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In all-polymer solar cells (APSCs), number-average molecular weights (Mns) of polymer donors and polymer acceptors play an important role in active layer morphology and photovoltaic performance. In this work, based on a series of APSCs with power conversion efficiency of approaching 10%, we study the effect of Mns of both polymer donor and polymer acceptor on active layer morphology and photovoltaic performance of APSCs. We select poly[4-(5-(4,8-bis(5-((2-butyloctyl)thio)thiophen-2-yl)-6-methylbenzo[1,2-b:4,5-b']dithiophen-2-yl)thiophen-2-yl)-5,6-difluoro-2-(2-hexyldecyl)-7-(5-methylthiophen-2-yl)-2H-benzo[d][1,2,3]triazole] (CD1) as the polymer donor and poly[4-(5-(5,10-bis(2-dodecylhexadecyl)-4,4,9,9-tetrafluuoro-7-methyl-4,5,9,10-tetrahydro3a,5,8,10-tetraaza-4,9-diborapyren-2-yl)thiophen-2-yl)-7-(5-methylthiophen-2-yl)benzo[c][1,2,5]thiadiazole] (PBN-14) as the polymer acceptor. The Mns of polymer donor CD1 are 14.0, 35.5 and 56.1 kg/mol, respectively, and the Mns of polymer acceptor PBN-14 are 32.7, 72.4 and 103.4 kg/mol, respectively. To get the desired biscontinueous fibrous network morphololgy of the polymer donor/polymer acceptor blends, at least one polymer should have high or medium Mn. Moreover, when the Mn of polymer acceptor is high, the active layer morphology and APSC device performance are insensitive to the Mn of polymer donor. The optimal APSC device performance is obtained when the Mn of both the polymer donor and the polymer acceptor are medium. These results provide a comprehensive and deep understanding on the interplay and the effect of Mn of polymer donors and polymer acceptors in high-performance APSCs.

In crystalline/crystalline polymer blend systems, complex competition and coupling of crystallization and morphology usually happen due to the different crystal nucleation and growth processes of polymers, making the morphology and crystallization behavior difficult to control. Herein, we probe the crystallization sequence during the film formation process (crystallize simultaneously, component A crystallizes prior to B or inverse) to illustrate the micro-morphology evolution process in poly(3-hexylthiophene) (P3HT) and poly[[N,N-bis(2-octyldodecyl)-napthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]- alt-5, 5'-(2,2'-bithiophene)] (N2200) blend using in situ UV-vis absorption spectra and in situ two-dimensional grazing incidence X-ray diffraction (2D GIXRD). When P3HT and N2200 crystallize simultaneously, a large-sized morphology structure is formed. When strengthening the solution aggregation of P3HT by increasing the solvent-polymer interaction, P3HT crystallizes prior to N2200. A P3HT-based micro-morphology structure is obtained. As the molecular weight of N2200 increases to a critical value (72.0 kDa), the crystallization of N2200 dominates the film formation process. A N2200-based micro-morphology is formed guided by N2200 domains. The results confirm that the crystallization sequence is one of the most important factors to determine the micro-morphology structure in all-crystalline polymer blends.

The active layer morphology with a domain size of 10–20 nm and large interfacial area plays a significant role in governing the device power conversion efficiency (PCE) of semitransparent polymer solar cells (ST-PSCs). However, the unbalanced aggregation rate of a polymer donor and a near infrared non-fullerene acceptor led to a large phase separation domain. In order to inhibit the intense aggregation of a non-fullerene acceptor, a third component which increases the nucleation and growth barrier of the non-fullerene acceptor can be added to balance aggregation leading to a suitable domain size of donors and acceptors. In order to verify our idea, PTB7-Th and non-fullerene acceptor IEICO-4F were selected as a model system. IEICO-4F tends to form strong aggregation due to its planar conformation. In order to suppress the intense aggregation, an amorphous molecule NCBDT-4Cl which has good miscibility with IEICO-4F is added to increase the nucleation barrier of IEICO-4F because NCBDT-4Cl can be dispersed evenly in the IEICO-4F phase. In situ UV-vis absorption spectra were recorded to monitor the nucleation and growth process of IEICO-4F during the drying process. The results show that the growth time of IEICO-4F is reduced to 45 s from 122 s by incorporating 20 wt% NCBDT-4Cl, resulting in reduced aggregation of IEICO-4F. The small IEICO-4F aggregates disperse in the PTB7-Th matrix and form refined bicontinuous pathways. The optimized ternary ST-PSCs achieve a PCE of 10.31% with an average visible transmittance (AVT) of 20.6%.

The development of all polymer solar cells (all-PSCs) is limited by the lack of polymer acceptors. An effective strategy to design high-efficiency polymer acceptors is to copolymerize small molecular acceptors with electron-rich linking units. In this work, we develop a new polymer acceptor by copolymerizing a small molecular acceptor with an electron-deficient linking unit based on the boron–nitrogen coordination bond (B←N). The incorporation of B←N into the polymer acceptor downshifts the LUMO/HOMO energy levels of the polymer by ca. 0.1 eV, and thus facilitates photo-induced hole transfer from the polymer acceptor to polymer donor. The all-PSC device based on the polymer acceptor containing B←N exhibits a power conversion efficiency (PCE) of 14.3%, which is much higher than that of the control polymer acceptor without B←N (PCE = 7.2%). This is attributed to the improved phase separation morphology and the facilitated photo-induced hole transfer of the active layer based on the polymer acceptor containing B←N. These results suggest that B←N based building blocks with electron-deficient properties are promising to design high-performance polymer acceptors.

A high performance near-infrared organic phototransistor is achieved via introducing a small molecule acceptor as an electron trapping site into the narrow-bandgap conjugated polymer films. With only 10% (wt) addition of the acceptor molecule, the photoresponse to light of 850 nm has been significantly improved with a best photoresponsivity up to 2000 A W-1, high detectivity of 1016 Jones and fairly good photosensitivity in the order of 106.

