Microwave photonics frequency measurement with improved accuracy based on an artificial neural network.

Photonics-assisted techniques for microwave frequency measurement (MFM) show great potential for overcoming electronic bottlenecks, with wild applications in radar and communication. The MFM system based on the stimulated Brillouin scattering (SBS) effect can measure the frequency of multiple high-frequency and wide-band signals. However, the accuracy of the MFM system in multi-tone frequency measurement is constrained by the SBS bandwidth and the nonlinearity of the system. To resolve this problem, a method based on an artificial neural network (ANN) is suggested, which can establish a nonlinear mapping between the measured two-tone signal spectra and the theoretical frequencies. Through simulation verification, the ANN optimized frequencies within the range of (0.5, 27) GHz of the MFM system show 79%, 76%, 70%, 44% reduction in errors separately under four spectral signal-to-noise ratios (SNR) conditions, 20 dB, 15 dB, 10 dB, 0 dB, and the frequency resolution is improved from 30 MHz to 10 MHz.

A-D-A Molecule-Bridge Interface for Efficient Perovskite Solar Cells and Modules.

As the photovoltaic field endeavors to transition perovskite solar cells (PSCs) to industrial applications, inverted PSCs, which incorporate fullerene as electron transport layers, have emerged as a compelling choice due to their augmented stability and cost-effectiveness. However, these attributes suffer from performance issues stemming from suboptimal electrical characteristics at the perovskite/fullerene interface. To surmount these hurdles, an interface bridging strategy (IBS) is proposed to attenuate the interface energy loss and enhance the interfacial stability by designing a series of A-D-A type perylene monoimide (PMI) derivatives with multifaceted advantages. In addition to passivating defects, the IBS plays a crucial role in facilitating the binding between perovskite and fullerene, thereby enhancing interface coupling and importantly, improving the formation of fullerene films. The PMI derivatives, functioning as bridges, serve as a protective barrier to enhance the device stability. Consequently, the IBS enables a remarkable efficiency of 24.62% for lab-scale PSCs and an efficiency of 18.73% for perovskite solar modules craft on 156 × 156 mm2 substrates. The obtained efficiencies represent some of the highest recorded for fullerene-based devices, showcasing significant progress in designing interfacial molecules at the perovskite/fullerene interface and offering a promising path to enhance the commercial viability of PSCs.

Modular-Approach Synthesis of Giant Molecule Acceptors via Lewis-Acid-Catalyzed Knoevenagel Condensation for Stable Polymer Solar Cells.

The operational stability of polymer solar cells is a critical concern with respect to the thermodynamic relaxation of acceptor-donor-acceptor (A-D-A) or A-DA'D-A structured small-molecule acceptors (SMAs) within their blends with polymer donors. Giant molecule acceptors (GMAs) bearing SMAs as subunits offer a solution to this issue, while their classical synthesis via the Stille coupling suffers from low reaction efficiency and difficulty in obtaining mono-brominated SMA, rendering the approach impractical for their large-scale and low-cost preparation. In this study, we present a simple and cost-effective solution to this challenge through Lewis acid-catalyzed Knoevenagel condensation with boron trifluoride etherate (BF3 ⋅ OEt2 ) as catalyst. We demonstrated that the coupling of the monoaldehyde-terminated A-D-CHO unit and the methylene-based A-link-A (or its silyl enol ether counterpart) substrates can be quantitatively achieved within 30 minutes in the presence of acetic anhydride, affording a variety of GMAs connected via the flexible and conjugated linkers. The photophysical properties was fully studied, yielding a high device efficiency of over 18 %. Our findings offer a promising alternative for the modular synthesis of GMAs with high yields, easier work up, and the widespread application of such methodology will undoubtedly accelerate the progress of stable polymer solar cells.

[Effect and Mechanism of Epimedium Polysaccharide on Bone Marrow Hematopoietic Function and Th17/Treg Balance in Aplastic Anemia].

