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Molecular design of either polymer donors or acceptors is a promising strategy to tune the morphology of the active layer of organic solar cells, enabling a high-performance device. Thereinto, developing novel polymer donors is an alternative method to obtain high photovoltaic performance. Herein, we present a facile side-chain engineering on the dithiophenobenzotriazole (DTBTz) unit of newly-designed polymer donors (named pBDT-DTBTz-EH and pBDT-DTBTz-Me) to boost the performance of non-fullerene solar cells. Compared with pBDT-DTBTz-EH with long N-alkyl side chains, pBDT-DTBTz-Me with a short methyl exhibits stronger molecular aggregation, higher absorption coefficient, and preferred face-on orientation packing. As a consequence, pBDT-DTBTz-Me based devices achieve an optimal power conversion efficiency of 15.31% when donors are paired with the narrow bandgap acceptor Y6, which is superior to that of pBDT-DTBTz-EH based devices (9.17%). Additionally, the pBDT-DTBTz-Me based devices manifest more effective charge separation and transfer than pBDT-DTBTz-EH based devices. These results indicate that fine-tuning side chains of polymer donors provide new insights for the design of high-performance polymer donors in non-fullerene solar cells.

The employment of an intrinsic quinoidal building block, benzodipyrrolidone (BDP), on constructing conjugated polymers (PBDP-2F and PBDP-2CN) with high electron mobility and unipolar transport characteristic in polyethylenimine ethoxylated (PEIE) modified organic field-effect transistors (OFETs) is reported. The intrinsic quinoidal characteristic and excellent co-planarity of BDP can lower the lowest unoccupied molecular orbital (LUMO) levels and improve ordered interchain packing of the resulting polymers in solid states, which are favorable for electron-injection and transport. By using PEIE as the interlayer to block the hole injection, unipolar n-type transport characteristics with high electron mobility of 0.58 and 1.01 cm2 V−1 s−1 were achieved by the OFETs based on PBDP-2F and PBDP-2CN, respectively. More importantly, the extracted mobilities are highly reliable with the reliability factor of above 80%. To the best of our knowledge, PBDP-2CN is the very first quinoid-based conjugated polymer with reliable electron mobility exceeding 1 cm2 V−1 s−1. This work represents a significant step in exploring intrinsic quinoidal CPs for application in n channel OFETs and logic complementary circuits.

The nucleation of single hydrogen (H2) nanobubbles is explored in Ag nanoelectrodes (NEs, radius is 5–65 nm), where H2 is produced through proton electroreduction in H2SO4 solution. Moreover, Ag NE...

Developing novel building blocks is essentially important to construct high-performance non-fullerene electron acceptors (NFEAs). Benzotrithiophene (BTT) as an electron-donating block has been widely applied in active materials to obtain high-performance organic field-effect transistors. However, its application in NFEAs for organic solar cells (OSCs) has rarely been reported so far. In this work, two NFEAs, BTTBo-4F and BTTBo-4FN, were synthesized by combining BTT as a central unit with two terminal groups. Compared with BTTBo-4F, BTTBo-4FN exhibited stronger absorption, a narrower optical bandgap, and more ordered face-to-face π-stacking. As a consequence, the BTTBo-4FN-based OSCs achieved a higher power conversion efficiency (PCE) of 11.60%, whereas the BTTBo-4F-based OSCs achieved a moderate PCE of 8.27%. Further investigation revealed that the BTTBo-4FN-based OSCs exhibited a more efficient charge transfer, lower charge recombination, higher charge mobility, and better phase morphology than the latter. Our findings indicate that combining BTT as a central unit with π-extension terminal groups is a promising strategy to construct high-performance NFEAs.