CCAL1, a member of the tumor necrosis factor receptor superfamily 11B, encodes osteoprotegerin. We report that CCAL1 is highly expressed in osteoarthritis (OA) tissues and Human Chondrocyte‐Osteoarthritis (HC‐OA) cells and its expression level is positively correlated with the severity of OA. CCAL1 could activate NF‐κB and inhibit AMPK pathways to promote HC‐OA cell fibrosis, viability and proliferation., Osteoarthritis (OA) is a chronic joint disease characterized by articular cartilage degeneration and secondary osteogenesis. It has been previously demonstrated that the CCAL1 locus is the gene encoding tumor necrosis factor receptor superfamily member 11B (TNFRSF11B). The purpose of this study was to demonstrate the role of CCAL1 in OA progression and to elucidate its molecular mechanisms. We report that CCAL1 is highly expressed in the cartilage of OA patients and its expression level is positively correlated with the severity of OA. We found that CCAL1 causes a switch to the fibrosis‐prone phenotype of Human Chondrocyte‐Osteoarthritis (HC‐OA) cells. In addition, CCAL1 enhances cell viability and promotes the proliferation of HC‐OA cells. Finally, the detection of proteins associated with the NF‐κB/AMPK signaling pathway by western blot suggested that CCAL1 exerts its role on HC‐OA cells by activating the NF‐κB signaling pathway and inhibiting the AMPK signaling pathway, which was verified through the addition of NF‐κB inhibitor caffeic acid phenethyl ester (CAPE) and AMPK activator 5‐aminoimidazole‐4‐carboxamide riboside (AICAR). In summary, we report that CCAL1 may promote OA through the NF‐κB and AMPK signaling pathways.

Understanding the key factors influencing the mechanical and electrical properties of semiconducting polymers is crucial to the development of stretchable electronics. In this work, a high-mobility...

Commercial applications of skin-like electronic devices for healthcare, intelligent robotics and electronic communication require large-scale high-density transistor arrays with high mechanical deformability and robustness that can be provided by intrinsically stretchable transistors. However, the contradictory crystallinity-dominated mobility and stretchability in the currently reported polymer semiconductors result in extremely limited high-mobility intrinsically stretchable transistors. Herein, based on a polymer with strong intrachain transport, we pioneer the use of molecular weight modulation to synchronously achieve increased mobility from 0.56 to 1.95 cm2 V−1 s−1 and increased crack-onset strain from 26 to 97% in the PIDTBT film. Based on the molecular weight modulation, a high-performance intrinsically stretchable transistor array with stretchability up to 100 percent strain and mobility up to 1.84 cm2 V−1 s−1, was demonstrated. Moreover, the stretchable transistor array presents a device density as high as 375 devices per square centimeter and good electrical performance at the static and dynamic stretching strain. Our results provide a new strategy for creating intrinsically stretchable transistors with high mobility and present unprecedented opportunities for large-scale high-density production of next-generation stretchable electronics.

By reactive DC magnetron sputtering from a pure Ta target onto silicon substrates, Ta(N) films were prepared with a different N2 flow rate of 0, 12, 17, 25, 38, 58 sccm. The effects of N2 flow rate on the electrical properties, crystal structure, elemental composition and optical properties of Ta(N) were studied. These properties were characterized by the four-probe method, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). Results show that the deposition rate decreases with an increase of the N2 flows. On the other hand, the resistivity increases, the crystal size decreases, and the crystal structure transitions from β-Ta to TaN(111), and finally becomes the N-rich phase Ta3N5 (130,040). Studying the optical properties, it is found that there are differences in the refractive index (n) and extinction coefficient (k) of Ta(N) with different thicknesses and different N2 flow rates, and dependent on the crystal size and crystal phase structure.

Dysregulation of long non-coding RNA (IncRNA) antisense non-coding RNA in the INK4 locus (ANRIL) is associated with the risk of myocardial infarction (MI). Therefore, the present study aimed to determine the mechanisms underlying this association, which is currently poorly understood, to the best of our knowledge. The current study used an in vitro myocardial ischemia and reperfusion (MI/R) model, in which H9c2 cardiomyocytes were exposed to hypoxia/reoxygenation (H/R), which demonstrated that ANRIL expression was downregulated and that ANRIL positively regulated sirtuin 1 (SIRT1) expression following H/R injury. Subsequently, it was demonstrated that ANRIL upregulated SIRT1 expression by sponging microRNA-181a (miR-181a). In addition, ANRIL overexpression reduced lactate dehydrogenase release and apoptosis of H9c2 cardiomyocytes exposed to H/R, indicating that ANRIL prevented H/R-induced cardiomyocyte injury. Moreover, both miR-181a overexpression and SIRT1 knockdown significantly decreased the protective effects of ANRIL on H/R-induced cardiomyocyte injury, thus demonstrating that SIRT1 upregulation via sponging miR-181a is a critical mechanism that mediates the function of ANRIL. These results provided a novel mechanistic insight into the role of ANRIL in H/R-injured cardiomyocytes and suggested that the ANRIL/miR-181a/SIRT1 axis may be a therapeutic target for reducing MI/R injury.

