Search

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.

Carbon-based anode materials with unique structure, high electrical conductivity, high Li storage performance and excellent cycling stability are promising alternatives to traditional graphite anode materials in lithium-ion batteries (LIBs). Here we report a flower-like carbon material with hierarchical structure that is prepared by carbonization of a flower-like Zn-based metal-organic framework (MOF). The 2D layered MOF network precursor, namely [Zn(BDC)(MelM)·(DMF)] (BDC = benzene dicarboxylic acid, MelM = 2-Methylimidazole), is constructed using two ligands under solvothermal conditions. As an anode material for LIBs, these carbon nanoflakes exhibit remarkable electrochemical performance (capacity, cyclability, and rate capability); the capacity of 902.5 mAh g−1 was retained after 200 cycles at a current density of 100 mA g−1. The remarkable performance results from the unique morphology of carbon nanoflakes which is beneficial for infiltration of electrolyte and the transportation of Li ions.

The D-π-A conjugated polymers with a benzotriazole (BTz) unit as the A moiety have been intensively investigated as donor materials in nonfullerene solar cells. However, these BTz even the fluorinated-BTz constructed D-π-A polymers mostly suffered from upward highest occupied molecular orbital (HOMO) energy levels, leading to inferior open-circuit voltage (VOC) and efficiencies in the fabricated solar cells. Herein, we explored a new approach in response to this issue via the strategy of π-bridge fusion to A moiety. As a result, the medium band gap D-π-A polymer PY2 was evolved into wide band gap D-A polymer PY1 with fused-DTBTz as the new A moiety, accompanied with a greatly declined HOMO energy level by 0.26 eV, a remarkable blue-shifted absorption onset by about 51 nm, and concurrently moderately enhanced face-on stacking orientations in neat polymer and donor/acceptor blend films. The synergetic optimizations in energy level, absorption characteristic and molecular stacking feature via the π-bridge fusion design witness an all-round improvement in photovoltaic parameters including the focused VOC, short-circuit current density (JSC), and fill factor (FF), with narrow band gap ITIC as the acceptor material. Specifically, the PY1-based solar cells produce an optimal power conversion efficiency (PCE) of 12.49%, with superior VOC of 0.94 V, JSC of 18.46 mA cm-2, and FF of 0.72, significantly surpassing those of PY2-based optimal device with a PCE of 7.39%, VOC of 0.77 V, JSC of 14.54 mA cm-2, and FF of 0.66 and even the reported classical fluorinated-BTz based polymer J51 (VOC of 0.82 V, PCE of 9.26%). Promisingly, there is a huge room for improvement in photovoltaic properties with rational fluorination or chlorination of the fused-DTBTz unit or the D moiety of the D-A polymers.

While a large number of terpolymers have been developed for polymer solar cells, very few studies have directly focused on the rational selection of the third component to balance the miscibility a...

A medium-band-gap donor–acceptor (D–A) polymer (PBDTS-DTBO) was designed and synthesized with alkoxyl-substituted benzo[c][1,2,5]oxadiazole (BO) as A unit and benzo[1,2-b:4,5-b']dithiophene (BDT) derivative (BDTTS) as D moiety. The resulting polymer not only possesses a high number-average molecular weight (Mn) of 53.0 kDa, but also exhibits a deep highest occupied molecular orbital (HOMO) energy level of −5.43 eV, which is in favor of a higher VOC of 0.88 V in the photovoltaic devices. Consequently, due to excellent phase separation and weak bimolecular recombination, the efficiency of the fullerene-based solar cells can reach 8.47% with a high current density (JSC) of 14.93 mA cm−2 and FF of 0.661, which is one of highest values for currently reported benzoxadiazole-based materials. In addition, considering the polymer also shows a medium optical bandgap of 1.75 eV, which can be well complementary with the classical non-fullerene acceptor ITIC. The best performance device exhibits a good efficiency of 6.45% in fullerene-free devices, which could be ascribed to the serious bimolecular recombination. This work revealed that alkoxyl-substituted benzoxadiazole could be a promising moiety to construct efficient light-harvesting polymer.

The instinct feature of π-bridges of donor-π-acceptor (D-π-A) conjugated polymers plays a critical role in tailoring the polymer basic properties as well as the photovoltaic performance. In this work, we designed two new D-π-A polymers PSeBDDIDT and PTzBDDIDT based on donor unit indacenodithiophene (IDT), acceptor unit benzo[1,2-c:4,5-c’]dithiophene-4,8-dione (BDD) with varying π-conjugated bridges of selenophene and thiazole units. Compared to the counterpart polymer PThBDDIDT with thiophene π-bridge, polymers PSeBDDIDT and PTzBDDIDT exhibited enhanced intermolecular interactions, expanded absorption range and better molecular planarity arising from the suppressed steric hindrance between the respective bridge and the adjacent BDD moiety. Conventional polymer solar cells were fabricated with PC71BM as the acceptor. The results witness a greatly improved efficiency for PSeBDDIDT based solar cell compared to PThBDDIDT based counterpart device (7.04%). As a result, the champion PCE of 8.65% was recorded with VOC of 0.899 V, JSC of 16.04 mA cm−2 and FF of 0.60. It is worth highlighting that this is the highest efficiency among all IDT-based polymeric donors reported till now. As a contrast, the devices fabricated from PTzBDDIDT demonstrated a low efficiency of 2.75%, with increased VOC of 0.968 V, JSC of 8.12 mA cm−2 and FF of 0.35. The inferior photocurrent and fill factor of PTzBDDIDT based device was in accord with the poor exciton dissociation probability (38%) and low hole and electron charge transport inside the polymer solar cell. In conclusion, this work demonstrates a state of the art IDT-based polymeric donor with selenophene π-bridge and the importance of rational regulation of π-bridges on polymer properties and photovoltaic efficiency of polymer solar cells.

In this work, one new middle bandgap (1.63 eV) copolymer, PBDDTT-3TC, was prepared by copolymerization of benzodithiophenedione (BDD) and symmetric terthiophene (3TC) with two carboxylate substituents. Devices based on PBDDTT-3TC : ITIC (1.0 : 1.0, wt/wt) exhibit an electron mobility of 1.79 × 10−4 cm2 V−1 s−1 and a hole mobility of 1.77 × 10−4 cm2 V−1 s−1, indicating a more balanced charge transport (μh/μe = 0.99). The opaque PSC exhibits a high Voc of 1.00 V and a PCE of 6.92% without any additive or thermal-annealing treatment and with 100 nm Ag as the cathode, and the as-cast semitransparent PSC with equal treatment and 15 nm Ag as the cathode shows a high Voc of 0.99 V and a PCE of 6.15% with an average transmittance of 23.83% and an average visible transmittance of 19.16%. This work suggests the potential of PBDDTT-3TC:ITIC as an active layer for fabricating highly efficient semitransparent PSCs.