OBJECTIVE: To observe the effects of Epimedium polysaccharides (EPS) on bone marrow hematopoietic function and Th17/Treg balance in aplastic anemia (AA) mice, and preliminarily explore its therapeutic mechanism. METHODS: Forty BALB/C mice were randomly divided into control (control), model (model), stanozolol (stanozolol) and epimedium polysaccharide (EPS) group, with 10 mice in each group. Except for the control group, Acetophenazine, Gy irradiation and cyclophosphamide triple application were used to establish AA models for the other groups. After the model was established, the stanozolol group was intragastrically administered with 4 mg/kg stanozolol suspension, the EPS group was intragastrically administered with 100 mg/kg epimedium polysaccharide, while the control group and the model group were given an equal volume of 0.9% sodium chloride solution by gavage once a day, for 14 consecutive days. The automatic animal blood analyzer was used to detect the changes in peripheral blood hemoglobin (Hb), red blood cells (RBC), white blood cells (WBC) and platelets (PLT), flow cytometry was used to detect the proportion of Treg and Th17 cells, the levels of interleukin 2 (IL-2), interleukin 11 (IL-11) and tumor necrosis factor α (TNF-α) were detected by ELISA, the number of nucleated bone marrow cells was counted, HE staining and immunohistochemical staining were used to detect the number, the proliferation and apoptosis of bone marrow cells, Western blot was used to detect the expression of signal transducer and activator of transcription 3 (STAT3), retinoic acid receptor-related orphan receptor γ (RORγt), transducer and activator of transcription 5 (STAT5) and fork head transcription factor 3 (Foxp3). RESULTS: Compared with the model group, the levels of Hb, RBC, WBC and PLT in the peripheral blood of mice in stanozolol and EPS group significantly increased, the proportion of Th17 cells was significantly reduced, and the proportion of Treg cells significantly increased. The levels of IL-2 and TNF-α in serum were significantly reduced (P<0.05), the level of IL-11 significantly increased (P<0.05), the number of bone marrow nucleated cells significantly increased (P<0.05), the positive rate of Ki-67 significantly increased (P<0.05) and the positive rate of Caspase-3 was significantly reduced (P<0.05). At the same time, the protein expression of STAT3 and RORγt significantly decreased, and the protein expression of STAT5 and Foxp3 increased, the difference showed statistically significant (P<0.05). CONCLUSION: EPS can promote the recovery of bone marrow hematopoietic function in AA mice and improve Th17/Treg imbalance, the mechanism may be related to the inhibition of STAT3/RORγt expression and promotion of STAT5/Foxp3 expression.

Layer-by-Layer Solution-Processed Organic Solar Cells with Perylene Diimides as Acceptors.

Layer-by-layer (LBL) sequential solution processing of the active layer has been proven as an effective strategy to improve the performance of organic solar cells (OSCs), which could adjust vertical phase separation and improve device performance. Although perylene diimide (PDI) derivatives are typical acceptors with excellent photoelectric properties, there are few studies on PDI-based LBL OSCs. Herein, three PDI acceptors (TBDPDI-C5, TBDPDI-C11, and SdiPDI) were used to fabricate LBL and bulk heterojunction (BHJ) OSCs, respectively. A series of studies including device optimization, photoluminescence (PL) quenching, dependence of light intensity, carrier mobility, atomic force microscopy (AFM), transmission electron microscopy (TEM), grazing-incidence wide-angle X-ray scattering (GIWAXS), and depth analysis X-ray photoelectron spectroscopy (DXPS) were carried out to make clear the difference of the PDI-based LBL and BHJ OSCs. The results show that LBL OSCs possess better charge transport, higher and more balanced carrier mobility, less exciton recombination loss, more favorable film morphology, and proper vertical component distribution. Therefore, all the three PDI acceptor-based LBL OSCs exhibit higher performance than their BHJ counterparts. Among them, TBDPDI-C5 performs best with a power conversion efficiency of 6.11% for LBL OSCs, higher than its BHJ OSC (5.14%). It is the first time for PDI small molecular acceptors to fabricate high-efficiency OSCs by using an LBL solution-processed method.

Silicon Naphthalocyanine Tetraimides: Cathode Interlayer Materials for Highly Efficient Organic Solar Cells.

Naphthalocyanine derivatives (SiNcTI-N and SiNcTI-Br) were firstly used as excellent cathode interlayer materials (CIMs) in organic solar cells, via introducing four electron-withdrawing imide groups and two hydrophilic alkyls. Both of them showed deep LUMO energy levels (below -3.90 eV), good thermal stability (Td >210 °C), and strong self-doping property. The SiNcTI-Br CIM displayed high conductivity (4.5×10-5  S cm-1 ) and electron mobility (7.81×10-5  cm2 V-1 s-1 ), which could boost the efficiencies of the PM6:Y6-based OSCs over a wide range of CIM layer thicknesses (4-25 nm), with maximum efficiency of 16.71 %.

"Double-Acceptor-Type" Random Conjugated Terpolymer Donors for Additive-Free Non-Fullerene Organic Solar Cells.