Four wide bandgap donor-acceptor (D-A) conjugated polymers, i.e. P-diF2T, P-TT, P-BDT and P-NDT, with bis(5-(2-decyltetradecyl)-[2,3′-bithiophen]-2′-yl)arylenes as D-units and 2-propyl-5,6-difluorobenzo[d][1,2,3]triazole (ffTAZ) as A unit were synthesized for photovoltaic applications. In P-diF2T, P-TT, P-BDT and P-NDT, 3,3′-difluoro-2,2′-bithiophene (diF2T), thieno[3,2-b]thiophene (TT), benzo[1,2-b:4,5-b']dithiophene (BDT) and naphtho[1,2-b:5,6-b']dithiophene (NDT) were used as aryl central units, respectively, to adjust the properties of the polymers. The optical bandgap is 1.83 eV for P-diF2T, 1.85 eV for P-TT, 1.90 eV for P-BDT and 2.04 eV for P-NDT. All four polymers show temperature-dependent aggregation behavior in solution, and their absorption spectra are complementary with that of non-fullerene acceptor (NFA) 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(5-hexylthiophen-2-yl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene (ITIC-Th). Polymer solar cells (PSCs) based on these polymers and ITIC-Th were fabricated and characterized. Power conversion efficiencies (PCEs) higher than 7% were demonstrated for all polymers. The devices based on P-diF2T exhibited the highest PCE up to 10.08% with a high fill factor (FF) of 0.741. The good photovoltaic performance of P-diF2T is attributed to the synergies of the low-lying highest occupied molecular orbital (HOMO) energy level of the polymer and the favorable microstructures and morphology and thereby high and balanced charge carrier mobilities of the blend films. This study suggested that adjusting aromatic D units together with using alkylthiophene as side chains is an effective approach to design donor polymers for high performance PSCs based on NFA.

Two isomeric 2-hexyl substituted five-ring-fused asymmetric thienoacenes, i.e., thieno[1]benzothieno[3,2-b][1]benzothiophene (BTBTT6), in which the S atom in the terminal thiophene ring is located at different positions relative to the BTBT core, were synthesized and characterized. The syn-isomer forms bilayer “head-to-head” structures with herringbone packing modes within the layers in crystals, while the anti-isomer shows “head-to-tail” single-layer structures and sandwich-herringbone packing within the layers. The difference in packing structures involved the fact that the syn-isomer has stronger intermolecular interactions than the anti-isomer. Importantly, organic thin-film transistors (OTFTs) with near-ideal transfer and output characteristics were fabricated. Mobilities in the saturation and the linear regime (μsat and μlin) of up to 11.7 and 10.6 cm2 V−1 s−1, respectively, were achieved for the syn-isomer. This is the first report on OTFTs with both μsat and μlin above 10 cm2 V−1 s−1.

Recent advances in material design for organic solar cells (OSCs) are primarily focused on developing near-infrared non-fullerene acceptors, typically A-DA D-A type acceptors (where A abbreviates an electron-withdrawing moiety and D, an electron-donor moiety), to achieve high external quantum efficiency while maintaining low voltage loss. However, the charge transport is still constrained by unfavorable molecular conformations, resulting in high energetic disorder and limiting the device performance. Here, a facile design strategy is reported by introducing the "wing" (alkyl chains) at the terminal of the DA D central core of the A-DA D-A type acceptor to achieve a favorable and ordered molecular orientation and therefore facilitate charge carrier transport. Benefitting from the reduced disorder, the electron mobilities could be significantly enhanced for the "wing"-containing molecules. By carefully changing the length of alkyl chains, the mobility of acceptor has been tuned to match with that of donor, leading to a minimized charge imbalance factor and a high fill factor (FF). We further provide useful design strategies for highly efficient OSCs with high FF. Funding Agencies|National Key Research & Development Projects of China [2017YFA0206600]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China [21875286]; Science Fund for Distinguished Young Scholars of Hunan ProvinceNational Natural Science Foundation of ChinaNational Science Fund for Distinguished Young Scholars [2017JJ1029]; Innovation-Driven Project of Central South University [2020CX001]; Research Committee of HKBU [RC-ICRS/15-16/4A-SSK, FRG/16-17/077]

Four bisisoindigo (bis-IID) derivatives containing different numbers of electron withdrawing fluorine (F) or nitrogen (N) atoms and eight alternating copolymers of them with 2,2′-bithophene (BT) or 3,3′,4,4′-tetrafluoro-2,2′-bithiophene (4FBT) were synthesized. Depending on the numbers of F and N atoms incorporated, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels of the polymers were feasibly tuned in the ranges of −5.51 to −6.06 eV and −3.64 to −4.01 eV, respectively. Top gate and bottom contact (TGBC) organic thin-film transistors (OTFTs) were fabricated to study the semiconducting properties of the polymers. Five polymers, i.e., P0F-BT, P2F-BT, P4F-BT, P2N2F-BT, and P0F-4FBT that contain 0–4 F and N atoms in the repeating unit, with HOMO and LUMO energy levels above −5.90 and −3.80 eV, respectively, all showed ambipolar OTFT characteristics. Three other polymers P2F-4FBT, P4F-4FBT, and P2N2F-4FBT that contain 6 or 8 F and N atoms with HOMO ...

A series of naphthalene carbohydrazone based fluorescent chemosensors L1-L4 were developed for the detection of Zn2+ by significant fluorescence enhancement. The binding ratio of the L1-Zn2+ complex was determined by a Job’s plot to be 1:1 and confirmed by ESI–MS studies. The corresponding of the L1-Zn2+ ensemble was elucidated through X-ray crystallography along with spectroscopic studies. Furthermore, the LX-Zn2+ (X = 1–2) complexes can specifically detect pyrophosphate (PPi) in HEPES buffer solution through fluorescence quenching. The detection limit of LX-Zn2+ (X = 1–2) for PPi sensing were calculated to be as low as 2.54 ppb and 0.94 ppb, respectively. In addition, due to their good cell membrane permeability and low cytotoxicity, L1-L4 have been applied to sequentially detect Zn2+ and PPi in living cells. More importantly, the electronic effect of substitute groups on fluorescence signaling have been studied by substituent properties ranging from electron-donating to electron-withdrawing, which sets up a promising strategy for the rational design of fluorescent sensors.