To clearly show how important the impact of side chains on organic solar cells (OSCs) is, we designed three acceptors IDIC-CxPh (x = 4, 5, or 6) via subtle side-chain regulation. Despite this small change, significant distinctions were detected. IDIC-C4Ph devices achieve an optimal efficiency of 13.94% under thermal annealing, but thermal-assistant solvent-vapor annealing hugely suppresses the efficiencies to 10%. However, the C6Ph side chain endows extremely disordered stacking orientations, generating moderate efficiencies of ~12.50%. Excitingly, the IDIC-C5Ph affords an unexpected two-channel π-π charge transport (TCCT) property, boosting the fill factor (FF) by up to 80.02% and efficiency to 14.56%, ranking the best among five-ring fused-ladder-type acceptors. Impressively, the special TCCT behavior of IDIC-C5Ph enables 470 nm thick-film OSC with a high FF of up to 70.12% and efficiency of 13.01%, demonstrating the great promise in fabricating large-scale OSCs., Graphical abstract, Public summary • OSCs are a promising technology to transform the solar energy to electricity • This article reports an efficient TCCT photovoltaic material through subtle side-chain modification • The TCCT property enables 13% efficiency with FF reaching 70% in 470 nm thick-film photovoltaics

With proven gas potential, the gas charging and accumulation mechanisms for the Upper Paleozoic tight gas reservoir in the Longdong District of the Ordos Basin remain controversial. Pore structure is the most direct and critical factor that affects gas charging and accumulation in the reservoir. However, the pore structure characterization of tight sandstone is far more difficult than that for conventional reservoir rocks due to significant heterogeneity. The present work aims to introduce a new quantitative method for pore structure characterization that integrates multi-fractal distribution analysis, an effective and profitable method for quantitative heterogeneity analysis, and high-pressure mercury intrusion porosimetry (HPMIP). Twenty-one samples from targeted tight formations with different gas-bearing status were obtained for analysis. The results show that the best formations for gas charging and accumulation in the Upper Paleozoic tight sandstone formations in the Longdong District are the formations with more large pores, more homogeneous small pores, and well-developed micro-fractures. The existence of micro-fractures is the key factor that affects gas charging and accumulation. Tight sandstone samples were categorized into three types in accordance with the HPMIP curve configuration. Due to the high heterogeneity of pore structures, analyses based solely on HPMIP curve configuration has its shortcomings, which can be compensated by multi-fractal distribution analysis. The multi-fractal distribution of target tight formations could be interpreted as two linear segments, representing large pores and small pores. The separating points of the two segments vary from 0.1 μm to 0.5 μm in different samples due to different pore structures. Large pores are not ideal fractals in gas-bearing formations due to the existence of micro-fractures, whereas they are fractals in dry formations where micro-fractures are not developed. Small pores are all ideal fractals, with the highest heterogeneity in type γ samples and the lowest heterogeneity in type α samples. A conclusion was made in this work: if the slope of segment one in the multi-fractal distribution of mercury saturation (SHg) versus capillary pressure (PC) is larger than 1, this measure could be accepted as an empirical indicator for the existence of micro-fractures.

Multichromophoric oligomers offer a versatile platform for nanoparticle multicolor fluorescent modulation. A donor–acceptor–donor (D–A–D) type oligomer (DDBTD), with blue emitting antenna and red emitting core, is chosen to assemble into fluorescent colloidal nanoparticles (FCNs) using a nanoprecipitation method. By modulating the DDBTD concentrations in good solvent, the DDBTD nanoparticles with average diameters ranging from sub-10 to 300 nm are obtained by the nanoprecipitation process in aqueous solution. Interestingly, multicolor photoluminescence (PL) can be realized from bright blue (∼440 nm) to rose red (∼630 nm) based on FCNs size control. The size-dependent PL originates from the aggregation-enhanced fluorescence resonance energy transfer (FRET) from diphenyl-aminofluorenyl antenna unit (blue emitter) to benzothiadiazole-based core (red emitter). Furthermore, the lifetime measurement of the FCNs in excited state shows a size-dependent behavior, which confirms that the size-dependent multicolor P...

Shale-hosted hydrocarbons is regarded as an important unconventional resource around the world. So far, huge emphasis has been put on the contribution of organic pores to self-source and self-reservoir hydrocarbon systems. This study systemically reveals the contribution of organic pores to hydrocarbon potential in the Duvernay Shale through restoring thermal maturity evolution, modeling hydrocarbon generation and expulsion in the Duvernay Formation, analyzing absorption capacity variation with TOC and modeled pore pressure, determining free-gas storage capacity with calculated organic porosity and correction of adsorbed gas, and calculating in-place shale oil and gas volumes with volumetric method. The Duvernay Shale reached “oil window” and “gas window” about 70–80 Ma and 50 Ma ago, respectively. Significant hydrocarbon generation (20% TR) began and terminated (95% TR) at Ro of 0.65% and 1.85%, respectively. Gas generation rates increased dramatically from Ro of 1.1%, while the instantaneous HC1-4 expulsion reached peak at Ro of 1.66%, the difference between which indicates considerable retained gas resource in Duvernay Shale. The gas storage capacity, including absorption capacity and free gas capacity, varies significantly in the Duvernay Shale, specifically, the former rangs from 8 to 30scf/ton, and the latter from 40 to 140scf/ton. The estimated median value of total in-place natural gas (GIP) and in-place oil resource (OIP) in organic pores of Duvernay shale are 404.8 TCF and 81420 MMbbl, respectively. Thus, the organic porosity is one of the keys to make the Duvernay Shale a successful play.

Extending π-conjugation in the benzodithiophene (BDT) side chains has been proven useful to improve the efficiencies of the BDT-based polymer solar cells (PSCs). Herein, combined with a symmetry-breaking strategy of a BDT unit, we further designed a new asymmetric 1D–2D (one dimensional–two dimensional) monomer asy-BDTBP with an alkoxyl group as the 1D part and a π-extending alkoxybiphenyl as the 2D substituted group. Medium band-gap donor–acceptor (D–A) conjugated polymer P1 was synthesized with asy-BDTBP and 4,7-di(4-(2-ethylhexyl)-2-thienyl)-5,6-difluoro-2,1,3-benzothiadiazole (DTffBT) as the donor and acceptor unit, respectively. Encouragingly, P1 blended with PC71BM exhibited an obviously enhanced power conversion efficiency (PCE) compared to the reported symmetric analogue PBDTBP–DTffBT (6.70%). The PCE increased to 8.45% with an open-circuit voltage (VOC) of 0.838 V, a short-circuit current density (JSC) of 14.35 mA cm−2 and a fill factor (FF) of 70.27%. However, P1 coupled with a classical non-fullerene acceptor ITIC revealed a relatively poor efficiency of 6.35% due to the bad complementarity of absorption spectra. To match the absorption of ITIC, a wide band-gap D–A polymer P2 was further designed with a weak electron-withdrawing group benzo[1,2-c:4,5-c′]dithiophene-4,8-dione (BDD) instead of DTffBT as the acceptor unit. As a result, P2 possessed a complementary absorption spectrum with ITIC, and the resulting devices presented an excellent photovoltaic performance. The optimal efficiency boosted to 10.04% with VOC of 0.873 V, JSC of 17.60 mA cm−2 and FF of 65.37%. This work demonstrates the great potential of asymmetric BDTs for high efficient PSCs and the importance of the rational design of polymers for different types of PSCs.

