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The Heisenberg antiferromagnetic spin-1/2 chain, originally introduced almost a century ago, is one of the best studied models in quantum mechanics due to its exact solution, but nevertheless it continues to present new discoveries. Its low-energy physics is described by the Tomonaga-Luttinger liquid of spinless fermions, similar to the conduction electrons in one-dimensional metals. In this work we investigate the Heisenberg spin-chain compound YbAlO3 and show that the weak interchain coupling causes Umklapp scattering between the left- and right-moving fermions and stabilizes an incommensurate spin-density wave order at q = 2kF under finite magnetic fields. These Umklapp processes open a route to multiple coherent scattering of fermions, which results in the formation of satellites at integer multiples of the incommensurate fundamental wavevector Q = nq. Our work provides surprising and profound insight into bandstructure control for emergent fermions in quantum materials, and shows how neutron diffraction can be applied to investigate the phenomenon of coherent multiple scattering in metals through the proxy of quantum magnetic systems., A field-induced incommensurate spin density wave order was observed in the spin-chain material YbAlO3; however, its mechanism is not fully understood. Here, using neutron scattering and numerical calculations, the authors propose a mechanism based on multiple fermion scattering caused by weak inter-chain coupling.

We designed and synthesized a series of fused-ring electron acceptors (FREAs) based on naphthalene-fused octacyclic cores end-capped by 3-(1,1-dicyanomethylene)-5,6-difluoro-1- indanone (NOICs) using a bottom-up approach. The NOIC series shares the same end groups and side chains, as well as similar fused-ring cores. The butterfly effects, arising from different methoxy positions in the starting materials, impact the design of the final FREAs, as well as their molecular packing, optical and electronic properties, charge transport, film morphology, and performance of organic solar cells. The binary-blend devices based on this NOIC series show power conversion efficiencies varying from 7.15% to 14.1%, due to the different intrinsic properties of the NOIC series, morphologies of blend films, and voltage losses of devices.

Traditional pharmacotherapy suffers from multiple drawbacks that hamper patient treatment, such as the buildup of antibiotic resistances or low drug selectivity and toxicity during systemic application. To overcome these challenges, drug activity can be controlled by employing delivery, targeting, or release solutions that mostly rely on the response to external physicochemical stimuli. Due to various technical limitations, mechanical force as a stimulus in the context of polymer mechanochemistry has so far not been used for this purpose, yet it has been proven to be a convenient and robust method to site-selectively rearrange or cleave bonds with submolecular precision in the realm of materials chemistry. Here, we present an unprecedented mechanochemically responsive system capable of successively releasing small furan-containing molecules, including the furylated fluorophore dansyl and the drugs furosemide as well as furylated doxorubicin, by ultrasound-induced selective scission of disulfide-centered polymers in solution. We show that mechanochemically generated thiol-terminated polymers undergo a Michael-type addition to Diels-Alder (DA) adducts of furylated drugs and acetylenedicarboxylate derivatives, initiating the downstream release of the small molecule drug by a retro DA reaction. We believe that this method can serve as a blueprint for the activation of many other small molecules.

It had been commonly accepted in the organic photovoltaic (OPV) community that subtle variations in the molecular structure of active layer materials would cause profound impacts on their aggregating structure and blend morphology and therefore the performance of such polymer solar cells (PSCs). Herein, we employed an electron-deficient building block 3,6-dithiophenyl-2-carboxylate pyrazine (DTCPz) for constructing one series of promising donor terpolymers of PMZ1, PMZ2, and PMZ3, respectively, gaining their relatively lower-lying highest occupied molecular orbital (HOMO) energy levels, more closed π-π stacking and enhanced crystallinity in thin films, and lower miscibility with acceptor Y6, in comparison with their parent polymer counterpart (namely PM6). Reaching DTCPz moieties up to 20% (mol/mol%) in its terpolymer composition, the resulting polymer (PMZ2) achieved more favorable phase separation with improved exciton dissociation, and charge transport and extraction. As a result, an outstanding fill factor of 77.2% and a promising power conversion efficiency of 17.8 % was achieved. Moreover, the corresponding device shows better thermal stability over the PM6-based one. This work suggests a facile method for significantly improving the thin film morphology of the active-layer materials via fine-tuning the chemical structure of electron-deficient units on the backbone of the wide bandgap donor polymer, therefore achieving enhanced photovoltaic performance and thermal stability for practical applications.