Due to their strong intermolecular interactions, polymer semiconductors aggregate in solution even at elevated temperature. With the aim to study the effect of this kind preaggregation on the order of thin films and further transistor performance, bi-thieno[3,4-c]pyrrole-4,6-dione and fluorinated oligothiophene copolymerized polymer semiconductor P1, which shows strong temperature-dependent aggregation behavior in solution, is synthesized. Its films are deposited through a temperature-controlled dip-coating technique. X-ray diffraction and atomic force microscopy results reveal that the aggregation behavior of P1 in solution affects the microstructures and order of P1 films. The charge transport properties of P1 films are investigated with bottom-gate top-contacted thin-film transistors. The variation of device performance (from 0.014 to 1.03 cm2 V–1 s–1) demonstrates the importance of optimizing preaggregation degree. The correlation between preaggregation degree and transistor performance of P1 films is explored.

We herein report the synthesis and characterization of four asymmetric conjugated oligomers based on polycyclic aromatics, i.e. , 2-(5-hexylselenophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene (BTBT-S6), 2-(5-hexylfuryl-2-yl)[1]benzothieno[3,2-b][1]benzothiophene (BTBT-F6), 2-(5-hexylselenophen-2-yl)[1]benzoselenopheno[3,2-b][1]benzoselenophene (BSBS-S6) and 2-(5-hexylfuryl-2-yl)[1]benzofuro[3,2-b][1]benzofuran (BFBF-F6), for elucidating the influence of chalcogens on molecular geometries, electronic structures, thin film microstructures and the performance of organic thin-film transistors (OTFTs). Compared to the previously reported analogue 2-(5-hexylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene (BTBT-T6), all four molecules have higher-lying highest occupied molecular orbital (HOMO) energy levels. BTBT-S6 and BSBS-S6 (S replaced by Se atoms) display similar mesomorphic behavior and packing motif in solid state. However, BSBS-S6 shows much poorer crystallinity. Only crystal phase was observed for BTBT-F6 and BFBF-F6 (S replaced by O atoms). These two molecules also adopt the molecular arrangements, film growth modes and film morphology distinct from BTBT-S6 and BSBS-S6. Thus, the four molecules exhibited very different OTFT performance. BTBT-S6 showed the highest mobility of 4.68 cm 2 V −1 s −1 and all other three compounds exhibited mobilites lower than 1 cm 2 V −1 s −1 .

Hydrazine has been identified as an environmental contaminant and a probable human carcinogen for its high toxicity. Thus, the development of detection methods for mapping hydrazine in solution and biosystems, particularly in vivo, is of great significance. Here, through firstly exploited 2-thiophenecarbonyl moiety as a recognition unit for hydrazine, a novel near-infrared (NIR) fluorescent probe CyOS is obtained based on hemicyanine. The probe shows high selectivity towards hydrazine over various amino acids and common ions with a significant fluorescence enhancement at 701 nm in the presence of hydrazine. Further, it has a sufficiently low detection limit (0.78 ppb). And most importantly, due to its good cell membrane permeability and low cytotoxicity, CyOS has been applied to monitor and image hydrazine in living cells, tissues and mice. To the best of our knowledge, it is the first time to visualize hydrazine in deep living tissues (∼90 μm).

Herein, a new water soluble Ca2+ fluorescence chemosensor based on aggregation-induced emission (AIE) characteristics has been developed, combining the AIE effect of tetraphenylethylene (TPE) and the complexation capability of bidentate pyridine carboxylate. The bidentate pyridine carboxylate group provides the chemosensor with good water-solubility which is important for detection in biological systems. This chemosensor L showed high selectivity for Ca2+ by a turn-on response in almost pure aqueous solution with a detection limit of 51.2 nM. L can be used as a recyclable Ca2+ fluorescent chemosensor in the presence of EDTA. Moreover, the chemosensor L was successfully applied to imaging detection and real-time monitoring of Ca2+ in living cells with low toxicity and good membrane permeability.

The phase separation structure evolution process, i.e. confinement and broke out phenomenon in crystallization/crystallization poly (3-hexylthiophene) (P3HT) and poly [[N,N-bis(2-octyldodecyl)-napthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]- alt-5, 5′-(2,2′-bithiophene)] (N2200) blends were controlled by the polymer solution aggregation behavior and relative crystallization degree of each component. In this study, two different molecular weight of P3HT, Mw = 6 kDa and Mw = 55 kDa were selected and blend with N2200 as the model systems. Different molecular weight of P3HT had different crystalline ability in blend films. A similar phase separation of both two polymer blends could form in good solvent chloroform (CF). Marginal solvents and thermal annealing were employed to change the polymer solution aggregation behavior and relative crystallization degree of the two components. On one hand, when p-xylene (pX) was added as the co-solvent to increase the aggregation of P3HT molecules, for P3HT (Mw = 6 kDa)/N2200, the P3HT phase broke the restriction of N2200 phase while there was almost unchanged in P3HT (Mw = 55 kDa)/N2200. On the other hand, during thermal annealing, the P3HT molecule had a stronger molecular moving ability in P3HT (Mw = 6 kDa)/N2200 than that in P3HT (Mw = 55 kDa)/N2200 (the relative crystallization degree of these two polymers in P3HT (Mw = 6 kDa)/N2200 and P3HT (Mw = 55 kDa)/N2200 are 142 and 3, respectively). The pristine phase separation of P3HT (Mw = 6 kDa)/N2200 was destroyed effectively due to the unmatched crystallization degree of the two components and large sized fibrous phase separation was formed during thermal annealing. However, the pristine phase separation was almost unchanged in P3HT (Mw = 55 kDa)/N2200, and the P3HT molecule could partly ordered arrangement, which probably come from the almost matched crystallization degree of these two polymers. The results indicate that it is the Gibbs free energy that controls the phase separation in different relative crystallization degree. And different chain entanglements behavior was likely to be the main source of the morphological stability.

