•We demonstrated the synthesis of dialkylthiobenzo[1,2-b:4,5-b′]dithiophene based polymers.•We demonstrated the electrochemical characterization and molecular simulation of polymers.•We demonstrated the enhanced cell performance using solvent additive.•We demonstrated the highest PCE of 7.65% for PBDT-DTBTff based OPVs.In this study, three copolymers containing bisalkylthio side chain modifying two-dimensional benzo[1,2-b:4,5-b′]dithiophene (BDT) donor with different electron-deficient acceptors were synthesized. The copolymers were characterized using a combination of thermal analysis, UV–visible spectroscopy, cyclic voltammetry, and theoretical calculations. All copolymers exhibit deep HOMO energy levels from −5.52 eV to −5.60 eV, correspondingly resulting in high VOC. The photovoltaic properties of the copolymers were also studied systematically. The best devices blending PBDT-DTBTff with PC71BM exhibited a best PCE of 7.65%, with a VOC of 0.86 V, a JSC of 13.32 mA cm−2 and a FF of 66.8% due to its high hole mobility (1.1 × 10−3 cm2 V−1 s−1) and facilitated exciton dissociation and charge transport. This work demonstrates an effective method to tune HOMO energy levels of BDT-based copolymers through introducing bisalkylthio side chain into BDT donor. And this result also demonstrates the significance of the interaction and match between donor-acceptor units providing related polymer with suitable band gap and HOMO/LUMO energy levels.

•An integration strategy was presented to construct Ni3S2 based hierarchical composite.•Nanowhisker Ni3S2 were densely integrated onto halloysite nanotubes.•The well-designed electrode exhibits remarkable capacitance and cycling stability.•This strategy provides good reference to electrode materials design for energy storageCost-effective and robust energy storage systems have attracted great attention for portable electronic devices. Three-dimensional electrodes can effectively enhance the charge transfer, increase the mechanical stability and thus improve the electrochemical performance upon continuous charge-discharge. The earth abundant halloysite nanotubes (HNTs) have shown immense potential in constructing nanoarchitectural composites. Here, we first demonstrate the development of hybrid composite of nickel sulfide (Ni3S2) and HNTs with glucose as binders for efficient energy storage in supercapacitor. The surface sulfhydrylation of HNTs and glucose-assisted hydrothermal reaction are crucial for the preparation of well-structured composite. Due to the synergistic effect between components, the Ni3S2/HNTs@HS composite electrode delivers a capacity of 450.4C g−1 and high retention of 82.6% over 2000 cycles in three-electrode supercapacitors. Moreover, the Ni3S2/HNTs@HS//Whatman paper//Ni3S2/HNTs@HS two-electrode symmetric supercapacitor exhibits a maximum potential window of 1.3 V, with a capacity of 250C g−1 and performance loss of only 18.2% over 2000 cycling at 1 A g−1. A maximum energy density of 79.6 Wh kg−1 is achieved at a power density of 1.03 kW kg−1. Such excellent energy storage performance suggests the great potential of Ni3S2/HNTs@HS for high-efficiency energy storage systems.Download high-res image (188KB)Download full-size imageHalloysite nanotubes, earth abundant alumosilicate tubular clay, are used to construct hierarchical composite with nickel sulfide (Ni3S2) via glucose-assisted hydrothermal reaction. The composite electrode shows high specific capacitance and cycling stability in supercapacitors. Results from this work provide insights into synthetic control of composition and morphology of hybrid composites and electrochemical properties of metal oxide/sulfide electrode.

•The synthesis of bisalkylthiobenzo[1,2-b:4,5-b']dithiophene based oligomers.•The electrochemical characterization and molecular simulation of oligomers.•The effect of ending acceptor on bisalkylthio BDT oligomer properties.•The highest PCE of 5.17% for oligomer based OPVs.Three novel small molecules named DR3TDST, DRCN3TDST and DB3TDST containing bisalkylthiothienyl side-chain on benzo[1,2-b:4,5-b']dithiophene (BDT) core with different electron-deficient ending-groups are designed and synthesized. All three molecules have deep HOMO energy level from −5.40 eV to −5.44 eV, indicating introduction of bisalkylthio group to BDT is an effective method to modulate the molecular energy levels. Different ending-groups exhibit small but measurable effects on absorption, energy level, charge transport, morphology, and photovoltaic properties of small molecules. Bulk heterojunction solar cells fabricated with DRCN3TDST and PC71BM deliverer the highest power conversion efficiency (PCE) of 5.17% after annealing and solvent vapor annealing.Benzo[1,2-b:4,5-b']dithiophene (BDT) core-structured small molecules with bisalkylthio side-group lowered HOMO levels showed the highest power conversion efficiency (PCE) of 5.17% in OSCs.Download high-res image (230KB)Download full-size image