The Heisenberg antiferromagnetic spin-1/2 chain, originally introduced almost a century ago, is one of the best studied models in quantum mechanics due to its exact solution, but nevertheless it continues to present new discoveries. Its low-energy physics is described by the Tomonaga-Luttinger liquid of spinless fermions, similar to the conduction electrons in one-dimensional metals. In this work we investigate the Heisenberg spin-chain compound YbAlO

Herein, we fabricated all-polymer solar cells (all-PSCs) based on a fluorinated wide-bandgap p-type conjugated polymer PM6 as the donor, and a narrow bandgap n-type conjugated polymer PZ1 as the acceptor. In addition to the complementary absorption and matching energy levels, the optimized blend films possess high cystallinity, predominantly face-on stacking, and a suitable phase separated morphology. With this active layer, the devices exhibited a high V oc of 0.96 V, a superior J sc of 17.1 mA cm -2 , a fine fill factor (FF) of 68.2%, and thus an excellent power conversion efficiency (PCE) of 11.2%, which is the highest value reported to date for single-junction all-PSCs. Furthermore, the devices showed good storage stability. After 80 d of storage in the N 2 -filled glovebox, the PCE still remained over 90% of the original value. Large-area devices (1.1 cm 2 ) also demonstrated an outstanding performance with a PCE of 9.2%, among the highest values for the reported large-area all-PSCs. These results indicate that the PM6:PZ1 blend is a promising candidate for scale-up production of large area high-performance all-PSCs.

In this work, a novel narrow-bandgap conjugated polymer acceptor (PN1) based on electron-withdrawing 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis[3-((2-hexyldecyl)oxy)benzene]-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene as the core building block and thiophene as the linking unit was developed and applied in all-polymer solar cells (all-PSCs). The PN1 exhibits a broad and strong absorption in the region of 550–800 nm with a high maximum extinction coefficient of 1.28 × 105 cm−1, a high electron mobility of 9.39 × 10−4 cm2 V−1 s−1 and more ordered molecular packing. In addition, it also possesses a relatively higher lowest unoccupied molecular orbital (LUMO) of −3.85 eV, which is beneficial to improve open circuit voltage (Voc) and reduce the energy loss of the device. By matching with the wide bandgap polymer donor PM6, the all-PSCs achieved a power conversion efficiency (PCE) of 10.5% with a large Voc of 1.0 V, a high short circuit current density (Jsc) of 15.2 mA cm−2 and a superior fill factor (FF) of 0.69. Our work demonstrated that PN1 is a promising polymer acceptor for application in all-PSCs.

Solution-processed perovskite films inevitably have a number of ionic defects, regarded as non-radiative recombination centers, which limit the overall efficiency and the stability of perovskite solar cells (Pero-SCs). Passivation of these defects has been proven to be an efficient strategy to suppress the charge recombination and thus improve the performance of Pero-SCs. Herein, for the first time, a π-conjugated and alcohol-soluble small molecule with bilateral carboxyl and thiophene groups, namely 2,5-di(thiophen-2-yl)terephthalic acid (DTA), was introduced into the MAPbI3-xClx (MA = CH3NH3) film to passivate the defects and enhance the performance of the corresponding planar p-i-n Pero-SCs. With high electron density, the symmetric carboxyl groups on both sides of DTA can effectively coordinate with unsaturated Pb2+ cations to passivate the defects in the perovskite. This efficient defect passivation can reduce the charge trap density and increase the carrier lifetime, which leads to a significant enhancement of the open-circuit voltage from 1.07 V for the control Pero-SC to 1.17 V for the passivated one, resulting in a power conversion efficiency (PCE) of 21.45%. The highest achieved Voc reaches 1.19 V, with a PCE of 21.40%, and the corresponding loss of Voc is only 0.38 V. In addition, the DTA passivated devices exhibit a photovoltaic performance with high reproducibility, as well as a significant improvement in environmental stability and thermal stability. This work demonstrates the great potential of DTA as an effective and promising additive to passivate the perovskite defects for the high performance of Pero-SCs.