In this study, a series of large-bandgap polymer donors comprising dithieno[3′,2′:3,4;2′′,3′′:5,6]benzo[1,2-c][1,2,5]thiadiazole (fDTBT) and benzo[1,2-b:4,5-b′]dithiophene units with or without sulfur/fluorine substitution in the side-chains are designed. It is found that the energy levels of these polymer donors can be linearly tuned due to the π-accepting properties of the sulfur atom and strong electron-withdrawing ability of the fluorine atom, while the absorption spectra keep nearly unchanged, which offers us the opportunity to balance the open-circuit voltage and charge separation driving force in all-polymer solar cells (all-PSCs). The device performances of these polymer donors are validated by combining them with the polymer acceptor PJ1. The device results indicate that as the energy-level offsets are increased, these systems exhibit a more efficient charge transfer and lesser charge recombination, which afford remarkably improved short-circuit current density, fill factors, and power conversion efficiency (PCE). Eventually, high-efficiency binary all-PSCs with a maximum efficiency of 15.8% are obtained, which is the highest value reported so far for all-PSCs. Moreover, this system demonstrates superior performance for 1 cm2 all-PSC devices with a PCE of 14.4% and semitransparent all-PSC devices with a PCE of 10.3% (with average visible-light transmittance of 21.5%). Our study manifests that these fDTBT-based polymers are promising donor candidates for high-performance all-PSCs toward practical applications.

In this contribution, we report a novel pyridinium-pended conjugated polyelectrolyte (DPTFBr) for application in photocatalytic hydrogen evolution and organic solar cells. DPTFBr contains pyridinium salts attached to its backbone, which enable its transition from the pristine state to a radical state in the presence of amines and under illumination via a photo-induced amine doping process. The transition results in apparent shifts in the UV-vis absorption spectrum, electrochemical redox potential, and electron spin resonance of the resulting polymer. The unique properties of DPTFBr facilitate its application in photocatalytic hydrogen evolution with a high photocatalytic hydrogen evolution rate of 7.33 mmol g−1 h−1, which is 63- and 12-fold higher than those of its neutral and oxidized analogues, respectively. Additionally, the excellent interface modification capabilities of the pyridinium side chains in DPTFBr enable efficient electron transport/collection, thus giving rise to high-performance organic solar cells with a power conversion efficiency of over 16%.

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is one of the most widely used hole transporting materials in organic solar cells (OSCs). Multiple strategies have been adopted to improve the conductivity of PEDOT:PSS, however, effective strategy that can optimize the conductivity, work function, and surface energy simultaneously to reach a better energy alignment and interface contact is rare. Here, we demonstrate that oxoammonium salts (TEMPO+X−) with different counterions can act as facile and novel dopants to realize secondary doping of PEDOT:PSS. The effective charge transfer process achieved between TEMPO+X− and PEDOT:PSS results in enhanced carrier density and improved conductivity of PEDOT:PSS. Moreover, different counterions of TEMPO+X− can tune the work function and surface energy of PEDOT:PSS, enabling improved device performances. The resulting device with PM6:Y6 as the active layer shows a high power conversion efficiency (PCE) over 16%. Moreover, this doping strategy can also be applied to other conjugated polymers such as poly(3-hexylthiophene). This work provides a promising strategy to tune the properties of conjugated polymers through doping, thus effectively boosting the performance of organic solar cells.

Spontaneous imbibition (SI) is an essential method for accelerating mass exchange between fracture and matrix in tight oil reservoirs. However, conventional systems such as brine and surfactant solution have limited imbibition effects, so there is still abundant remaining oil in the matrix. Nanoemulsion holds the most promising potential in improving tight oil recovery owing to the favorable surface activity and nanoscale droplets, but it still lacks economic and facile methods to fabricate nanoemulsions. Therefore, in this paper, we prepared a kind of O/W nanoemulsion of catanionic surfactants with a low dosage of surfactant and energy consumption, which was then used to assess spontaneous imbibition performance in Changqing outcrop cores by experimental and numerical simulation. We have fully considered the possible imbibition mechanisms of nanoemulsion including wettability alteration, IFT reduction, solubilization and emulsification, etc., and successfully applied to the nanoemulsion imbibition model. The model and experimental data were found to be in good agreement. The results showed that the imbibition rate and oil recovery factor of the nanoemulsion in the first 100 hours are lower than that of brine. In the late stage, we observed a longer equilibrium time and a faster and higher oil imbibition process in nanoemulsion with ultralow IFT. Finally, we confirmed that solubilization and emulsification is one of the domiant mechanisms for nanoemulsion imbibition by comparing with the modelling without considering solubilization and emulsification.