In this work, we reported efficient polymer solar cells with balanced hole/electron mobilities tuned by the acceptor content in bulk heterojunction blend films. The photovoltaic cells were fabricated with two new wide band-gap D-A polymers PBDDIDT and PBDDIDTT as the donor material. The molecular conformations of new polymers are carefully evaluated by theoretical calculations. The results of photovoltaic studies show that two devices reach their optimal conditions with rich PC 71 BM content up to 80% in blend films, which is uncommon with most of reported PSCs. The as-cast devices based on PBDDIDT and PBDDIDTT reveal good photovoltaic performance with PCE of 7.04% and 6.40%, respectively. The influence of PC 71 BM content on photovoltaic properties is further detailed studied by photoluminescence emission spectra, charge mobilities and heterojunction morphology. The results exhibit that more efficient charge transport between donor and acceptor occurs in rich PC 71 BM blend films. Meanwhile, the hole and electron mobilities are simultaneously enhanced and afford a good balance in rich PC 71 BM blend films (D/A, 1:4) which is critical for the improvement of current density and fill factors.

The recent evolution of non-fullerene acceptors yields brilliant progress for organic solar cells (OSCs). However, high-performance copolymer donors with simple chemical structures for new acceptors are a few. In this work, a series of donors based on BDT are developed with ester-substituted trithiophene as a repeating acceptor unit. Copolymerized polymers exhibit slightly red-shifted absorption and down-shifted the highest occupied molecular orbital (HOMO) as the side chains turning from alkyl (3TCO-R) and oxyalkyl (3TCO-OR) to thienyl (3TCO-Th) and chlorine-substituted thienyl (3TCO-Th-Cl), respectively. As a result, the corresponding power conversion efficiency (PCE) of 3TCO-Th-Cl based devices shows the most excellent performance (PCE = 7.70%) especially in open-circuit voltage (VOC = 1 V) when blending with ITIC and its PCE makes a breakthrough with Y6 (PCE = 10.30%). Moreover, the fabricated semitransparent OSCs exhibit a rational PCE of 8.16% with average visible transparency of 16.40%.

In this paper, we reported a crystalline p-type medium-bandgap conjugated D–A polymer asy-PBDBTN based on a symmetry-breaking-modified BDT moiety to combine the advantages of both one-dimension (1D) and two-dimension (2D) symmetric BDTs. Polymer asy-PBDBTN is a highly efficient light-harvesting donor material. Single BHJ PSCs exhibit PCE of 8.88% with PC71BM as acceptor. Also, PCE values of 10.50% are achieved with the use of ITIC as an acceptor to couple asy-PBDBTN with VOC of 0.942 V, JSC of 16.81 mA cm–2, and FF of 0.663. It is worth noting that lower energy loss is obtained in fullerene-free-based PSCs, which is essential to overcome the trade-off between VOC and JSC and boost these two parameters simultaneously for high photovoltaic performance. The combination process of additive and thermal annealing is critical to enhance and retain the π–π stacking behavior of donor and fullerene-free acceptor; as a result, the trap-assisted recombination was greatly suppressed. This work demonstrates a great pro...

In this work, 2-(3-ethyl-4-oxothiazolidin-2-ylidene)malononitrile is connected on the β position of thiophene, and this monomer is copolymerized with indacenodithiophene (IDT) to build one novel photovoltaic polymer (PIDTPCR). The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) level of the polymer is −5.26 eV and −3.45 eV, respectively. Compared with reference polymer without rhodanine side chain, PIDTPCR polymer shows low band gap and low energy level which contribute to the Jsc and Voc of the PSCs devices. The best performance parameters of the solar cells devices are Voc (0.91 V), Jsc (10.1 mA/cm2), FF (52.4%) and PCE (5.18%).

In this paper, to study the two-dimensional (2D) conjugated side chain effect on the polymer donor for the non-fullerene polymer solar cells (NFPSCs), the thiophenothiophene (TT) side-chained benzodithiophene (BDT) and bithiophene copolymer (PBDTDT-TT) has been prepared by the Stille coupling reaction and compared with the copolymer (PBDTDT-O) with an alkoxy side group and the same polymer backbone. The 2D conjugated polymer PBDTDT-TT exhibits better thermal stability and wider and red-shifted ultraviolet–visible absorption spectra. These two copolymers were used as the donor materials blended with a new non-fullerene receptor ITM, successfully fabricating the positive devices with an ITO/PEDOT:PSS/polymer:ITM/PFN-Br/Al structure. Compared with the PBDTDT-O:ITM blend film, the PBDTDT-TT:ITM blend film shows a lower LUMO energy level, a narrower optical band gap, and a higher electron and hole mobility in the devices. The best power conversion efficiency (PCE) is 8.43% for the PBDTDT-TT polymer, while the ...

Here we design and synthesize one novel fluorene side-chained benzodithiophene (BDT) monomer for polymer solar cells (PSCs) donor. By copolymerizing this monomer with 4,7-di(thiophen-2-yl)-2,1,3-benzothiadiazole (DTBT) or 4,7-di(4-(2-ethylhexyl)-2-thienyl)-5,6-difluoro-2,1,3-benzothiadiazole (DTffBT), two donor–acceptor (D–A) conjugated polymers PFBDT–DTBT and PFBDT–DTffBT are prepared. PSCs are prepared with these polymers as donor and PC71BM as acceptor. The maximum power conversion efficiency (PCE) of the two polymers PFBDT–DTBT and PFBDT–DTffBT based PSCs is 7.13% (VOC = 0.90 V, JSC = 13.26 mA cm–2, and FF = 0.598) and 7.33% (VOC = 0.96 V, JSC = 13.24 mA cm–2, and FF = 0.577). The UV–vis absorption and electrochemical cyclic voltammetry test results show that F atoms in DTffBT unit present an obvious influence on intermolecular effect and molecular energy levels of polymers. Furthermore, the energy loss of two PSCs devices in this work is confirmed to be 0.78 and 0.71 eV, lower than most results based...

The micro-structure ordering of the π–conjugated polymer film self-assembling from solution governs its electrical characteristics and performances for organic electronics. The side chains appended on the conjugated backbone could impact the self-assembling characteristics of the polymer, which show us how to design novel substituents to optimize the polymer arrangement and packing in its solid state. Here, cyclic alkyl chains are proven to be excellent ones for designing of narrow bandgap polymers, the design feature of which with preferential conformations can promote the polymer self-assembly and result in higher degree of lamellar order as well as tighter lamellar packing in the active layer, comparing with linear alkyl chains. The linear ones have poorer ordering in the polymer:fullerene blends as well as in the single crystals of the monomers. The well-organized polymer micro-structures facilitate polymer:fullerene phase separation together with balanced hole/electron transporting, and ultimately, improve the power conversion efficiency impressively compared to linear chains.