Fluorine and alkylsilyl substitutions are two important strategies to reduce the energy levels and increase the absorption coefficient and hole mobility of photovoltaic materials simultaneously. Similar to fluorination, chlorination can also induce the intermolecular non-covalent interactions of Cl-H/S/Cl. Moreover, because chlorine (Cl) atoms contain empty 3d orbitals that can hold π-electrons from the conjugated skeleton, chlorination can decrease the molecular HOMO level more effectively than fluorination. Herein, we developed two wide bandgap polymer donors PBZ-Cl and PBZ-ClSi based on the Cl atom, and combined the Cl atom and alkylsilyl substituted thienyl benzodithiophene (BDTT-Cl and BDTT-ClSi) as donor units, respectively. From the control polymer PBZ to PBZ-Cl and then to PBZ-ClSi, the polymers show a gradually reduced HOMO level, increased absorption coefficient and improved charge mobility. As a result, the PBZ-ClSi:IT-4F-based PSCs fabricated by the nonhalogen solvents achieved a high power conversion efficiency (PCE) of 12.8% with a high open-circuit voltage (V oc ) of 0.93 V, short-circuit current density (J sc ) of 19.2 mA cm -2 , fill factor (FF) of 71.5% and a low energy loss of 0.57 eV, while the PSCs based on PBZ and PBZ-Cl only obtained lower PCEs of 6.4% and 9.7%, respectively. The PCE of 12.8% is one of the highest values recorded for nonhalogen solvent-processed PSCs to date. The results indicate that the combination of Cl atoms and alkylsilyl substituents is a simple and effective method for designing high efficiency polymer photovoltaic materials.

Developing a high-performance donor polymer is critical for achieving efficient non-fullerene organic solar cells (OSCs). Currently, most high-efficiency OSCs are based on a donor polymer named PM6, unfortunately, whose performance is highly sensitive to its molecular weight and thus has significant batch-to-batch variations. Here we report a donor polymer (named PM1) based on a random ternary polymerization strategy that enables highly efficient non-fullerene OSCs with efficiencies reaching 17.6%. Importantly, the PM1 polymer exhibits excellent batch-to-batch reproducibility. By including 20% of a weak electron-withdrawing thiophene-thiazolothiazole (TTz) into the PM6 polymer backbone, the resulting polymer (PM1) can maintain the positive effects (such as downshifted energy level and reduced miscibility) while minimize the negative ones (including reduced temperature-dependent aggregation property). With higher performance and greater synthesis reproducibility, the PM1 polymer has the promise to become the work-horse material for the non-fullerene OSC community., The batch reproducibility of polymer donor materials limits the performance of polymer solar cells. Here Wu et al. develop a polymer donor PM1 by random terpolymerization strategy with a high efficiency of 17.6% in the device and excellent batch-to-batch reproducibility.

Regulating molecular structure to optimize the active layer morphology is of considerable significance for improving the power conversion efficiencies (PCEs) in organic solar cells (OSCs). Herein, we demonstrated a simple ternary copolymerization approach to develop a terpolymer donor PM6-Tz20 by incorporating the 5,5'-dithienyl-2,2'-bithiazole (DTBTz, 20 mol%) unit into the backbone of PM6 (PM6-Tz00). This method can effectively tailor the molecular orientation and aggregation of the polymer, and then optimize the active layer morphology and the corresponding physical processes of devices, ultimately boosting FF and then PCE. Hence, the PM6-Tz20: Y6-based OSCs achieved a PCE of up to 17.1% with a significantly enhanced FF of 0.77. Using Ag (220 nm) instead of Al (100 nm) as cathode, the champion PCE was further improved to 17.6%. This work provides a simple and effective molecular design strategy to optimize the active layer morphology of OSCs for improving photovoltaic performance.

