effective means of further enhancing the performance. In this study, we evaluated the role played by the small molecule Y6 as the third component in additive-free PM6 (polymer): Y6:IT-4F (small molecule) ternary OPVs. We used UV–Vis spectroscopy, photoluminescence spectroscopy, and tapping-mode atomic force microscopy to study the effects of various blend ratios on the optoelectronic properties of these OPVs. At the optimized PM6:Y6:IT-4F blend ratio (1:0.35:0.75), we observed the presence of Y6:IT-4F intermediates that efficiently suppressed the over-segregation of Y6 and increased the degree of carrier transport. The optimized ternary OPV delivered an average power conversion efficiency (PCE) of 13.6 ± 0.29% and the best PCE of 14.14%, which was 23% enhancement compared with the binary OPV. The findings suggest that dual effects, caused by the use of solvent and optimization of the blending ratio of primary and secondary acceptors, significantly influence the performance of OPVs.

We designed and synthesized a novel series of two-dimensional (2D) conjugated polymers (P1-2T, P2-2T2F and P3-4T2F) containing 2,2′-bithiophene (2T) and 3,3′-difluoro-2,2′-bithiophene (2T2F) as donor units, and 4,7-benzo[c][1,2,5]thiadiazole (BT) and 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (DTBT) as acceptor units appended with conjugated vinyl-terthiophene (VTT) side chain. We comprehensively investigated the effect of fluorination and thiophene (T) π-spacer on the optoelectronic properties and photovoltaic performance of the resulting copolymers. In comparison with non-fluorinated polymer P1-2T, the fluorinated polymer P2-2T2F and P3-4T2F had down shifted highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels with an enhanced absorption band. Moreover, 2D grazing incidence wide-angle X-ray scattering and space charge limited current measurement showed that the presence of thiophene π-spacer in P3-4T2F promoted dominant face-on orientation, high crystallinity and enhanced hole mobility, compared with P2-2T2F. As a result, the inverted polymer solar cell based on the P3-4T2F:PC61BM blend exhibited a high power conversion efficiency (PCE) of 6.66% with a Jsc of 12.99 ± 0.30 mA/cm−2. In contrast, the P1-2T:PC61BM and P2-2T2F:PC61BM devices without π-spacer showed a PCE of 2.22% and 0.95%, respectively. The PCE of the P3-4T2F:PC61BM device was further improved to 6.89% by using a polyethylenimine ethoxylated (PEIE) interlayer between ITO and ZnO. This study reinvigorates the key modulation of a 2D conjugated polymer with improved photovoltaic performance.

Water-dispersible polymers represent an evolved category in the chemical industry in terms of an eco-friendly technology to meet the desired performance and to reduce the use of volatile solvents. One of the major challenges in the development of water dispersible resins deeply relies on the emulsification process that often requires the ionization process or the use of additional surfactants. In this study, an efficient method for the preparation of amphiphilic comb-like poly(hydroxyaminoethers), which consists of hydrophobic epoxy resins as the backbone and hydrophilic polyethers as the side chains, were realized in the absence of catalysts or initiators. Different from the conventional epoxy resin dispersions prepared in the presence of surfactants, or through ionization process, these amphiphilic comb-like polymers exhibited self-dispersed properties to achieve stable non-ionic emulsions in the water. The hydrophilic contents of these comb-like poly(hydroxyaminoethers) could be easily tailored in a wide range from less than 20 wt% to over 65 wt%, along with glass transition temperatures ranged from −45 °C to ~ 50 °C. In addition, the emulsifying ability was facilitated via the variations of the polymer architectures and compositions. Anti-corrosion properties were also evaluated for these self-dispersible poly(hydroxyaminoether) emulsions.

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)/NiOx/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.

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 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+. Synthesis of poly(NIPAAm-co-NMA-co-RhBN2AM) with different compositions were 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 nonfluorescent to red fluorescence while sensing pH or Hg2+, and high reversibility of on/off switchable fluorescence emission 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 multifunctional sensory devise for specific heavy transition metal (HTM) in aqueous solutions.

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.