Four dithienoindaceno[1,2-b:5,6-b′]dithiophene (DT-IDT) based small molecules IT-O1, IT-O2, IT-O3 and IT-O4 with increasing alkoxyl chain length from methoxy to butoxy on the terminal-groups were synthesized to investigate the end-group side-chain effects on these acceptor–donor–acceptor-type small molecule electron acceptors. The optical absorption and energy levels of the four molecules, blend morphologies, carrier mobilities, and photovoltaic performances of the devices blended with the polymer PBDB-T are systematically investigated. Interestingly, both the solubility and electron mobility are enhanced for these materials with decrease in side chain length, which lead to ideal morphologies and balanced charge transport. Hence, increased Jsc and FF, and thus distinctly higher PCEs of 11.6% were obtained from the PBDB-T:IT-O1-based devices.

Two novel copolymer donors based on one-dimensional (1D)–two-dimensional (2D) asymmetrical benzodithiophene (BDT) units (BDTPH-H and BDTPH-OR) and 2,3-diphenyl-5,8-di(thiophen-2-yl)quinoxaline (DTQx) were synthesized and compared with one-dimensional or two-dimensional symmetric BDT unit based photovoltaic polymers. Both asymmetrical polymers exhibited promising photovoltaic performance compared with 1D and 2D symmetric BDT polymers. The power conversion efficiency (PCE) of PBDTPH-DTQx based polymer solar cells is 5.6%, with balanced VOC = 0.7 V, JSC = 11.89 mA cm−2 and FF = 67.3%, which is almost the highest PCE compared with similar BDT unit and fluorine-free substituted DTQx based polymer. What is more, PBDTPH-DTQx shows better performance than PBDTPHO-DTQx due to the single phenyl making DTQx more planar and with better π–π stacking than alkoxy phenyl. These findings demonstrate that the 1D–2D asymmetrical BDT units are also applicable to poor planarity fluorine-free substituted quinoxaline acceptor system.

To study which strategy (extending side chain π-conjugation with single-bonded or fused aromatic rings) is more effective in improving the photovoltaic properties of benzodithiophene (BDT)-based polymers, naphthyl (NP) and biphenyl (BP) units were introduced to the BDT core as conjugated side chains. Two polymers PBDTNP-DTBO and PBDTBP-DTBO based on NP or BP-substituted BDT and 5,6-bis(octyloxy)-4,7-di(thiophen-2-yl)benzo[c][1,2,5]oxadiazole (DTBO) were designed. These two polymers only exhibited small differences in the chemical structure, but great differences in photovoltaic performance. PBDTNP-DTBO showed a high power conversion efficiency (PCE) of 8.79%, with an open-circuit voltage (Voc) of 0.82 V, a short-circuit current density (Jsc) of 14.34 mA cm−2, and a fill factor (FF) of 74.73%, while PBDTBP-DTBO only showed a maximum PCE of 6.69%, with a Voc of 0.75 V, a Jsc of 13.55 mA cm−2, and a FF of 65.86%. Hence, extending the side chain π-conjugation system of a BDT-based polymer with naphthyl is a more effective method to enhance the photovoltaic properties.

In this work, α- and β-position naphthalene substituents as side chains on asymmetric BDT were used as donor building blocks to build wide bandgap (WBG) donor materials (PαNBDT-T1 and PβNBDT-T1) with fluorinated benzotriazole (T1) as the acceptor unit. The two co-polymers were used to build polymer solar cells (PSCs) with PC71BM or ITIC acceptor material. In ITIC acceptor material based devices, the PαNBDT-T1 co-polymer with a larger dihedral angle between main backbone and naphthalene ring achieved a higher power conversion efficiency (PCE) of 9.60% with improved short-circuit current density (JSC) and fill factor (FF) compared with PβNBDT-T1, which was ascribed to the excellent morphology of the blended film. The open circuit voltage (VOC) was also maintained at a decent level upon introducing these naphthalene rings due to their high ionization potential and low electron density. Interestingly, for PC71BM based devices, the two polymers show a reverse situation compared with an ITIC system. The PβNBDT-T1 with a small dihedral angle between the main backbone and naphthalene rings shows a slightly higher performance than PαNBDT-T1. However, in the PC71BM system, both polymers did not exhibit ideal optical performance due to their unmatched absorption spectrum. These phenomena indicate that the asymmetric BDTs have great potential towards achieving high optical performance with non-fullerene acceptor materials.

A series of conjugated polymers based on PFS derivatives with π-conjugated 5-(9H-fluoren-2-yl)-2,2′-bithiophene (fluorene-alt-bithiophene) backbones, namely PFS-3C, PFS-4C and PFS-6C, were synthesized for their use as the anode interfacial layers (AILs) in the efficient fullerene-free polymer solar cells (PSCs). Alkyl sulfonate pendants with different lengths of alkyl side chains were introduced in the three polymers in order to investigate the effect of the alkyl chain length on the anode modification. The obtained three polymers exhibited similar absorption bands and energy levels, indicating that changing the length of the alkyl side chains did not affect the optoelectronic properties of the conjugated polymers. Based on the PBDB-T:ITIC active layer, we fabricated the fullerene-free PSCs using the three polymers as the AILs. The superior performance of the fullerene-free PSC device was achieved when PFS-4C was used as the AIL, showing a power conversion efficiency (PCE) of 10.54%. The high performance of the PFS-4C-modified device could be ascribed to the high transmittance, suitable work-function (WF) and smooth surface of PFS-4C. To the best of our knowledge, the PCE obtained in the PFS-4C-modified device is among the highest PCE values in the fullerene-free PSCs at present. These results demonstrate that the PFS derivatives are promising candidates in serving as the AIL materials for high-performance fullerene-free PSCs.

To protect the lacquer plates from the Nanhai No. 1 shipwreck from being corroded by microorganisms, a series of studies were conducted on the four water-stored samples. The water samples were collected from the vessel where the lacquerware was stored in June and December 2017. In our study, high-throughput sequencing was conducted to reveal predominant bacterial communities. Then, three different media were used to isolate the dominant bacteria, and the 16S rRNA genes were sequenced. Next, we tested the degradation activity of lignin and cellulose by the isolated bacterial strains. After being cultured on a medium containing carboxylmethylcellulose (CMC), almost all the isolated strains (except Microbacterium sp. NK-NH4, Ochrobactrum sp. NK-NH9, and Bacillus megaterium NK-NH10) showed the capacity for cellulose degradation. In addition, the lignin peroxidase (Lip) and laccase activity of the strains were shown by culturing the strains on one medium with azure and on another medium with Remazol brilliant blue. The results indicated that the Lip activity of all the strains was low, whereas the laccase activity of Microbacterium sp. NK-NH4, Bacillus tequilensis NK-NH5, Bacillus subtilis NK-NH6, Bacillus megaterium NK-NH10, and Bacillus velezensis NK-NH11 was relatively high. Finally, we tested the bacteriostatic efficacy of four biocides&mdash, Preventol&reg, D7, BIT 20N, P91, and Euxyl&reg, K100. We found that most strains were sensitive to D7 and 20N, while K100 had almost no impact.