Random conjugated terpolymers (RCTs) not only promote great comprehension and realization for the state-of-the-art highly effective non-fullerene organic solar cells (OSCs) but also offer a simple and practical synthetic strategy. However, the photovoltaic properties of RCTs yet lagged behind that of the donor-acceptor (D-A) alternating copolymer, especially in additive-free devices. Hence, we developed two feasible "double-acceptor-type" random conjugated terpolymers, PBDB-TAZ20 and PBDB-TAZ40. The additive-free OSCs based on PBDB-TAZ20:ITIC and PBDB-TAZ40:ITIC exhibit decent efficiencies of 12.34 and 11.27%, respectively, which both surpass the PBDB-T:ITIC-based device. For RCTs, the reasonably weakened crystallinity and the reduced phase separation degree are demonstrated to help in improving charge transport, reducing bimolecular recombination, and thus enhancing the photovoltaic performance of additive-free OSCs. The results imply that adding a third moiety into the D-A polymer donors provides a simple but efficient synthetic approach for high-performance OSCs.

Thioether Bond Modification Enables Boosted Photovoltaic Performance of Nonfullerene Polymer Solar Cells.

A small-molecule nonfullerene acceptor, ITIC-S, bearing a fused heptacyclic benzodi(cyclopentadithiophene) core with a thioether-bond-substituted thiophene, is designed, synthesized, and compared with its alkyl-substituted analog, ITIC2. Compared with ITIC2, ITIC-S with a thioether bond exhibits higher electron mobility, a slightly larger optical band gap, and similar absorption. The active layer incorporating ITIC-S and the wide-bandgap polymeric donor PBDB-T-SF displays a smaller crystalline coherent length of π-π stacking, more balanced mobilities, weaker bimolecular recombination, and more effective charge collection than its PBDB-T-SF:ITIC2 counterpart. Accordingly, polymer solar cells incorporating ITIC-S and PBDB-T-SF demonstrate a fill factor (FF) of 66.8% and a champion power conversion efficiency (PCE) of 11.6%, exceeding those of the PBDB-T-SF:ITIC2 blend (PCE = 10.1%, FF = 59.7%), which shows that the thioether bond substitution strategy is an easy yet viable way for designing high-performance electron acceptors.

Unraveling the Morphology in Solution-Processed Pseudo-Bilayer Planar Heterojunction Organic Solar Cells.

The conventional bulk heterojunction (BHJ) structure is widely used for fabricating high-performance organic solar cells (OSCs) due to the nanometer-scale phase separation of the donor/acceptor component. However, the elaborate control of the BHJ morphology is difficult to carry out because the morphology evolution is such a complicated process. The compatibility requirement of materials in the same solvent restricts the structural diversity of the molecules to some extent. Meanwhile, the nanoscopic interpenetrating donor/acceptor domains reduce their crystallinity. The bilayer planar heterojunction (PHJ), by contrast, possesses complementary advantages that can make it an alternative candidate to achieve device fabrication and produce different vertical stratification in heterojunction films. However, the flat contact area limits the charge separation and transmission efficiency. The sequential solution processed approach was used to facilitate material diffusion in layers. Also, solvent additives were employed to further enhance the diffusion and thus the device performance. Nevertheless, the morphology of the formed pseudo-bilayer planar heterojunction (PPHJ) has not been fully revealed yet. Here, we carefully study the morphology of the nonfullerene-based PPHJ device in three dimensions. High hole mobility of 2.09 × 10-4 cm2 V-1 s-1 and electron mobility of 7.91 × 10-5 cm2 V-1 s-1 were obtained in the solution-processed PPHJ device. Meanwhile, a distinct phase separation size with a vertical rearrangement of donor and acceptor was observed, which enable the pseudo-bilayer devices to be equipped with a comparable spectral response to the BHJ devices. We demonstrate that a unique device architecture (ITO/ZnO/PBDB-T/ITIC/MoO3/Ag) with a power conversion efficiency of 7% can be obtained from a larger molecular weight of PBDB-T without using extra additives. The solution-processed PPHJ films have much in common with the BHJ films. The results proposed that with appropriate molecular design and vertical phase separation optimization, the performance of the solution-processed PPHJ-based OSCs can be further improved.

Subphthalocyanine Triimides: Solution Processable Bowl-Shaped Acceptors for Bulk Heterojunction Solar Cells.