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. With the addition of a small amount of dendritic surfactants to polymers such as poly(D,L-lactide), polystyrene or poly(methyl methacrylate), a well-organized honeycomb-like surface could be achieved. These uniform porous arrays from the BF method with free-standing capacity benefit from the support of their polymer matrices without resorting to a painstaking polymerization process to provide bulky dendritic side-chain polymers. The formation of water-driven honeycomb-like surfaces was also dependent on the concentration of surfactants in a polymer matrix, apart from the chemical structure. Furthermore, a quantitative analysis of the interfacial tensions between water and polymer solution revealed a dynamic procedure of water droplets stabilized by the surfactants on the as-cast polymer films during the solvent evaporation step of the BF method. Among all these dendritic surfactants, the dendrons with one or two hydroxyl groups at the focal point and plenty of octadecyl groups in the periphery exhibited an amphiphilic nature, and were able to create well-balanced interfacial tensions capable of maintaining water in droplets. Consequently, this type of dendron as a surfactant can be blended with a wide range of polymers to create regular honeycomb-like arrays.

In this study, we systematically investigated the plasmonic effects of silver nanoplates (Ag NPLs) embedded in organic and perovskite (PVSK) photovoltaic (PV) cells. Optical properties of the Ag NPLs were manipulated by varying their sizes and shapes through controllable wet chemical processes. As the lengths of the edges of the Ag NPLs increased, their surface plasmon resonance bands broadened, with the maximum extinction wavelength extending to as far as 750 nm. After embedding various types of Ag NPLs into the PEDOT:PSS [poly(3,4-ethylenedioxythiophene)/polystyrenesulfonate] layer, the short-circuit photocurrent density increased by 7.6–17.5%, relative to that of the pre-optimized control PVs, with the power conversion efficiency (PCE) increasing by up to 13%. We obtained an optimized PCE of 8.5% for normal PVSK device under simulated AM 1.5G irradiation (100 mW cm−2). After the incorporation of Ag NPLs, a much higher PCE of 9.6% was obtained. External quantum efficiencies were increased significantly as a result of the increased plasmonic scattering effect of Ag NPLs.

In this study we prepared three star-shaped, triphenylamine-cored conjugated molecules, possessing thienylenevinylene units as conjugated π bridges and thienyl, 2-ethylhexyl cyanoacetate, and 1,3-diethyl-2-thiobarbituric acid moieties, respectively, as peripheral groups—for use as donor materials in small molecule/fullerene bulk heterojunction-type organic photovoltaic cells (OPVs). The peripheral groups affected the UV–Vis absorption behavior and electrochemical properties of star-shaped molecules, and photovoltaic performance of the star-shaped molecules based OPVs. The wavelength of maximum absorption for star-shaped molecule with 1,3-diethyl-2-thiobarbituric acid moiety was red-shifted relative to those of molecules with thienyl and 2-ethylhexyl cyanoacetate groups, while molecule with thienyl moiety exhibited the largest hole mobility. The photovoltaic properties of cells incorporating molecule with thienyl group and a fullerene derivative were better than those containing corresponding molecule with 2-ethylhexyl cyanoacetate/fullerene or molecule with 1,3-diethyl-2-thiobarbituric acid/fullerene blends. An OPV featuring molecule with thienyl group/fullerene derivative (1:3, w/w) as the active layer exhibited a power conversion efficiency of 1.43%, a short-circuit current density of 5.23 mA/cm 2 , an open-circuit voltage of 0.73 V, and a fill factor of 0.37.

A series of novel triazine-cored, star-shaped, conjugated molecules have been synthesized as donor materials for small molecule based organic solar cells. The structural features of these star-shaped molecules include a planarized triazine as the central core, 2,5-thienyl diketopyrrolopyrrole and 1,4-phenylene diketopyrrolopyrrole as the π-conjugated bridge, and tert -butyl-substituted triphenylamine and tert -butyl-substituted carbazole as the role of end groups and donor units. Photovoltaic properties of the solar cells based on the star-shaped molecule with 2,5-thienyl diketopyrrolopyrrole branches were much better than those of the solar cells based on the one with 1,4-phenylene diketopyrrolopyrrole branches. A power conversion efficiency of 1.57%, a short-circuit current density of 6.34 mA/cm 2 , an open-circuit voltage of 0.73 V, and a fill factor of 0.34 were observed for the organic solar cell based on the star-shaped molecule with 2,5-thienyl diketopyrrolopyrrole branches.