Designing and synthesizing new organic photovoltaic materials is an inexhaustible driving force for the development of polymer solar cells (PSCs). For an excellent molecular structure with a certain conjugated skeleton, studying its analogues is of considerable significance for fully exploiting its photovoltaic potential. In this work, naphtho[2,3-c]thiophene-4,9-dione (NTD), an analogue of benzo [1,2-c:4,5-c’]dithiophene-4,8-dione (BDD), was designed and synthesized. Based on this building block, alkoxy side chains and alkylthio side chains were grafted on NTD to build NTD-O and NTD-S unit respectively, and then two new D-A conjugated donor polymers, PBNO and PBNS, were synthesized with NTD-O and NTD-S units as acceptor units and asymmetric benzodithiophene unit (asy-BDTBP) as donor units. Later, the photoelectric properties of these two materials in fullerene PSCs were studied. Compared with BDD based benzodithiophene copolymer (asy-BDTBP-BDD), PBNO and PBNS show similar LUMO energy levels, −3.59 eV and −3.63 eV, respectively, PBNO and PBNS show higher HOMO energy levels, which are −5.25 eV and −5.37 eV, respectively. PBNO blended with fullerene acceptor PC71BM exhibited similar power conversion efficiency (PCE) compared to the copolymer asy-BDTBP-BDD (4.64%). The PCE is 4.71% with short-circuit current density (JSC) of 9.85 mA cm−2, open-circuit voltage (VOC) of 0.784 V and fill factor (FF) of 60.98%. Encouragingly, PBNS presented an obviously enhanced PCE in PC71BM system PSCs, and PCE boosted to 7.58% (JSC, 12.40 mA cm−2; VOC, 0.865 V; FF, 70.83%). This work shows that analogues of excellent molecules have huge photovoltaic potential, and that side-chain modification has a significant impact on improving the photovoltaic performance of PSCs.

In this work, four wide-bandgap (WBG) conjugated polymers based on asymmetrical building block thieno [2,3f]benzofuran (TBF) and fluorobenzotriazole (BZ), are synthesized and applied as donor materials in polymer solar cells (PSCs). The effect of conjugated side chains (alkylthiothiophenyl, alkylthiophenyl, alkylphenyl and fluoroalkoxyphenyl) on the optical absorption, electrochemical and photovoltaic properties are investigated in detail. These polymers exhibit similar properties, strong absorption from 300 to 650 nm with wide bandgaps ranging from 1.87 to 1.96 eV, excellent thermal stability, the high and balanced carrier mobility. Notably, the open-circuit voltages (VOC) of PTSDO-BZ increases by 0.16 V compared with PTDO-BZ. Similarly, larger VOC changes have also occurred in PPEH-BZ and PPFOEH-BZ comparation. The enhanced VOC can be ascribed to the low-lying highest occupied molecular orbital (HOMO) energy level by incorporating sulfur and fluorine substituents on the conjugated side chains. The as-cast devices of PTSDO-BZ:ITIC exhibit the highest power conversion efficiency (PCE) of 8.66%, with a VOC of 0.88 V, a short-circuit current density (JSC) of 15.06 mA cm−2, and a fill factor (FF) of 65.12%. The results indicate that the modification of the side chains of the TBF unit can effectively lower the HOMO energy levels and thereby obtaining high VOC.

Herein, a series of random donor copolymers were reported, by incorporating different contents of electron-rich 4,8-bis(9,9-bis(2-ethylhexyl)-9H-fluoren-2-yl)benzo[1,2-b:4,5-b']dithiophene (BDTF) units into PBDB-T (poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione))]) polymer to fine-tune the highest occupied molecular orbital (HOMO) energy level. As we expected, downshifted HOMO of corresponding copolymers was observed with increased the ratios of BDTF unit on PBDB-T polymer, causing by the synergy of weak electron-donating ability of the fluorene side chains and the enhanced dihedral angles. Notably, compared with PBDB-T, the HOMO energy level of P91 containing 10% BDTF was shifted down by 0.07 eV. Among them, the devices based on P55:ITIC reached a high open-circuit voltage (VOC) of 1.00 V with incorporation of 50% of BDTF units. The result indicated that the BDTF unit, as an excellent building unit in donor materials, could play a crucial role to realize high-VOC polymer solar cells.

In this work, one novel asymmetric non-fullerene acceptor ITIC-3T was designed and synthesized. ITIC-3T molecule shows 1.58 eV Eg, with −3.95 eV LUMO level. Utilizing P3 (one asymmetric 2D conjugated benzodithiophene polymer) as donor material, bulk heterojunction solar cells were fabricated. The optimal device yields a PCE of 6.47% with a VOC of 0.64 V, a FF of 55.5% and a high JSC of 18.18 mA cm−2, which may be attributed to the complementary optical absorption of active blend (P3 and ITIC-3T). In general, this work demonstrates that asymmetric polymer donor and non-fullerene acceptor active layer blend is potential for fabricating efficient photovoltaic cells.

Monolithic Al 2 O 3 -SiO 2 -TiO 2 with multiscale porous structures has been prepared via a sol-gel process accompanied by phase separation. Poly(ethylene oxide) (PEO) is used to induce the phase separation and formamide (FA) to control the gelation of ternary system. The dried gel is amorphous. After heat treatment at 1050 °C, the gel transforms into the phase Al 4 Ti 2 SiO 12 . The interconnected macropores are well maintained and the meso-/micropores are disappeared. The homogeneous dispersion of Al, Si and Ti in the skeleton indicates that sol-gel technique could provide a very feasible way for the preparation of hierarchical monolithic composite materials.

It is known that fluorination on π-conjugated donor-acceptor (D-A) polymers can significantly affect the optoelectronic properties and fluorination on A moiety has been well established for design of efficient photovoltaic materials. For example, polymers based on 4,7-dithienyl-5,6-difluorobenzothiadiazole (DTffBT) have been intensively investigated and exhibited excellent performance, but the corresponding DTBT-based polymers without fluorine often display an unfavorable efficiency. With the purpose of improving photovoltaic efficiency of DTBT-based D-A polymers, we design three polymers PDTBT-TxfBT (x = 0, 1, 2) with fluorination on D moiety (TxfBT) and systematically investigate fluorination on the photophysical/electrochemical and photovoltaic properties. The results show that polymer solar cells (PSCs) based on PDTBT-TBT exhibit moderate power conversion efficiency (PCE) of 5.84%. However, the bis-fluorination on TffBT moiety (PDTBT-TffBT) can greatly enhance the molecular planarity and intermolecular interaction, improve the charge transport and heterojunction morphology, and further suppress the charge recombination losses. PSCs based on PDTBT-TffBT demonstrate obviously improved photovoltaic efficiency with the best PCE up to 7.53% without any processing additives, which ranks among the top DTBT-based PSCs. However, it should be noted that unsymmetrical fluorination on TfBT moiety (PDTBT-TfBT) impairs the regularity of polymer backbone and intermolecular interaction, increases the recombination losses, and seriously reduces the short-circuit current density and efficiency (5.44%). The results exhibit that fluorination on D moiety is a helpful strategy for design high-performance photovoltaic materials and the regularity of fluorination is crucial to improving efficiencies.