•Cabazole-based hole-transporting material CZ-TA was developed via one-step synthesis.•Perovskite solar cells (PVSCs) with 50 nm CZ-TA film achieved a maximum PCE of 18.32%, comparable to that with 200 nm spiro-OMeTAD.•CZ-TA improved the hole extraction and transport to afford impressive fill factors over 81%.•The unit cost of CZ-TA hole-transporting layer was only 1/80 of that of spiro-OMeTAD, paving its way for commercialization of low-cost PVSC technology.A carbazole-based hole-transporting material named 4,4′,4′′,4′′′-(9-octylcarbazole-1,3,6,8-tetrayl) tetrakis(N,N-bis(4-methoxyphenyl)aniline) (CZ-TA) has been developed through a one-step facile synthesis approach. The solution-processed planar perovskite solar cells (PVSCs) with 50 nm thick CZ-TA hole selective layer (HSL) contributes a power conversion efficiency of 18.32%, comparable to the most commonly used 200 nm spiro-OMeTAD (18.28%) HSLs. The improved hole extraction, transport and reduced recombination are found to endow CZ-TA-based devices with impressive fill factors over 81.0%. Importantly, the unit cost of HSL in PVSCs using CZ-TA can be as low as only 1/80 of that of spiro-OMeTAD, indicating that CZ-TA could be a promising candidate as HSLs for commercialization of the low-cost PVSC technology.One-step facilely synthesized carbazole-cored hole transport material has afforded the solution-processed perovskite solar cells with a maximum power conversion efficiency of 18.32%, comparable to that of the mostly used spiro-OMeTAD. The unit cost of hole transport layer can be cut down to 1/80 of that of spiro-OMeTAD by using this new material.Download high-res image (224KB)Download full-size image

In this work, a highly efficient parallel connected tandem solar cell utilizing a nonfullerene acceptor is demonstrated. Guided by optical simulation, each of the active layer thicknesses of subcells are tuned to maximize its light trapping without spending intense effort to match photocurrent. Interestingly, a strong optical microcavity with dual oscillation centers is formed in a back subcell, which further enhances light absorption. The parallel tandem device shows an improved photon-to-electron response over the range between 450 and 800 nm, and a high short-circuit current density (J SC) of 17.92 mA cm−2. In addition, the subcells show high fill factors due to reduced recombination loss under diluted light intensity. These merits enable an overall power conversion efficiency (PCE) of >10% for this tandem cell, which represents a ≈15% enhancement compared to the optimal single-junction device. Further application of the designed parallel tandem configuration to more efficient single-junction cells enable a PCE of >11%, which is the highest efficiency among all parallel connected organic solar cells (OSCs). This work stresses the importance of employing a parallel tandem configuration for achieving efficient light harvesting in nonfullerene-based OSCs. It provides a useful strategy for exploring the ultimate performance of organic solar cells.

A new small molecule-based hole selective material (HSM), 4,4′,4′′-(7,7′,7′′-(5,5,10,10,15,15-hexahexyl-10,15-dihydro-5H-diindeno[1,2-a:1′,2′-c]fluorene-2,7,12-triyl)tris(2,3-dihydrothieno[3,4-b][1,4]dioxine-7,5-diyl))tris(N,N-bis(4-methoxyphenyl)aniline) (TRUX-E-T), has been developed by a facile synthesis with reduced cost. The highest occupied molecular orbital energy level and lowest unoccupied molecular orbital energy level of TRUX-E-T are −5.10 and −2.50 eV, respectively, making it a suitable HSM for lead iodide perovskite solar cells. TRUX-E-T can be smoothly deposited onto perovskite layers, enabling efficient perovskite solar cells with thin TRUX-E-T layers (∼50 nm), which helps cut the unit cost of the HSL used in PVSCs to approximately one-fortieth (1/40) of 2,2′,7,7′-tetrakis (N,N-di-p-methoxyphenylamino)-9,9′-spirobifluorene (spiro-OMeTAD). Additionally, TRUX-E-T exhibits hole mobilities as high as 2.47 × 10−4 cm2 V−1 s−1, better than spiro-OMeTAD. As a result, our perovskite solar cells using TRUX-E-T have shown high fill factors up to 82%. The champion cell achieved a maximum power conversion efficiency of 18.35% (16.44%) when measured under reverse (forward) voltage scan under AM1.5 G 100 mW cm−2 illumination. Our un-encapsulated cells exhibited good stability in ambient air, maintaining 96.4% of their initial efficiency of 18.35% after 20 days of storage.