The design and synthesis of conjugated semiconducting polymers for photocatalytic hydrogen evolution have engendered intense recent interest. However, most reported organic polymer photocatalysts show a relatively broad band gap with weak light absorption ability in the visible light region, which commonly leads to a low photocatalytic activity under visible light. Herein, we synthesize three novel dithieno[3,2-b:2′,3′-d]thiophene-S,S-dioxide (DTDO) containing conjugated polymer photocatalysts by a facile C–H arylation coupling polymerization reaction. The resulting polymers show a broad visible light absorption range up to 700 nm and a narrow band gap down to 1.81 eV due to the introduction of the DTDO unit. Benefiting from the donor–acceptor polymer structure and the high content of the DTDO unit, the three-dimensional polymer PyDTDO-3 without the addition of a Pt co-catalyst shows an attractive photocatalytic hydrogen evolution rate of 16.32 mmol h−1 g−1 under visible light irradiation, which is much higher than that of most reported organic polymer photocatalysts under visible light., Narrow band gap conjugated polymer photocatalysts containing dithieno[3,2-b:2′,3′-d]thiophene-S,S-dioxide show an attractive photocatalytic hydrogen evolution rate of 16.32 mmol h−1 g−1 under visible light irradiation.

Nano-structured thin films have a variety of applications from waveguides, gaseous sensors to piezoelectric devices. Grazing Incidence Small Angle x-ray Scattering images enable classification of such materials. One challenge is to determine structure information from scattering patterns alone. This paper highlights the design of multiple Convolutional Neural Networks (CNN) to classify nanoparticle orientation in a thin film by learning scattering patterns. The network was trained on several thin films with a success rate of 94%. We demonstrate CNN robustness under different noises as well as demonstrate the potential of our proposed approach as a strategy to decrease scattering pattern analysis time.

In this paper, single Hg nanoelectrodes were prepared by single nucleation/growth of mercury on the surface of single gold nanodisk electrodes, which were fabricated by improved laser-assisted pulling method. The nucleation/growth process was characterized by scanning electron microscopy (SEM), transition electron microscopy (TEM) and electrochemical method. Pb2+ and Cu2+ could be accumulated and melted with single Hg nanoelectrodes (amalgam formed) through preconcentration step, and then two typical anodic waves would be obtained through square-wave anodic stripping voltammetry (SWASV) method. The peak currents were corresponded to the concentration of Pb2+ and Cu2+, and thus the single Hg nanoelectrodes could be used as a kind of novel nanosensor for simultaneous detection of lead and copper with high sensitivity and selectivity.

Conjugated polymers are emerging as promising organic photocatalysts for photocatalytic hydrogen evolution; however, they are suffering from poor water dispersabilities. Herein, this problem is addressed in an easy and green way with the assistance of a biomass-derived material. An amphipathic xylan derivative that can be self-assembled into nanomicelles was employed as carriers to encapsulate a series of conjugated polymers to form uniform composite micelles in water. By this way, the hydrophobic conjugated polymers and their blends were successfully dispersed into water and thus enabling efficient hydrogen evolution. Moreover, the energy level offsets of these conjugated polymers enable the formation of photoinduced charge transfer (PCT) process and fluorescence resonance energy transfer (FRET) process in their composite micelles. The photocatalytic experimental results showed that in these composite micelles, conjugated polymer blends with PCT characteristic delivered much higher photocatalytic hydroge...