It's a challenge to prepare high-performance polymer solar cells (PSCs) employing non-halogenated solvents due to the poor solubility of conjugated polymers. Here, a new region-random copolymer, in contrast to traditional polymers featuring a D–A or D–π–A–π backbone, is synthesized and fully characterized. By polymerizing ffBT-T (π–A) units with BDT (D) units, the resultant polymer PBDT-ffBT-T (P1T) with repeat units of D–π–A or D–A–π exhibits superior solubility in non-halogenated solvents and outperforms its traditional analogues with the highest performance of 8.53% when processed from anisole. Importantly, the optimal device performance is attained with an active layer thickness of over 200 nm and shows no batch-to-batch difference, implying its compatibility with printing technology. Our results demonstrate that this simple chemical modification for copolymers may significantly benefit the development of PSCs using environmentally friendly solvents.

Three new alternating copolymers containing 3,3′-dicyano-2,2′-bithiophene (BT2CN), i.e., DPPTh-BT2CN, DPPPy-BT2CN and 2FIID-BT2CN based on diketopyrrolopyrrole (DPP) and isoindigo (IID) derivatives, were synthesized. The properties of these three polymers were compared with those of the reference polymer without a cyano (CN) group, DPPTh-BT. The introduction of CN groups dramatically lowered both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels of the polymers. DPPTh-BT2CN exhibited HOMO and LUMO energy levels of −5.41 and −3.67 eV, respectively, which are much lower than those of the analogue polymer DPPTh-BT comprising a biothiophene (BT) segment. DPPPy-BT2CN and 2FIID-BT2CN showed even lower HOMO and LUMO levels, which are −5.83 and −3.75 eV for DPPPy-BT2CN and −6.15 and −3.92 eV for 2FIID-BT2CN. Organic thin-film transistors (OTFTs) were fabricated to evaluate the semiconducting properties of the polymers. DPPTh-BT2CN-based OTFTs exhibited electron-dominant transport characteristics, similar to the devices based on the benchmark n-type conjugated polymer N2200. By contrast, DPPPy-BT2CN and 2FIID-BT2CN-based devices displayed pure n-channel characteristics due to their lower HOMO and LUMO levels. All three polymers displayed an electron mobility (μe) of ca. 0.3 cm2 V−1 s−1, which is comparable to that of N2200 when the same device structure and measurement conditions were adopted.

Organic semiconductors integrating excellent charge transport with efficient solid emission are very challenging to be attained in the construction of light-emitting transistors and even for realization of electrically pumped organic lasers. Herein, we introduce naphthyl units at 2,6-positions of anthracene to achieve 2,6-di(2-naphthyl)anthracene (dNaAnt), which adopts J-aggregated mode in the solid state as a balanced strategy for excellent charge transporting and efficient solid state emission. Single crystal field-effect transistors show mobility up to 12.3 cm2·V–1·s–1 and a photoluminescence quantum yield of 29.2% was obtained for dNaAnt crystals. Furthermore, organic light-emitting transistors (OLETs) based on dNaAnt single crystals distribute outstanding balanced ambipolar charge transporting property (μh = 1.10 cm2·V–1·s–1, μe = 0.87 cm2·V–1·s–1) and spatially controllable emission, which is one of the best performances for OLETs.

Polyamic acid (PAA) fiber derived from 3,3′,4,4′-biphenyltetra-carboxylic dianhydride and p -phenylenediamine is prepared via dry-jet wet-spinning method. Polyimide (PI) fibers are obtained by applying two kinds of thermal treatment procedures on the PAA fibers. The evolution of fiber structure during thermal treatments is traced. And the influence of fiber structure on the mechanical properties is also studied. In Procedure I, the PAA fibers are heated from room temperature to 400 °C at 5 °C/min. As temperature increases from room temperature to 125 °C, relaxation behavior of PAA chains happens at first. Then, from 125 to 300 °C, imidization reaction occurs. Meanwhile, before the temperature reaches 250 °C, a significant degradation of PAA chains exists and makes the fibers too weak to measure. Crystals in fiber begin to form as temperature exceeds 250 °C and totally complete at 350 °C. The fracture strength and initial modulus of fiber are significantly improved with the formation of crystals and finally reach 0.83 GPa and 48.4 GPa at 400 °C, respectively. In Procedure II, the PAA fibers are isothermally treated at 250, 300, 350 and 400 °C for different times. When treated at 400 and 350 °C, both imidization and crystallization in fiber can happen simultaneously and complete in tens of seconds because of the high mobility of the polymer chains. While as treated at 300 and 250 °C, both these two processes are slowed down and the formation of crystals lags behind the imidization process. High crystallinity can be obtained under higher treatment temperature in a very short time. The mechanical properties of fiber highly depend on the treatment temperature rather than the treatment time. The fibers treated at 400 °C for 60 s show the highest fracture strength and initial modulus of 1.4 GPa and 70.0 GPa, respectively.

Herein, we report the synthesis and characterization of a series of [1]benzothieno[3,2-b][1]benzothiophene (BTBT)-based asymmetric conjugated molecules, that is, 2-(5-alkylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene (BTBT-Tn, in which T and n represent thiophene and the number of carbons in the alkyl group, respectively). All of the molecules with n ≥ 4 show mesomorphism and display smectic A, smectic B (n = 4), or smectic E (n > 4) phases and then crystalline phases in succession upon cooling from the isotropic state. Alkyl chain length has a noticeable influence on the microstructures of vacuum-deposited films and therefore on the performance of the organic thin-film transistors (OTFTs). All molecules except for 2-(thiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene and 2-(5-ethylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene showed OTFT mobilities above 5 cm2 V–1 s–1. 2-(5-Hexylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene and 2-(5-heptylthiophen-2-yl)[1]benzothieno[3,2-b][1]benz...