In this paper, a novel donor based on alkylthiophenyl side-chained benzodithiophene (BDT) (M1) was first designed and synthesized to construct a series of conjugated polymers (P1, P2, P3) used in polymer solar cells (PSCs). P1, P2, and P3 were prepared by copolymerizing M1 with 4,7-di(4-(2-ethylhexyl)-2-thienyl)-2,1,3-benzothiadiazole (DTBT), quinoxaline, and diketopyrrolopyrrole (DPP), respectively. The optical electrochemical and photovoltaic properties of these polymers were investigated. Alkylthiophenyl substitution on the BDT building block is favorable for the low-lying highest occupied orbital (HOMO) level of polymers. The HOMO of these copolymers is clearly lowered to −5.49 eV, −5.34 eV, and −5.50 eV, respectively. Compared with reference polymers, our polymers show lowered HOMO energy levels (by 0.14 eV at least). This is very helpful to enhance the open-circuit voltage (Voc) of the devices. Further, P2:PC61BM exhibited an optimized power conversion efficiency (PCE) of 4.28 %, which is clearly higher than that of P1 (1.48 %) and P3 (1.9 %).

Determination of total organic carbon (TOC) is essential in unconventional shale resource play evaluation. Indirect method, such as petrophysical approach, can provide a fast, convenient and cost efffective means for TOC estimation from well logs. Among the publically available approaches, the ΔlogR method is a popular one in conventional source rock evaluation and has been applied to unconventional resource play evaluation by many practitioners. Careful examination of the method finds that improvements can be made for a better TOC estimation with relaxed limitations. This study proposes the following revisions on the original ΔlogR method: 1) allowing estimation of petrophysical parameters from the targeted source rock rather an assumed linear approximation, 2) using additional logs to improve TOC prediction, and 3) replacing LOM (level of organic metamorphism unit) with a more commonly used thermal indicator Tmax for convenience. Depending on data or preference, the choice of using different porosity logs (density versus sonic) and parameter estimation methods (cross-plot method versus data-driven approaches) makes the revised method flexible for application. We present the revisions along with application examples from the Devonian Duvernay Shale in the Western Canada Sedimentary Basin to demonstrate the application of the improved ΔlogR method in shale gas evaluation. Comparison of the results from the revised method and the original one reveals that the revised models provide better and unbiased estimates of TOC with a higher correlation coefficient and bell-shaped residues centered at zero.

A diketopyrrolopyrrole (DPP)-based π-conjugated polymer is a very promising low band gap electron donor material for polymer solar cells. We have incorporated alkyl groups into the 4-position of the thiophene rings connected to the DPP fragment, which is proven to be beneficial for improving the open-circuit voltage (VOC) and short-circuit current density (JSC). Two DPP-based polymers are synthesized with benzo[1,2-b:4,5-b′]dithiophene (BDT) as the electron-donating segment. Both the polymers show good solubility, slightly wide optical band gaps and deep HOMO energy levels when incorporating the alkyl groups. Heterojunction solar cells are fabricated with polymer:PC71BM as the active layer. VOC and JSC are simultaneously enhanced compared to the device performance of traditional DPP-BDT alternating polymers. A power conversion efficiency (PCE) of 8.11% was obtained, which indicates that rational utilization of backbone torsion is a promising strategy to improve the photovoltaic performance.

A novel monomer alkoxybiphenyl-substituted benzodithiophene (BDTBP) was synthesized and used as the donor to construct a donor–acceptor copolymer PBDTBP–DTffBT with 4,7-di(4-(2-ethylhexyl)-2-thienyl)-5,6-difluoro-2,1,3-benzothiadiazole (DTffBT) as the acceptor unit. Compared with the corresponding polymer PBDTP–DTffBT based on alkoxyphenyl-substituted BDT, PBDTBP–DTffBT exhibits a red-shifted UV-vis absorption spectra due to its extended π-conjugation structure. The maximum power conversion efficiency (PCE) of PBDTBP–DTffBT based polymer solar cells (PSCs) is 6.70% with Voc = 0.85 V, Jsc = 12.72 mA cm−2 and FF = 62.14%, and the hole mobility is 3.45 × 10−4 cm2 V−1 s−1 while the maximum PCE of PSCs based on PBDTP–DTffBT is only 4.91% and the hole mobility is 1.70 × 10−5 cm2 V−1 s−1. These findings demonstrate that BDTBP unit is a promising building block for constructing a copolymer with high hole mobility, and extending the π-conjugation length on the alkoxyphenyl-substituted BDT is helpful to improve the photovoltaic properties.

Two wide band gap (WBG) polymers based on thiophene-thiazolothiazole (TTz) units, PBT-TTz and PBT-S-TTz, were synthesized. Both polymers showed absorption onsets at 635 nm in solid films. Although PBT-TTz and PBT-S-TTz are WBG materials with relatively narrow absorption spectra, they have great potential for constructing high-performance polymer solar cells (PSCs). By replacing the alkyl side chain of PBT-TTz with an alkylthiol side chain, the HOMO level of PBT-S-TTz was lowered to −5.45 eV. A PCE of 7.92% was then obtained in a single-junction PSC device based on a PBT-S-TTz:PC71BM active layer. Moreover, high-performance fullerene-free PSCs were fabricated using these polymers and a high PCE of 8.22% was achieved. This work demonstrates that TTz-based polymers PBT-TTz and PBT-S-TTz are promising candidates as efficient WBG polymers for constructing high-performance PSC devices.

A new monomer dithieno-[3′,2′:3,4;2′′,3′′:5,6]benzo[1,2-c]xadiazole (fDTBO) is first used as an electron-deficient acceptor to build D–A copolymers in a photovoltaic field. Two polymers PBDTT-fDTBO and PBDTO-fDTBO consist of fDTBO with thienyl-substituted-benzodithiophene (BDTT) or alkoxy-substituted benzodithiophene (BDTO). Both polymers show a deep HOMO around −5.5 eV with a wide band gap of over 1.9 eV. The polymer solar cells (PSCs) based on two polymers both show over 1 V high open circuit voltage (Voc) independent of polymer/PCBM ratios and solvent additives content in the PSCs active layer. The power conversion efficiency (PCE) based on PBDTT-fDTBO devices is 4.5% for single junction PSCs, and these polymers can be applied in tandem PSCs due to their wide band gap (up to 1.99 eV). This work demonstrates that the fDTBO unit is a promising building block to design wide band gap photovoltaic polymers with high Voc.