In this work, a label-free electrochemical apta-nanosensor was fabricated on a single gold nanodisk electrode (AuNDE) for thrombin sensing with high sensitivity via a novel signal amplification strategy. This recognition platform was fabricated via self-assembly of helper DNA (HP-DNA), thrombin-binding aptamer (TBA) and gold nanoparticle (AuNP)-DNA complexes to form a sandwich structure on the AuNDE surface. A novel signal amplification strategy via designed AuNP-DNA complexes was introduced using Ru(NH3)63+ as the signal reporter based on the electrostatic interaction. In the presence of thrombin, the strong interaction between the TBA and target led to the dissociation of sandwich DNA complexes from the AuNDE, which resulted in the reduction current of Ru(NH3)63+. This proposed sensing platform showed a wide detection range of 0.1 pM-5 nM and a low detection limit of 0.02 pM. Considering the small overall dimensions and high sensitivity, this nanosensor can be potentially applied for bioanalysis in living biosystems.

High-efficiency organic solar cells (OSCs) largely rely on polymer donors. Herein, we report a new building block BNT and a relevant polymer PBNT-BDD featuring B-N covalent bond for application in OSCs. The BNT unit is synthesized in only 3 steps, leading to the facile synthesis of PBNT-BDD. When blended with a nonfullerene acceptor Y6-BO, PBNT-BDD afforded a power conversion efficiency (PCE) of 16.1 % in an OSC, comparable to the benzo[1,2-b:4,5-b']dithiophene (BDT)-based counterpart. The nonradiative recombination energy loss of 0.19 eV was afforded by PBNT-BDD. PBNT-BDD also exhibited weak crystallinity and appropriate miscibility with Y6-BO, benefitting of morphological stability. The singlet-triplet gap (ΔEST ) of PBNT-BDD is as low as 0.15 eV, which is much lower than those of common organic semiconductors (≥0.6 eV). As a result, the triplet state of PBNT-BDD is higher than the charge transfer (CT) state, which would suppress the recombination via triplet state effectively.

Nonfullerene acceptors (NFAs) have contributed significantly to the progress of organic solar cells (OSCs). However, most NFAs feature a large fused-ring backbone, which usually requires a tedious multiple-step synthesis, and are not applicable to commercial applications. An alternative strategy is to develop nonfused NFAs, which possess synthetic simplicity and facile tunability in optoelectronic properties and solid-state microstructures. In this work, we report two nonfused NFAs, BTCIC and BTCIC-4Cl, based on an A-D-A'-D-A architecture, which possess the same electron-deficient benzothiadiazole central core but different electron-withdrawing terminal groups. The optical properties, energy levels, and molecular crystallinities were finely tuned by changing the terminal groups. Moreover, a decent power conversion efficiency of 9.3 and 10.5% has been achieved by BTCIC and BTCIC-4Cl, respectively, by blending them with an appropriate polymer donor. These results demonstrate the potential of A-D-A'-D-A type nonfused NFAs for high-performance OSCs. Further development of nonfused NFAs will be very fruitful by employing appropriate building blocks and via side-chain optimizations.

In a smoke environment, target recognition is a pivotal problem faced by imaging-guided weapons and reconnaissance equipment. In fact, the transmittance of smoke is the main hindrance to recognition. In this study, a numerical method for extracting pixel radiance to calculate infrared (IR) smoke transmittance is proposed. First, a description of the field test and the equation governing the transmittance of IR smoke are introduced. Next, a method for extracting pixel radiance from an IR image is presented; specifically, a scheme that uses a bicubic interpolation algorithm, to calculate the radiance of the background pixels is presented. Finally, the steps of the method are illustrated through a test example. The results show that the new method eliminates the anomaly of the transmittance value being less than 0 or greater than 1, and in addition, yields sufficiently accurate solutions for engineering applications.