High-efficiency ternary polymer solar cells (PSCs) are fabricated by using two donor polymers (PBDTTPD and PBDTTT-C-T) with similar polymer backbones and complementary absorption and PC71BM as the acceptor. A high power conversion efficiency (PCE) of 9.3% is achieved with a high short-circuit current density (J(sc)) of 17.2 mA cm(-2). The enhanced J(sc) and PCEs are mainly attributed to the broadened photoresponse of the ternary blend. Good miscibility of the two donor polymers is found due to the similar polymer main chains, leading to the desired morphology between the donors and PC71BM in the ternary blends. The trend of open-circuit voltage (V-oc) variations indicates the formation of a polymer alloy in this ternary blend. Our work demonstrates that using two donor polymers with similar backbone structures is a rational strategy for realizing high-performance ternary PSCs.

Growth of rubrene thin films at room temperature on bare SiO 2 substrates and on top of a α-quaterthiophene (α-4T) inducing layer on SiO 2 substrates was investigated. The rubrene thin films and α-4T inducing layers were prepared by vacuum deposition method and were characterized by atomic force microscopy and X-ray diffraction. Rubrene thin films directly deposited on SiO 2 substrates had a number of holes on their surface, while the ones grown on top of a α-4T inducing layer on SiO 2 substrates exhibited highly ordered morphology and structure. It was found that large-area and ordered rubrene thin films could properly match with the α-4T inducing layers in the prepared heterostructures. Two different rubrene film growth mechanisms were observed from results obtained for films with different thicknesses. We conclude that rubrene thin films prepared at low temperature using α-4T inducing layer on SiO 2 substrates hold a great promise of application in large-area and flexible displays.

Two new wide-bandgap polythiophenes, i.e., poly[5,5′-bis(2-hexyldecyl)-(2,2′-bithiophene)-4,4′-dicarboxylate-alt-5,5′-3-chloro-2,2′-bithiophene] (PDCBT-Cl) and poly[5,5′-bis(2-hexyldecyl)-(2,2′-bithiophene)-4,4′-dicarboxylate-alt-5,5′-3,3′-dichloro-2,2′-bithiophene] (PDCBT-2Cl) comprising 3-chloro-2,2′-bithiophene and 3,3′-dichloro-2,2′-bithiophene moieties, respectively, were synthesized for fullerene-free polymer solar cells (PSCs). For comparison, three other polymers based on [2,2′-bithiophene]-4,4′-dicarboxylate (DCBT), i.e., PDCBT, PDCBT-F, and PDCBT-2F with 2,2′-bithiophene, 3-fluoro-2,2′-bithiophene, and 3,3′-difluoro-2,2′-bithiophene as comonomers, respectively, were also prepared. PSC devices were fabricated with these polymers as donor materials and ITIC-Th1 as acceptor. The incorporation of chlorine (Cl) or fluorine (F) atoms into polymers both efficiently downshifted the highest occupied molecular orbital (HOMO) energy levels, leading to higher open-circuit voltage (Voc) in the PSCs. Owing to the proper phase-separated morphology with favorable molecular packing and miscibility, the device based on PDCBT-Cl:ITIC-Th1 exhibited efficient exciton dissociation and charge collection as well as weak charge recombination and thereby displayed the best power conversion efficiency (PCE) up to 12.38%. The devices based on other polymers showed inferior PCEs (8.14% for PDCBT, 10.85% for PDCBT-F, 8.48% for PDCBT-2F, and 6.94% for PDCBT-2Cl). The monomers that are used to make PDCBT-Cl can be synthesized in relatively large scale from commercial available chemicals. All these indicate that PDCBT-Cl is a promising donor material for the large area fabrication of high-performance fullerene-free PSCs.

Efficient organic solar cells (OSCs) often use combination of polymer donor and small molecule acceptor. Herein we demonstrate efficient and thermally stable OSCs with combination of small molecule donor and polymer acceptor, which is expected to expand the research field of OSCs. Typical small molecule donors show strong intermolecular interactions and high crystallinity, and consequently do not match polymer acceptors because of large-size phase separation. We develop a small molecule donor with suppressed π-π stacking between molecular backbones by introducing large steric hindrance. As the result, the OSC exhibits small-size phase separation in the active layer and shows a power conversion efficiency of 8.0%. Moreover, this OSC exhibits much improved thermal stability, i.e. maintaining 89% of its initial efficiency after thermal annealing the active layer at 180 °C for 7 days. These results indicate a different kind of efficient and stable OSCs., The organic solar cells are typically based on a binary combination of polymeric donor and molecular acceptor. Here Zhang et al. develop alternative combination based on molecular donor and polymeric acceptor featuring 8% efficiency and high stability up to 7 days at 180 °C.

Noncoding RNAs (ncRNAs) are implicated in various biological processes. Recent findings have demonstrated that the function of ncRNAs correlates with their provenance. Therefore, the recognition of ncRNAs from different organelle genomes will be helpful to understand their molecular functions. However, the weakness of experimental techniques limits the progress toward studying organellar ncRNAs and their functional relevance. As a complement of experiments, computational method provides an important choice to identify ncRNA in different organelles. Thus, a computational model was developed to identify ncRNAs from kinetoplast and mitochondrion organelle genomes. In this model, RNA sequences are encoded by "pseudo dinucleotide composition." It was observed by the jackknife test that the overall success rate achieved by the proposed model was 90.08 %. We hope that the proposed method will be helpful in predicting ncRNA organellar locations.