Fluorescent sensors based on semiconductor quantum dots (QDs) have been immensely investigated for achiral molecular recognition. For chiral discrimination of amino acids (AAs), we herein report a versatile fluorescent sensor, i.e., CdTe QDs encapsulated with cyclodextrin (CD) clicked silica via layer-by-layer modification. The as-obtained hybrid molecular recognition platform exhibited excellent chirality sensing of AAs at micromolar concentrations in water. By taking advantage of the inclusion complexation of CD and the optical properties of the QD core, chiral discrimination was realized on the basis of the different binding energies of the CD-AA enantiomer complexes, as revealed using density-functional theory calculation. The fluorescent probe exhibited linearly enhanced photoluminescence with increased concentration of D-histidine at 0–60 μM and L-histidine at 0–20 μM. These water-soluble fluorescent sensors using a chiral host with a covalently linked chromophore may find applications in the robust sensing of a wide range of achiral and chiral molecules in water.

•The facile synthesis of dialkylthiobenzo[1,2-b:4,5-b']difuran.•The electrochemical characterization of polymer PBDFs-DTBTff.•The enhancement of solvent additive and THF vapor treatment on device performance.•The demonstration of the highest PCE of 5.48% for PBDFs-DTBTff based devices.The facile synthesis of dialkylthio substituted benzo[1,2-b:4,5-b′]difuran unit via a straightforward palladium-catalyzed carbon–sulfur bond formation reaction is reported. A novel donor–acceptor alternating copolymer was further developed by Stille coupling. The optical and electrochemical properties of the polymer have been carefully studied. The photovoltaic performance by blending the copolymer with [6,6]-phenyl-C71-butyric acid methyl ester were explored in both conventional and inverted solar cell devices. Solvent additive and vapor treatment exhibit positive effects on the device performance. The best devices delivered a power conversion efficiency of 5.48%, with an active layer processed from chloroform solutions with 1,8-diiodooctane (3%) and 30 s tetrahydrofuran vapor treatment.

•The preparation of cationic cyclodextrin (CD) clicked chiral stationary phase (CSP).•The enantioseparation 21 recemates with the CD clicked CSP in both reversed phase and normal-phase high-performance liquid chromatography.•The fine-tuned enantioselectivity of CD CSP with the polarity of mobile phase using organic modifier.•The excellent chiral resolutions readily achieved with CD clicked CSP.In this work, a novel cationic cyclodextrin (CD) chiral stationary phase (CSPs) has been developed by clicking 6A-azido-6C-[(3-methoxylpropyl)-1- ammonium]-heptakis[2,3-di-O-(3-chloro-4-methylphenylcarbamate)-6B,6D,6E,6F,6G-pentakis-O-per(3-chloro-4-methylphenylcarbamate)-β-CD chloride onto alkynyl silica support. The enantioselectivies of the as-obtained novel CSP were evaluated using 21 model racemates including flavonoids, aromatic alcohols, acidic drugs, β-blocker and amino acids. Good enantioseparations were achieved in polar-organic phase high performance liquid chromatography (HPLC), with the highest resolution of 8.07 observed for 7-methoxyflavanone. The enantioseparations in normal-phase HPLC were fine-tuned with the polarity of the mobile phase with different alcohols as organic modifiers. Improved chiral resolutions of analytes but longer retention were observed in mobile phases with decreased polarity. On comparison with previously reported clicked CD CSP, the cationic CD clicked CSP exhibited better enenatioseparations for selected racemates even in normal-phase HPLC. The results indicate that 3-methoxypropylammonium and phenylcarbamoylated moieties of the cationic CSP may provide intermolecular interactions such as hydrogen bonding, π–π conjugation and dipole–dipole besides inclusion complexation to drive the enantioseparation.

A general methodology has been proposed for the straightforward access to 4,8-functionalized benzo[1,2-b:4,5-b′]dithiophenes (BDTs) via Pd mediated coupling reactions including Suzuki–Sonogashira coupling and carbon–sulfur bond formation reactions. This versatile platform can be used to construct a library of BDT core centred conjugated systems, featuring large fused-ring structure and good charge mobility, where a hole mobility of 0.061 cm2 V−1 s−1 is demonstrated. With the energy level fine-tuned with functionalization, the charge transporting BDTs show great potential for donor–acceptor polymers.