Ten subphthalocyanine triimides (SubPcTI) with different substituents at imide sites and B atoms were designed and synthesized. These compounds with low-lying lowest unoccupied molecular orbital energy levels (from -3.91 to -3.98 eV), strong absorption in the range of 450-650 nm, and adjustable solubility are expected to be excellent electron acceptors. Non-fullerene bulk heterojunction organic solar cells based on acceptor 8c showed power conversion efficiency of 4.92%, which is the highest value among subphthalocyanine derivatives.

Seleno twisted benzodiperylenediimides: facile synthesis and excellent electron acceptors for additive-free organic solar cells.

Seleno twisted benzodiperylenediimides (TBDPDI-Se) as promising electron acceptor chromophores were designed and synthesized using a facile strategy with which different side chains could be introduced readily. Bulk heterojunction organic solar cells based on these acceptors exhibit the highest power conversion efficiency of 7.41% without any additive treatment.

Vertical Stratification Engineering for Organic Bulk-Heterojunction Devices.

High-efficiency organic solar cells (OSCs) can be produced through optimization of component molecular design, coupled with interfacial engineering and control of active layer morphology. However, vertical stratification of the bulk-heterojunction (BHJ), a spontaneous activity that occurs during the drying process, remains an intricate problem yet to be solved. Routes toward regulating the vertical separation profile and evaluating the effects on the final device should be explored to further enhance the performance of OSCs. Herein, we establish a connection between the material surface energy, absorption, and vertical stratification, which can then be linked to photovoltaic conversion characteristics. Through assessing the performance of temporary, artificial vertically stratified layers created by the sequential casting of the individual components to form a multilayered structure, optimal vertical stratification can be achieved. Adjusting the surface energy offset between the substrate results in donor and acceptor stabilization of that stratified layer. Further, a trade-off between the photocurrent generated in the visible region and the amount of donor or acceptor in close proximity to the electrode was observed. Modification of the substrate surface energy was achieved using self-assembled small molecules (SASM), which, in turn, directly impacted the polymer donor to acceptor ratio at the interface. Using three different donor polymers in conjunction with two alternative acceptors in an inverted organic solar cell architecture, the concentration of polymer donor molecules at the ITO (indium tin oxide)/BHJ interface could be increased relative to the acceptor. Appropriate selection of SASM facilitated a synchronized enhancement in external quantum efficiency and power conversion efficiencies over 10.5%.

Facile Approach to Perylenemonoimide with Short Side Chains for Nonfullerene Solar Cells.

Electron acceptors based on perylene monoimide (PMI) are rare due to the synthetic challenge. Herein, starting from commercially available perylene dianhydride, brominated perylene monoimide (PMI-Br) with short side chains and good solubility was efficiently synthesized in a high overall yield of 71%. With PMI-Br as the intermediate, acceptor-donor-acceptor type electron acceptors with low-lying LUMO energy levels and strong visible absorption were successfully obtained. The nonfullerene bulk heterojunction solar cells based on these acceptors were fabricated with the highest PCE of 1.3%.

A soluble ladder-conjugated star-shaped oligomer composed of four perylene diimide branches and a fluorene core: synthesis and properties.

A new ladder-conjugated star-shaped oligomer electron-transporting material TetraPDI-PF, with four perylene diimide (PDI) branches and a fluorene core, was efficiently synthesized. The oligomer is highly soluble in dichlorobenzene with a solubility of 155 mg mL(-1), which is higher than those of PDI (35 mg mL(-1)) and PDI-Phen (70 mg mL(-1)). Demonstrated by thermogravimetric analysis (TGA), the oligomer exhibits excellent thermal stability with the decomposition temperature (Td) of 291.2 °C, which is 65 °C higher than that of PDI. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to investigate the electrochemical properties. Although the CV curves of TetraPDI-PF are successively scanned for 15 cycles, they still remain invariable reduction potentials. The oligomer also shows outstanding photostability, even better than PDI, which maintains 99 % fluorescence intensity after irradiation for 10 min using maximum laser intensity. In the steady-state space-charge-limited current (SCLC) devices, TetraPDI-PF exhibits higher intrinsic electron mobility of 2.22×10(-5) cm(2) V(-1) s(-1), three orders of magnitude over that of PDI (3.52×10(-8) cm(2) V(-1) s(-1)). The bulk heterojunction (BHJ) organic solar cells (OSCs) using TetraPDI-PF as non-fullerene acceptors and P3HT as donors give optimum power conversion efficiency (PCE) of 0.64 %, which is 64 times that of the PDI:P3HT BHJ cells.