The conformational change of the polymer backbone has an obvious influence on the blended film morphology and the photovoltaic properties. A planar polymer backbone can provide strong intermolecular interaction, but excessive self-aggregation usually disadvantages a favorable film morphology. Here, a dithienothiophene (DTT) unit and a terthiophene (T3) unit were introduced to construct a pair of new conjugated polymers, PDTT-DTBT and PT3-DTBT, respectively, to investigate the correlation between the conformation of the polymer backbone and the photovoltaic properties. The highly planar structure of the DTT unit made PDTT-DTBT exhibit a stronger molecular aggregation than PT3-DTBT. Compared to the DTT unit, the T3 unit changed the molecular structure from fused thiophenes to linked ones, which relaxed the rigidity of the polymer backbone and reduced the degree of polymer self-aggregation, and a more suitable blended film morphology was formed. Due to the weaker electron-donating ability of the DTT unit, PDTT-DTBT/PC71BM-based devices showed a higher open circuit voltage (Voc) of 0.75 V, and a power conversion efficiency (PCE) of 8.01% was obtained with a short-circuit current (Jsc) of 14.85 mA cm−2 and a filled factor (FF) of 71.62%. This PCE value was slightly higher than for PT3-DTBT/PC71BM-based devices, which exhibited a PCE of 7.68% (along with a Voc of 0.66 V, a Jsc of 16.62 mA cm−2 and a FF of 69.69%).

In order to investigate the effect of an (E)-1,2-di(thiophen-2-yl)ethene (TVT) unit on the hole mobility and photovoltaic properties of dithienyl-difluorobenzothiadiazole (DTBT) based polymers, two conjugated polymers PDT-DTBT-DT (thiophene backboned) and PTVT-DTBT-DT (TVT backboned) were synthesized. Compared to PDT-DTBT-DT, the backbone conformation of PTVT-DTBT-DT could be well modulated by the TVT unit, leading to an extended conjugation length and strengthened intermolecular interaction. Interestingly, it's found that the ultraviolet-visible (UV-vis) absorption peaks of the PTVT-DTBT-DT film was blue-shifted compared to that of the solution. The organic field-effect transistor (OFETs) characterization showed that PTVT-DTBT-DT possessed a high hole mobility of 0.12 cm2 V−1 s−1, which was higher than that of the counterpart PDT-DTBT-DT (0.04 cm2 V−1 s−1). Through simplified device optimization without any additives and annealing treatment, a power conversion efficiency (PCE) of 7.86% was achieved for PTVT-DTBT-DT with a short-circuit current density (Jsc) of 16.33 mA cm−2 and a fill factor (FF) of 68.92%, which is higher the PCE of 7.29% of PDT-DTBT-DT with a Jsc of 15.60 mA cm−2 and a FF of 66.62%. The PCE of 7.86% is among the highest PCEs reported for devices fabricated without any additives and thermal annealing treatment. The results revealed that PTVT-DTBT-DT as an ideal conjugated polymer could provide a greater possibility for the commercial application of PSCs, especially in terms of low cost and manufacturing convenience.

Thiadiazolo[3,4-c]pyridine (PT) has great potential in the construction of high-performance narrow bandgap (NBG) photovoltaic polymers. But to date the best power conversion efficiencies (PCEs) for PT-containing polymers are only around 6%. Herein, we report two PT-containing NBG polymers PDTPT-2T and PDTPT-2TF based on 2,2′-bithiophene (2T) and 3,3′-difluoro-2,2′-bithiophene (2TF), respectively. The effects of a fluorine substituent on optoelectronic properties are thoroughly investigated. The film absorption onset of PDTPT-2TF is 855 nm, bathochromic-shifted by 24 nm in comparison with that (831 nm) of PDTPT-2T. The lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels of PDTPT-2TF are down-shifted by 0.15 and 0.11 eV relative to those of PDTPT-2T, respectively. X-ray diffraction (XRD) patterns indicate that a more ordered structure is formed in the solid film of PDTPT-2TF. Furthermore, the miscibility between the polymer and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) is significantly improved through the introduction of fluorine. Consequently, PDTPT-2TF exhibits a high PCE of 8.01%, while PDTPT-2T only shows a maximum PCE of 2.65%. The efficiency of 8.01% is the highest one for PT-containing polymers, and more importantly, it is achieved without any processing additives or post-treatments. This work indicates that PT would have great potential as a building block to construct high-performance photovoltaic polymers.

Two novel donor–π–acceptor (D–π–A) type polymers based on indacenodithiophene (IDT) and thieno[3,4-c]pyrrole-4,6-dione (TPD) with thiophene (PIDT-t-TPD) or thieno[3,2-b]thiophene (PIDT-tt-TPD) as π-bridges were designed and synthesized. The π-conjugated backbone length in the repeating unit of the polymer chain was varied by different π-bridges. Both polymers exhibit planar molecular structures, similar broad optical band gaps (Eoptg) and low-lying highest occupied molecular orbital (HOMO) energy levels. However, PIDT-tt-TPD with the more extended π-conjugated backbone shows higher hole mobility and better miscibility with (6,6)-phenyl-C71-butyric acid methyl ester (PC71BM). Polymer solar cells (PSCs) based on PIDT-tt-TPD:PC71BM show the highest power conversion efficiency (PCE) of 5.23% with a short-circuit current density (Jsc) of 11.22 mA cm−2. Considering the limited absorption of PIDT-tt-TPD (400–650 nm), the Jsc value is very impressive. In contrast, PIDT-t-TPD: PC71BM only shows a PCE of 2.47% with a low Jsc of 5.52 mA cm−2. The lower Jsc value of PIDT-t-TPD is consistent with its limited external quantum efficiency (EQE) response (lower than 40%). The present results demonstrate that extending the length of a π-conjugated backbone by an appropriate π-bridge in the D–A polymer improves the photovoltaic performance of PSCs.

Recently, we have used terthiophene side chain to modify benzo[1,2-b:4,5-b']dithiophene (BDT) to form novel building block for BDT polymers. In this paper, this building block is used to copolymerized with thieno[3,4-c]pyrrole-4,6-dione (TPD) and thieno[3,4-b]thiophene (TT). This building block and TPD- or TT-based polymers (P1 and P3) show high open circuit voltage (V-OC) (ca. 0.9-0.95 V) and low energy loss (E-g-eV(OC)) in solar cells devices compared with similar polymers without bulky side chain. We further introduce thiophene pi bridge into these polymers backbone to form two other polymers (P2 and P4). We find this thiophene pi bridge does contribute to this bulky side chained benzodithiophene polymer photovoltaic performances, especially for power conversion efficiencies (PCEs). The polymer solar cells (PSCs) performances are moderate in this article due to the serious aggregation in the PSCs active layer. (C) 2015 Wiley Periodicals, Inc.

In this work, two novel thieno[2,3-f]benzofuran (TBF) unit, with fluorinated alkoxyphenyl or alkylphenyl side chain, were synthesized and characterized. Based on these TBF donor unit and benzodithiophene-4,8-dione (BDD) acceptor, two novel polymers, PTBFPF-BDD and PTBFP-BDD, were prepared by Stille coupling reaction. The conjugated side chain effects on the thermogravimetric, optical, electrochemical, and photovoltaic properties of these polymers were systematically investigated. Both polymers exhibited desirable power conversion efficiency (PCE) of more than 8% after thermal annealing. PTBFP-BDD:ITIC-based devices achieved higher PCE of 8.50% with an open-circuit voltage (VOC) of 0.88 V, a short-circuit current density (JSC) of 16.01 mA/cm2 and a fill factor (FF) of 59.80%. In addition, the devices based on PTBFPF-BDD:ITIC showed an enhanced VOC of 0.92 V due to down-shifted the highest occupied molecular orbital (HOMO) energy levels. The results indicate that the alkylphenyl/alkoxyphenyl substitution of TBF donor units is promising strategy for improving PCE of PSCs.