Conjugated polyelectrolytes (CPEs) have achieved vast success in organic electronics due to their appealing opt-electrical properties and convenient solution-processability. However, most of the existing n-type CPEs commonly exhibit distinct light capture in visible region. The attainment of novel n-type CPEs possessing both high electron conductivity and high visible light transparency is significant while still challenging. Herein, optimized amount of organic diradicals achieved by benzobisthiadiazo (BBT) unit are intentionally introduced into the backbone of the representative wide-band-gap polyfluorene-based conjugated polyelectrolyte via ternary copolymerization. The incorporation of diradical canonical structure could promote the quinoid resonance of conjugated skeleton, leading to increased self-doping effect. Consequently, the copolymerized CPE exhibits high visible light transmittance (AVT over 85%) and enhanced electron conductivity compared to the referenced CPE. The fabricated organic solar cell devices with the new-designed polyelectrolyte as the cathode interface layer can achieve high power conversion efficiencies of more than 16%, which is not susceptible to the thickness up to 50 nm. This work provides a feasible molecular modification strategy via organic diradicals regulation to obtain high performance n-type self-doped conjugated polyelectrolytes.

A simple nanopore modification and sensing strategy was developed for the detection of miRNAs. This preparation and sensing approach provides a quick, simple and facile tool for the detection of specific biomolecules with high sensitivity and selectivity, and may find a wide range of applications in bio-analysis.

A nanoprobe for hydrazine sensing is described that is making use of a single gold nanopore electrode (SAuNPEs) that was modified by electro-deposition of Prussian Blue (PB) and then coated with a thin membrane of polypyrrole and carbon dots in order to enhance stability and catalytic activity. Best operated at a low potential of 0.3 V vs. Ag/AgCl, the nanosensor display good electrocatalytic activity towards the oxidation of hydrazine, with a linear response in the 0.5-80 μM hydrazine concentration range and a 0.18 μM detection limit (at S/N = 3). The method was applied to the determination of hydrazine in human urine. Graphical abstract Schematic presentation of the electrocatalytic oxidation of hydrazine using a single gold nanopore electrode that was modified by electro-deposition of Prussian Blue and then coated with a thin membrane of polypyrrole and carbon dots.

The heat loss and cooling modes of a permanent magnet synchronous motor (PMSM) directly affect the its temperature rise. The accurate evaluation and prediction of stator winding temperature is of great significance to the safety and reliability of PMSMs. In order to study the influencing factors of stator winding temperature and prevent motor insulation ageing, insulation burning, permanent magnet demagnetization and other faults caused by high stator winding temperature, we propose a computer model for PMSM temperature prediction. Ambient temperature, coolant temperature, direct-axis voltage, quadrature-axis voltage, motor speed, torque, direct-axis current, quadrature-axis current, permanent magnet surface temperature, stator yoke temperature, and stator tooth temperature are taken as the input, while the stator winding temperature is taken as the output. A deep neural network (DNN) model for PMSM temperature prediction was constructed. The experimental results showed the prediction error of the model (MAE) was 0.1515, the RMSE was 0.2368, the goodness of fit (R2) was 0.9439 and the goodness of fit between the predicted data and the measured data was high. Through comparative experiments, the prediction accuracy of the DNN model proposed in this paper was determined to be better than other models. This model can effectively predict the temperature change of stator winding, provide technical support to temperature early warning systems and ensure safe operation of PMSMs.

Carbon coated CoP hollow spheres (CoP/C) were prepared from cobalt-based MOFs via simple calcining and subsequent phosphorization process. Meanwhile, N-doped carbon shells were also synthesized by a low-cost hard-templating method. Both of the obtained CoP/C and N-doped carbon shells deliver remarkable specific capacitances and excellent capacitance retentions when used as electrodes for supercapacitor. Remarkably, the asymmetric supercapacitor device based on the CoP/C and N-doped carbon shells delivers a high energy density of 16.14 Wh kg−1 at a power density of 700 W kg−1 and outstanding cycling stability (99.5% capacitance retention after 5000 cycles at a current density of 7 A g−1). CoP/C should be a promising electrode material for next-generation supercapacitor application.