Small molecular acceptors (SMAs) BTC-2F and BTH-2F, based on heptacyclic benzodi(cyclopentadithiophene) electron-donating core (CBT) with chlorinated-thienyl conjugated and thienyl conjugated side chains, respectively, are designed and synthesized. Compared with non-chlorine acceptor BTH-2F, BTC-2F exhibits slightly blue-shifted absorption spectra, similar the lowest unoccupied molecular orbital (LUMO) (–3.91 eV), deeper highest occupied molecular orbital (HOMO) energy level and higher electron mobility than that of BTH-2F. PM6, a wide bandgap polymer, is selected as the donor material to construct bulk heterojunction polymer solar cells processed with nonhalogenated solvent toluene. The optimized PM6:BTC-2F-based device presents a 12.9% power conversion efficiency (PCE), while the PCE of PM6:BTH-2F-based device is only 11.3%. The results suggest that it is an effective strategy to optimize the photoelectric properties of SMAs by incorporating chlorine atom into the conjugated side chains.

To further elevate the power conversion efficiency (PCE) of organic solar cells (OSCs), ternary strategy is one of the most efficient methods via simply incorporating a suitable third component. Here, a nonfullerene small molecule acceptor MOITIC was incorporated into the state-of-art PM6:Y6 binary system to further enhance the photovoltaic performance. Detailed investigation revealed that MOITIC exhibited a good miscibility and compatibility with Y6, forming alloy-like acceptors in the ternary blends. The alloy-like phase promoted the phase separation and optimized the morphology of ternary blend, which afforded higher and more balanced carrier mobility and reduced charge recombination in devices. Moreover, the larger energy offset between PM6 and MOITIC:Y6 acceptor alloy is beneficial to enhance open-circuit voltage (Voc) of corresponding devices. As a consequence, the optimized ternary OSC (PM6:Y6:MOITIC = 1:1:0.1) showed a significantly increased PCE of 17.1% with simultaneously enhanced Voc of 0.882 V, short-circuit current density (Jsc) of 25.6 mA cm−2, and fill factor (FF) of 75.7%, which has about 9% enhancement compared to the control binary PM6:Y6 (15.7%). In addition, the optimized ternary device exhibited better stability. This work indicates that ternary strategy via combining two compatible small molecule acceptors is effective to simultaneously improve the efficiency and stability of OSCs.

A series of bisindolylmaleimide dyes (IMs) with different N-substituents (IM-PFB, IM-TBA and IM-MB) and planarity (IMC-MB and IM-MB) were designed and synthesized to detect anions selectively and sensitively. The anion-sensing properties were investigated systematically by changing the N-substituents of maleimide, solvent type and molecular planarity. Results indicate that the anion recognition is significantly affected by the solvent type rather than the N-substituents. Different anion sensitivity in various solvents makes IMs selectively detect F− in ACN, H2PO4− in DCM and CN− in THF. Due to the fixed location of two NH groups, the dye IMC-MB with planar structure exhibits poor sensing selectivity in various solvents. The titration curves of anions show that the sensing mechanism of IMs in various solvents for anions is different. The further experimental and DFT/TDDFT calculation results demonstrate that the hydrogen bond interaction and deprotonation of one H atom take place in DCM and THF, respectively, and that the two interactions synchronously exist in ACN. Interestingly, the solvent-dependent anion recognition can make IM-PFB mimic the function of three kinds of decoders (1-to-2, 2-to-3 and 2-to-4), a 4-to-2 encoder and a 1 : 2 demultiplexer. It is really rare for one molecule to mimic so many logic operations.