To avoid the lacquerware of the Nanhai No. 1 shipwreck from being corroded by microorganisms and to improve the knowledge on microbial ecology of the wood lacquers, we conducted a series of tests on the two water samples storing the lacquerware and colonies on the surface of the lacquerware. The high-throughput sequencing detected dominant fungal communities. After that, the fungal strains were isolated and then identified by amplification of ITS- 18S rRNA. Then the activity of ligninolytic and cellulolytic enzymes was detected on potato dextrose agar (PDA) plates with 0.04% (v/v) guaiacol and carboxymethyl cellulose (CMC) agar plates. Finally, we tested the biocide susceptibility of these fungi. Penicillium chrysogenum (NK-NH3) and Fusarium solani (NK- NH1) were the dominant fungi in the sample collected in April 2016 and June 2017. What is more, both showed activity of ligninolytic and cellulolytic enzymes. Four biocidal products (Preventol&reg, D7, P91, BIT 20N, and Euxyl&reg, K100) inhibited the growth of the fungal species in vitro effectively. In further research, the microbial community and environmental parameters in the museum should be monitored to assess the changes in the community and to detect potential microbial outbreaks.

The 2D asymmetric benzodithiophene (BDT) unit is used as a donor unit to construct one new polymer PBDTBDD-Th with benzo[1,2-c:4,5-c']dithiophene-4,8-dione (BDD) as acceptor building block. In comparison to the polymer PBDTsTh-BDD with a side chain containing a sulfur atom, the devices based on PBDTBDD-Th/ITIC show better performance due to the introduction of carbon atoms in the side chain, which could weaken the self-aggregations of polymer chains. As a result, the devices based on PBDTBDD-Th/ITIC blends yield power conversion efficiencies (PCEs) over 10%, much higher than those based on PBDTsTh-BDD/ITIC blends (7.09%). The exciton dissociation probabilities (P diss ) of a device based on PBDTBDD-Th/ITIC blends is 95.3%, which suggests that the device achieves good exciton dissociation and charge transfer. In general, the polymer PBDTBDD-Th shows capability to increase the PCEs of polymer solar cells (PSCs) with a non-fullerene acceptor.

A donor–acceptor (D–A) polymer, PTBFDO-BDD, based on thieno[2,3-f]benzofuran (TBF) with 4-dodecyl thienyl chains, was designed and synthesized. The optical, electrochemical, photovoltaic and device active layer morphology properties of the new polymer were investigated. With the structure of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/PTBFDO-BDD:ITIC/PDINO/Al, polymer solar cells device exhibited a power conversion efficiency (PCE) of 7.15% (AM1.5G, 100 mW cm−2) with VOC of 0.803 V, JSC of 14.71 mA cm−2, and FF of 60.57%. This work demonstrates that thieno[2,3-f]benzofuran-based conjugated polymers are promising as polymer solar cells donor materials.

Utilizing two-dimensional (2-D) conjugated structure and extending two-dimensional π-conjugation system with benzene can improve the performance of the BDT-based polymer solar cells (PSCs). In this work, combining with strong electron-drawing ability of fluorine atom, a new monomer BBFBDT with fluorinated alkoxybiphenyl unit as side-chain was designed and synthesized to construct medium band-gap donor (D) - acceptor (A) copolymer P1 with a benzo[1,2- c:4,5-c’]dithiophene-4,8-dione (BDD) acceptor. Blending with a classical non-fullerene acceptor ITIC, the P1-based PSCs reached a power conversion efficiency (PCE) of 4.16% and when coupled with a fullerene acceptor PC71BM, the PCE of PSCs reached 4.66% with an open-circuit voltage (Voc) of 0.93 V, a short-circuit current density (Jsc) of 9.83 mA cm−2 and a fill factor (FF) of 50.97%. The relatively poor Jsc of P1-based devices may be caused by the bad complementarity of absorption spectra. Furthermore, a wide band-gap D-A copolymer P2, with a electron-deficient 4,7-bis(5-bromothiophen-2-yl)-2-((2-ethylhexyl)oxy)-5,6-difluoro-2H-benzo[d][1,2,3]triazole (TZ) as the acceptor unit, was synthesized to match the absorption spectra of ITIC. Finally, the efficiency achieved 6.59% with Voc of 0.99 V, Jsc of 14.37 mA cm−2 and FF of 46.32%.

In this work, one novel carbazole side chained benzodithiophene (BDT) monomer is designed and synthesized, and this new donor monomer based two D−A conjugated polymers with electron-withdrawing acceptor 4,7-di(4-(2-ethylhexyl)-2-thienyl)-5,6-difluoro-2,1,3-benzothiadiazole (DTffBT) (P5) and benzodithiophene-4,8-dione (BDD) (P7) are prepared. The polymers show 1.65–1.85 eV band gap, which is similar to the polymer with same backbone. The P5 based polymer solar cells show acceptable PCE around 8% and low enegy loss around 0.7 eV, which is similar to the fluorene side-chained polymer. P7 based polymer shows 1 V open-circuit voltage in both fullerene based and fullerene-free polymer solar cells. Molecular conformations, photophysical/electrochemical properties and film morphology of the device active layer blend films were also systematically investigated to reveal the structure−property relationships. This work suggests that carbazole unit is a promising π-conjugated side chain group for BDT monomer to construct efficient two-dimensional (2D) D−A conjugated photovoltaic polymers.

Research on fused-ring small-molecular-acceptors (SMAs) has deeply advanced the development of organic solar cells (OSCs). Compared to fruitful studies of ladder-type cores and end-caps of SMAs, the exploration of side chains is monotonous. The widely utilized alkyl and aryl side chains usually produce a conflicting association between SMAs' crystallinity and miscibility. Herein, a fresh idea about the modification of side chains is reported to explore the subtle balance between the crystallinity and miscibility. Specifically, a phenyl is introduced to the tail of the alkyl side chain whereby a new acceptor IDIC-C4Ph is reported. Moderately weakened crystallinity is observed, while maintaining preferred absorption profiles and face-on orientations. Concurrently, remarkably improved heterojunction morphologies and stacking orientations are detected. PBDB-T:IDIC-C4Ph devices exhibit greater efficiency of 11.50% than devices from alky and aryl modified acceptors. Notably, the as-cast OSCs of PBDB-TF:IDIC-C4Ph reveal outstanding FF over 76% with the best efficiency up to 13.23%. The annealed devices reveal further increased efficiency exceeding 14% with the state of the art FF of 78.32%. Overall, an effective but easily navigable approach is demonstrated to modulate the crystallinity of SMAs toward synergistically improved morphologies and molecular orientations of bulk heterojunction enabling highly efficient OSCs.