A two-dimensional (2D) low bandgap polymer (PDTS-Ph-TTz) based on dithieno[3,2-b:2′,3′-d]silole (DTS) with phenyl substitution on the bridging silicon atom and thiazolo[5,4-d]thiazole (TTz) was designed and synthesized for photovoltaic applications. The impact of conjugated side chains on the optical, electrochemical and energy levels of the polymer was studied. The phenyl substituted DTS polymer exhibited a 0.16 eV down-shifted highest occupied molecular orbital (HOMO) energy level and ca. 0.1 eV narrowed bandgap in comparison to the corresponding polymers with alkyl substitution on the silicon bridge. The influence of the blend weight ratio, the PFN layer, mixed solvent, THF exposure and polar solvent treatment and thermal annealing on the performance of PDTS-Ph-TTz:PC71BM devices was studied. PDTS-Ph-TTz:PC71BM (1:1, weight ratio) devices delivered the highest power conversion efficiency of 2.14% by using the PFN layer and THF annealing. Thermal annealing was found to exert a negative effect on the device performance. The morphology evolution of blend films processed with different solvents explained the difference in device performance. The results indicate that phenyl substitution is an effective way to tune the HOMO and bandgap of polymer donors for enhanced photovoltaic performance with the as-demonstrated 2D-conjugated DTS structure.

The baseline enantioseparation of 19 racemic drugs including ondansetron, citalopram, galanthamine base, pregabalin, timolol, atenolol, tropicamide, ephedrine hydrochloride, flavanoids and aryl alcohols has been successfully achieved with a cyclodextrin clicked chiral stationary phase in high performance liquid chromatography. The best separation results were presented under optimized conditions. The effect of organic modifiers including methanol and acetonitrile on the enantioseparation of racemates was also studied. Chiral resolutions of 4.19 and 4.42 were achieved for citalopram and tropicamide, respectively.

Two-dimensional polyfluorenes bearing thienylenevinylene-bridged malononitrile (PF-BTDCN) or diethylthiobarbituric acid accepting side chains (PF-BTDTA) have been successfully prepared. The polymers were fully characterized for their physicochemical, electrochemical, and photovoltaic properties. These polymers exhibited greatly changed properties with the introduction of π-conjugated accepting side chains. The enhancement of current density for the bulk-heterojunction solar cells was observed when replacing the PEDOT:PSS interfacial layer with molybdenum oxide (MoO3). Photovoltaic solar cells with the configuration ITO/MoO3/polymer:PCBM/Al exhibited an efficiency of 3.13% and 1.72% for PF-BTDCN and PF-BTDTA, respectively. A morphology study revealed the existence of nanoscale phase separation with interpenetration networks between polymer and PCBM domains.

A general methodology has been proposed for the straightforward access to 4,8-functionalized benzo[1,2-b:4,5-b′]dithiophenes (BDTs) via Pd mediated coupling reactions including Suzuki–Sonogashira coupling and carbon–sulfur bond formation reactions. This versatile platform can be used to construct a library of BDT core centred conjugated systems, featuring large fused-ring structure and good charge mobility, where a hole mobility of 0.061 cm2 V−1 s−1 is demonstrated. With the energy level fine-tuned with functionalization, the charge transporting BDTs show great potential for donor–acceptor polymers.

A two-dimensional (2D) low bandgap polymer (PDTS-Ph-TTz) based on dithieno[3,2-b:2′,3′-d]silole (DTS) with phenyl substitution on the bridging silicon atom and thiazolo[5,4-d]thiazole (TTz) was designed and synthesized for photovoltaic applications. The impact of conjugated side chains on the optical, electrochemical and energy levels of the polymer was studied. The phenyl substituted DTS polymer exhibited a 0.16 eV down-shifted highest occupied molecular orbital (HOMO) energy level and ca. 0.1 eV narrowed bandgap in comparison to the corresponding polymers with alkyl substitution on the silicon bridge. The influence of the blend weight ratio, the PFN layer, mixed solvent, THF exposure and polar solvent treatment and thermal annealing on the performance of PDTS-Ph-TTz:PC71BM devices was studied. PDTS-Ph-TTz:PC71BM (1:1, weight ratio) devices delivered the highest power conversion efficiency of 2.14% by using the PFN layer and THF annealing. Thermal annealing was found to exert a negative effect on the device performance. The morphology evolution of blend films processed with different solvents explained the difference in device performance. The results indicate that phenyl substitution is an effective way to tune the HOMO and bandgap of polymer donors for enhanced photovoltaic performance with the as-demonstrated 2D-conjugated DTS structure.

The baseline enantioseparation of 19 racemic drugs including ondansetron, citalopram, galanthamine base, pregabalin, timolol, atenolol, tropicamide, ephedrine hydrochloride, flavanoids and aryl alcohols has been successfully achieved with a cyclodextrin clicked chiral stationary phase in high performance liquid chromatography. The best separation results were presented under optimized conditions. The effect of organic modifiers including methanol and acetonitrile on the enantioseparation of racemates was also studied. Chiral resolutions of 4.19 and 4.42 were achieved for citalopram and tropicamide, respectively.