We demonstrated the crystallization assisted microphase separation of all-conjugated diblock copolymers poly (2,5-dihexyloxy- p -phenylene)-block-(3-hexylthiophene) (PPP-b-P3HT, denoted as BmTn). The crystallization and microphase separation are summarized in terms of the difference of aggregation in solvent and the crystallization temperatures of two blocks, respectively. B39T18 and B41T44 were selected, and crystalline nanowires were formed for B39T18 cast from non-selective solvent via the crystallization of PPP block overwhelming P3HT block. However, both microphase separation and crystallization occurred from selective solvent for PPP block, due to the enhanced aggregation of P3HT block governed by solvophobic interactions. The morphological evolution of B41T44 with equivalent crystallization capacity displayed an opposite result. The lamellar nanostructures formed in films were cast from non-selective solvent and the crystallization breakout microphase separation was formed from selective solvent. Besides, the evolution and phase transition in the thermal annealing process indicated that the PPP crystallized confined from the molten in the P3HT crystalline region, and then the P3HT breakout crystallized primarily and microphase separation with the molten PPP occurred.

A new metastable solvent-induced clathrate liquid crystalline phase of beta phase (named beta' here) in crystalline poly(9,9-dioctylfluorene) (PFO) thin film induced by solvent annealing is found by a combination of in situ ultraviolet and visible spectrophotometry (UV-vis), photoluminescence spectroscopy (PL), and grazing incidence wide-angle X-ray scattering (GIWAXS). The solvent annealing process consists of three processes: diffusion of solvent molecules into the film; saturation of solvent in the film; and drying of the film under nitrogen. The formation of beta' phase with ordered packing of side chains and disordered packing of backbones occurs during the diffusion process of solvent molecules into the film. When the solvent molecules penetrate the film, the disordered side chains start to align themselves to form an ordered structure, and the ordering would gradually in the saturation-process. Furthermore, the ordering of side chains drives an ordered rearrangement of the backbones during the drying process; however, the crystallinity of the side chains decreases with the orderly rearrangement of backbones due to the helical conformation of PFO.

The selection of sensitizer and its existence in the blend films are important to the performance of all-polymer ternary solar cells. Herein, all-polymer ternary solar cell devices, which used poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′] dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxy-late] (PTB7-Th) as donor, poly[[N,N-bis(2-octyldodecyl)-napthalene-1,4,5,8-bis(dicarboximide)−2,6-diyl]-alt-5, 5′-(2,2′-bithiophene)] (N2200) as acceptor and poly[N−900-hepta-decanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole) (PCDTBT) as sensitizer, are successfully demonstrated. The intermolecular interaction between donor PTB7-Th and sensitizer PCDTBT may lead to aggregation of PTB7-Th which decreases domain sizes and enlarges D/A effective interface area. In addition, the PCDTBT molecules also extend light absorption and cascaded energy levels of the ternary blend system. As a result, with 15% PCDTBT we get a power conversion efficiency of 5.11%, almost 20% higher than control device due to more favored exciton dissociation and higher charge transport efficiency. This study reveals a promising way to achieve high efficiency all-polymer solar cells using a low-band gap polymer PCDTBT. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1811–1819

Dopamine is a neurotransmitter, whose concentration change causes various nervous system disorders such as Parkinson’s disease. In this study, hydroxyethyl methacrylate-functionalized graphene oxide was prepared and used as the substrate for matrix-assisted laser desorption/ionization (MALDI) for the mass spectrometric determination of dopamine. The results show that hydroxyethyl methacrylate-functionalized graphene oxide materials may be used as a matrix for MALDI. This approach combines enrichment and detection in a single step. The new method greatly shortens the analysis time and significantly reduces the amount of sample required for the analysis. The detection limit of the method was 20 ng/mL. These features not only ensure that the method is suitable for trace analysis, but also extend the range of application of MALDI analysis to biochemical science.

A polycyclic aromatic unit comprising six rings, i.e., 5,11-bis(2-octyldodecyl)dithieno[3,2-b:3′,2′-b′]naphtho[1,2-b:5,6-b′]dithiophene (DTNDT), was developed. Four donor–acceptor (D–A) conjugated polymers, which are named P-BT, P-2FBT, P-IID, and P-DPP, were synthesized with DTNDT as the D-unit and 2,1,3-benzothiadiazole (BT), 5,6-difluorobenzo[c][1,2,5]thiadiazole (2FBT), isoindigo (IID), and diketopyrrolopyrrole (DPP) as the A-unit, respectively. All four polymers are thermally stable with decomposition temperature above 390 °C and show pseudo-straight-shaped backbones. Their ordered thin films were prepared via solution spin-casting, in which conjugated backbones mainly adopted edge-on alignment on the substrate. The semiconducting properties of the polymers were characterized with bottom gate and top contact (BGTC) organic thin film transistors (OTFTs). All four polymers showed p-type transport behavior, and the hole mobilities were 0.023, 0.078, 0.50, and 1.80 cm2/(V s) for P-BT, P-2FBT, P-IID, and ...

The morphology of the active layer is at the heart of perovskite solar cells. It is deeply related to charge transport and extraction, which depend on coverage ratio, crystallinity, crystal size and perhaps crystal orientation. However, the crystallization process in a solution-processed perovskite film is ungovernable and there is no clear guideline for how to improve the film morphology. Here, we employed the selective solvent annealing (SSA) method to control crystallization kinetics, producing a flat CH3NH3PbIxCl3−x film with almost full coverage, micron scale grain size, enhanced crystallinity and optimized crystal orientation. The improved morphology is attributed to the formation of a uniformly distributed nucleus of perovskite before thermal annealing, resulting from the selective solubility of selective solvents, which accelerates the crystallization of lead iodide (PbI2) and the intercalation of methylammonium iodide (MAI) into the PbI2 crystal lattice. Furthermore, driven by thermodynamics, the nucleus tends to rearrange during the thermal annealing process, and thus the crystal orientation turns from (h k 0) (h = k) to (h 0 0) orientation, which enables the corner of the inorganic framework to come into contact with the substrate. The enhanced crystallinity, enlarged crystal size and optimized crystal orientation are beneficial for the carrier collection due to the prolonged carrier life time and reduced carrier recombination, which resulted in the highest power conversion efficiency (PCE) of 12.38%, about 37% increase compared with the reference device.