To achieve efficient polymer solar cells (PSCs), it is important to overcome the energy loss (Eloss) from the optical bandgap to the open-circuit voltage (Voc) of the device by properly matching donor/acceptor (D/A) photovoltaic materials. Here, we develop efficient PSCs based on the absorption complementary pairs of halogenated polymer donors (PM6 and PM7) and an asymmetrical non-fullerene acceptor (IDT6CN-M). The D/A pairs of PM6:IDT6CN-M and PM7:IDT6CN-M show very small highest occupied molecular orbital offsets (ΔEHOMO) of 0.10 and 0.08 eV due to the fact that the halogenation decreases the HOMO levels of polymers, which helps the PSCs achieve a high Voc of 1.04 and 1.05 V, and a small Eloss of 0.56 and 0.55 eV, respectively. Our studies show that the D/A pairs have good morphology compatibility, and the related devices have efficient photon capture and exciton dissociation, balanced and efficient charge transfer and extraction processes. As a result, the PSCs based on PM6:IDT6CN-M and PM7:IDT6VN-M achieved the same high device efficiency of 13.3%, which is one of the highest values for single-junction PSCs with a Voc of over 1.0 V.

Regulating molecular ordering and nanoscale morphology of photoactive layer is crucial to achieve high carrier mobility for fabricating thick-film organic solar cells (OSCs). Herein, molecular ordering and phase separation were finely controlled by varying the substrate temperature in blade-coated PM6:IT-4F devices. The blade-coated devices with low substrate temperature (30 °C) show low crystallinity of IT-4F and poor device performance. However, a high power conversion efficiency (PCE) of 13.64% was achieved for the device blade-coated at 50 °C in air without any other processing treatments, due to the well-ordered molecular packing along the backbone direction of IT-4F molecules. When the film thickness increased to 400 nm, an excellent PCE of 10.22% was achieved in the device blade-coated at 70 °C, which is higher than that of the optimal device blade-coated at 50 °C. This was attributed to the much improved crystallinity within the long-range ordered side-chain packing of IT-4F molecules and the newly emerged small-scale phase separation providing purer domains and continuous charge transport channels. Furthermore, large-Area (90 mm2) devices exhibit high PCEs of 11.39% and 9.76% with a 56 mm2 aperture at film thicknesses of 135 nm and 306 nm, respectively. In addition, the device blade-coated at 70 °C exhibits good storage stability. This work provides comprehensive guidance for optimizing the molecular ordering and nanoscale morphology to fabricate high-efficiency thick-film OSCs.

A novel wide-bandgap conjugated polymer (PTZP) based on alkylphenyl-substituted benzo[1,2-b:4,5-b′]dithiophene (BDT-P) as the electron-rich unit and thiazolo[5,4-d]thiazole (TTz) as the electron-deficient unit was designed and synthesized for the non-fullerene polymer solar cell (PSCs) application. The polymer exhibited a wide bandgap of 2.01 eV with a strong absorption in the range of 300-620 nm, which was complementary with that of the fused-ring small molecule acceptor (SMA; 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, IDIC). Also, the polymer exhibits a deep highest occupied molecular orbital (HOMO) energy level of -5.41 eV. Furthermore, the polymer film possesses strong crystallinity and dominated face-on stacking with a small d-spacing of 3.65 Å, resulting in a high hole mobility of 4.01 × 10-3 cm2 V-1 s-1. The optimal PSCs based on the PTZP:IDIC blend showed a high PCE of 11.8% with an open-circuit voltage (Voc) of 0.90 V, a short-circuit current density (Jsc) of 17.9 mA cm-2 and a fill factor (FF) of 73.3%. Moreover, the device with an active layer thickness of up to 200 nm or area of up to 0.81 cm2 exhibited outstanding performance, with PCE of over 10%, resulting from the excellent molecular stacking. These results revealed that PTZP will be a promising conjugated polymer for the fabrication of efficient large-area PSCs.