Liquid crystalline perylene diimide outperforming nonliquid crystalline counterpart: higher power conversion efficiencies (PCEs) in bulk heterojunction (BHJ) cells and higher electron mobility in space charge limited current (SCLC) devices.

In this work, we propose the application of liquid crystalline acceptors as a potential means to improve the performances of bulk heterojunction (BHJ) organic solar cells. LC-1, a structurally-simple perylene diimide (PDI), has been adopted as a model for thorough investigation. It exhibits a broad temperature range of liquid crystalline (LC) phase from 41 °C to 158 °C, and its LC properties have been characterized by differental scanning calorimetry (DSC), polarization optical microscopy (POM), and X-ray diffraction (XRD). The BHJ devices, using P3HT:LC-1 (1:2) as an organic photovoltaic active layer undergoing thermal annealing at 120 °C, shows an optimized efficiency of 0.94 %. By contrast, the devices based on PDI-1, a nonliquid crystalline PDI counterpart, only obtain a much lower efficiency of 0.22%. Atomic force microscopy (AFM) images confirm that the active layers composed of P3HT:LC-1 have smooth and ordered morphology. In space charge limited current (SCLC) devices fabricated via a spin-coating technique, LC-1 shows the intrinsic electron mobility of 2.85 × 10(-4) cm(2)/(V s) (at 0.3 MV/cm) which is almost 5 times that of PDI-1 (5.83 × 10(-5) cm(2)/(V s)) under the same conditions for thermal annealing at 120 °C.

Regioselective photocyclization to prepare multifunctional blocks for ladder-conjugated materials.

Multifunctional building blocks 8 and 9 were efficiently synthesized by fusing a perylene-3,4,9,10-tetracarboxylic acid bisimide (PBI) core with o-phenylenediamine, and they were condensed with a pyrenedione and a pyrenetetraone, respectively, to construct new ladder-type conjugated oligomers 12 and 13. In the key photocyclization step, an unusual regioselectivity at the position ortho to the nitro group was discovered in the coupling of the o-nitroaniline functional units at the bay sites of PBI. Bulk-heterojunction solar cells based on 12 and 13 as the acceptors exhibited reasonable performance.

Fusing three perylenebisimide branches and a truxene core into a star-shaped chromophore with strong two-photon excited fluorescence and high photostability.

A novel star-shaped chromophore, Tr-PBI, was constructed by fusing three perylenebisimide branches and a truxene core. Tr-PBI exhibits high photostability and excellent two-photon properties: the maximum of δ(TPA) is 11,000 GM at 990 nm and fluorescence quantum efficiency Φ is 0.40 in THF.

Fused perylenebisimide-carbazole: new ladder chromophores with enhanced third-order nonlinear optical activities.

A series of ladder chromophores featuring planar structures of fused perylenebisimide and carbazole have been efficiently synthesized via photocyclization under sun light. Compared to N,N'-bis(3-pentyl) perylenebisimide (PBI-1), they show remarkably enhanced nonlinear properties.

Difluoridodioxido(1,10-phenanthroline)molybdenum(VI).

The title compound, [MoF(2)O(2)(C(12)H(8)N(2))], has non-crystallographic mirror symmetry. The Mo(VI) atom shows a distorted octa-hedral environment, with the phenanthroline N atoms and the two oxide groups forming the equatorial plane and the F atoms occupying the apical positions. Weak C-H⋯O and C-H⋯F hydrogen-bonding contacts and π-π inter-actions [centroid-centroid distance = 3.662 (1) Å] connect the complex mol-ecules into a three-dimensional supra-molecular framework.

catena-Poly[[bis-(2,2'-bipyridine-κN,N')cadmium(II)]-µ-9,10-dioxo-anthracene-1,5-disulfonato-κO:O].

The title complex, [Cd(C(14)H(6)O(8)S(2))(C(10)H(8)N(2))(2)](n), exhibits a chain-like polymeric structure with 9,10-dioxoanthracene-1,5-disulfonate anions bridging Cd(II) atoms in a bis-monodentate mode. The Cd(II) atom shows a distorted octa-hedral environment, with four N atoms from two chelating 2,2'-bipyridine ligands forming the equatorial plane and two sulfonate O atoms from two 9,10-dioxoanthracene-1,5-disulfonate anions occupying the apical positions. Weak C-H⋯O hydrogen-bonding contacts and π-π inter-actions [centroid-centroid distances = 3.6920 (12) and 3.7095 (12) Å] connect the complex mol-ecules into a three-dimensional supra-molecular framework.