In the design of high performance conjugated copolymers, π-spacer plays one of the most important roles in finely manipulating photovoltaic properties of the polymers. However, up to now, little attention has been paid to functionalize the π-spacer. In this work, a novel D–A conjugated copolymer PBTI3T-S, with 3-(decylthio)thiophene as the π-spacer, is designed and synthesized. The introduction of a modified π-spacer has little influence on the absorption spectrum and band gap of the polymer. However, it is found that the modified π-spacer could create a noncovalent attractive interaction between neighboring moieties, resulting in good planarity and decreased π–π stacking distance in comparison to its analogue PBTI3T with decyl substitution on the π-spacers. More interestingly, the face-on population of crystallite orientation is significantly enhanced. Thus, the hole mobility of the PBTI3T-S/PC71BM blend is 1.29 × 10−2 cm2 V−1 s−1, which is one order of magnitude higher than that of the PBTI3T/PC71BM blend (1.15 × 10−3 cm2 V−1 s−1). The PBTI3T-S device provides a higher PCE of 7.14%, while the optimized PBTI3T device provides 6.51%. Impressively, the PCEs of the PBTI3T-S device can remain above 7% without substantial loss as the active layer thickness increases up to ∼270 nm, while the PCE reduces to 5.70% for the PBTI3T. These results demonstrate that the introduction of an alkylthio chain modified π-spacer would be an effective way to further improve the device performance and provide a guideline for molecular engineering towards the application of the roll to roll printing technique.

Solution-processing rubrene crystals were fabricated by blending an amount of high-boiling-point solvent into a dilute solution of rubrene in chloroform. The crystallization processes were investigated by the analysis of morphology and crystalline structures. The trajectory to the dendrite-like crystals grown was clearly observed by controlling the ratio of the binary solvent mixtures. Tremendous, compact dendrite-like crystals and sheet-like crystals were obtained by further decreasing the evaporation rate through a drop-casting method. The results indicated that the crystalline process was significantly influenced by the binary solvent ratio and the fabrication method. The crystallinity of rubrene films could be tuned from disorder, with pure chloroform solvent, to high crystallinity, with binary solvent mixtures. The formation mechanism of rubrene crystals was proposed as a competition between the impetus of slow evaporation by high-boiling-point solvent and the self-assembly force of rubrene molecules to the crystal. These results, which exhibit the concrete possibility of growing crystalline and ordered rubrene thin films, open pathways to organic thin film technology and devices.

Modulating the structure and property of hole-transporting organic semiconductors is of paramount importance for high-efficiency and stable perovskite solar cells (PSCs). This work reports a low-cost peri-xanthenoxanthene based small-molecule P1, which is prepared at a total yield of 82 % using a three-step synthetic route from the low-cost starting material 2-naphthol. P1 molecules stack in one-dimensional columnar arrangement characteristic of strong intermolecular π-π interactions, contributing to the formation of a solution-processed, semicrystalline thin-film exhibiting one order of magnitude higher hole mobility than the amorphous one based on the state-of-the art hole-transporter, 2,2-7,7-tetrakis(N,N'-di-paramethoxy-phenylamine 9,9'-spirobifluorene (spiro-OMeTAD). PSCs employing P1 as the hole-transporting layer attain a high efficiency of 19.8 % at the standard AM 1.5 G conditions, and good long-term stability under continuous full sunlight exposure at 40 °C.

N6-methyladenosine (m6A) plays important roles in a branch of biological and physiological processes. Accurate identification of m6A sites is especially helpful for understanding their biological functions. Since the wet-lab techniques are still expensive and time-consuming, it's urgent to develop computational methods to identify m6A sites from primary RNA sequences. Although there are some computational methods for identifying m6A sites, no methods whatsoever are available for detecting m6A sites in microbial genomes. In this study, we developed a computational method for identifying m6A sites in Escherichia coli genome. The accuracies obtained by the proposed method are >90% in both 10-fold cross-validation test and independent dataset test, indicating that the proposed method holds the high potential to become a useful tool for the identification of m6A sites in microbial genomes.

In recent years, rapid advances are achieved in polymer solar cells (PSCs) using nonfullerene small molecular acceptors. However, no research disclosing the influence of molecular weight (Mn ) of conjugated polymer on the nonfullerene device performance is reported. In this work, a series of polymers with different Mn s are synthesized to systematically investigate the connection between Mn and performance of nonfullerene devices for the first time. It is found that the device performance improves substantially as the Mn increases from 12 to 38 kDa and a power conversion efficiency (PCE) as high as 10.5% is realized. It has to be noted this PCE is achieved without using any additives and post-treatments, which is among the top efficiencies of additive- and post-treatment-free PSCs. Most importantly, the variation trend of the optimal active layer thickness and morphology is significantly different from the device with fullerene as acceptor. The findings clarify the effect of Mn on the performance of nonfullerene PSCs, which would benefit further efficiency improvement of nonfullerene PSCs.

Perylene derivatives are a family of well-known organic electron-transporting materials with excellent photochemical and thermal stabilities, and have been widely used in various optoelectronic devices. In this work, two diphenylamine functionalized N-annulated perylenes are reported as hole-transporting materials (HTMs) for perovskite solar cells. Through joint theoretical and experimental studies, the HTM employing a methoxyphenyl lateral substituent is found to feature a closer stacking distance and better aggregate connectivity in the solid film than its analogue with the bulky 2-hexyldecyl lateral substituent, contributing to a higher hole mobility and a remarkably enhanced device performance of perovskite solar cells. This work demonstrates the significant influence of lateral substituents of HTMs on the intermolecular packing and solid microstructure, giving a clear insight on the molecular design of high-performance organic semiconductors.