Polo-like kinase 4 promotes tumorigenesis and glucose metabolism in glioma by activating AKT1 signaling.

Glioblastoma (GBM) is an extremely aggressive tumor associated with a poor prognosis that impacts the central nervous system. Increasing evidence suggests an inherent association between glucose metabolism dysregulation and the aggression of GBM. Polo-like kinase 4 (PLK4), a highly conserved serine/threonine protein kinase, was found to relate to glioma progression and unfavorable prognosis.

Incorporation of a Boron-Nitrogen Covalent Bond Improves the Charge-Transport and Charge-Transfer Characteristics of Organoboron Small-Molecule Acceptors for Organic Solar Cells.

An organoboron small-molecular acceptor (OSMA) M containing a boron-nitrogen coordination bond (B←N) exhibits good light absorption in organic solar cells (OSCs). In this work, based on M, OSMA M, with the incorporation of a boron-nitrogen covalent bond (B-N), was designed. We have systematically investigated the charge-transport properties and interfacial charge-transfer characteristics of M, along with M, using the density functional theory (DFT) and the time-dependent density functional theory (TD-DFT).

Atomistic Mechanism of Surface-Defect Passivation: Toward Stable and Efficient Perovskite Solar Cells.

Molecular engineering has been demonstrated to be a predominant strategy for augmenting the long-term stability and passivating adverse defects for perovskite solar cells (PSCs). Here, using density functional theory calculations combined with molecular dynamics (AIMD) simulations, the passivation effects of bidentate passivation molecules, and , on the iodine vacancy MAPbI were comprehensively investigated. We demonstrate that engenders stronger adsorption and localized charges on Pb atoms because the separated binding sites match with the MAPbI lattice.

Theoretical insights into photo-induced isomerization mechanisms of phenylsulfinyl radical PhSO˙.

Sulfinyl radicals (R-SO˙) play important roles in lots of reactions, while the isomer oxathiyl radicals (R-OS˙) and the isomerization between them are rarely observed due to the poor stability of R-OS˙. In this work, the complete active space self-consistent field (CASSCF) and its multi-state second order perturbation (MS-CASPT2) methods were employed to study the photo-induced reaction mechanisms of phenylsulfinyl radical PhSO˙ 1 and its isomer phenoxathiyl radical PhOS˙ 2. Our results show that 1 and 2 have similar singly occupied molecular orbitals in the ground state but different properties in the excited state, which determine their diverse behaviors after irradiation.

A π-extended triphenylamine based dopant-free hole-transporting material for perovskite solar cells heteroatom substitution.

The triphenylamine (TPA) group is an important molecular fragment that has been widely used to design efficient hole-transporting materials (HTMs). However, the applicability of triphenylamine derived HTMs that exhibit low hole mobility and conductivity in commercial perovskite solar cells (PSCs) has been limited. To aid in the development of highly desirable TPA-based HTMs, we utilized a combination of density functional theory (DFT) and Marcus electron transfer theory to investigate the effect of heteroatoms, including boron, carbon, nitrogen, oxygen, silicon, phosphorus, sulfur, germanium, arsenic, and selenium atoms, on the energy levels, optical properties, hole mobility, and interfacial charge transfer behaviors of a series of HTMs.

Theoretical Study of Non-Fullerene Acceptors Using End-Capped Groups with Different Electron-Withdrawing Abilities toward Efficient Organic Solar Cells.

Acceptors in organic solar cells (OSCs) are of paramount importance. On the basis of the well-known non-fullerene acceptor Y6, six acceptors (Y6-COH, Y6-COOH, Y6-CN, Y6-SOH, Y6-CF, and Y6-NO) were designed by end-capped manipulation. The effects of end-capped engineering on electronic properties, optical properties, and interfacial charge-transfer states were systematically studied by density functional theory, time-dependent density functional theory, and molecular dynamics.

Theoretical design of asymmetric A-DA'D-A type non-fullerene acceptors for organic solar cells.

The acceptor in organic solar cells (OSCs) is of paramount importance for achieving a high photovoltaic performance. Based on the well-known non-fullerene acceptor Y6, we designed a set of asymmetric A-D1A'D2-A type new acceptors Y6-C, Y6-N, Y6-O, Y6-Se, and Y6-Si by substituting the two S atoms of one thieno[3,2-b]thiophene unit with C, N, O, Se, and Si atoms, respectively. The electronic, optical, and crystal properties of Y6 and the designed acceptors, as well as the interfacial charge-transfer (CT) mechanisms between the donor PM6 and the investigated acceptors have been systematically studied.

Theoretical study on the photochemistry of furoylazides: Curtius rearrangement and subsequent reactions.

Organic azides are an efficient source of nitrenes, which serve as vigorous intermediates in many useful organic reactions. In this work, the complete active space self-consistent field (CASSCF) and its second-order perturbation (CASPT2) methods were employed to study the photochemistry of 2-furoylazide 1 and 3-furoylazide 5, including the Curtius rearrangement to two furylisocyanates (3 and 7) and subsequent reactions to the final product cyanoacrolein 9. Our calculations show that the photoinduced Curtius rearrangement of the two furoylazides takes place through similar stepwise mechanisms via two bistable furoylnitrenes 2 and 6.

End-capped group manipulation of indacenodithienothiophene-based non-fullerene small molecule acceptors for efficient organic solar cells.

As the key component of organic solar cells (OSCs), the acceptor plays key roles in determining the power conversion efficiency (PCE). Based on the famous non-fullerene acceptor ITIC, a series of acceptors (A1-A5) were designed by introducing fused-ring units (phenanthrene, pyrene, benzopyrazine, dibenzo[a,c]phenazine, and phenanthro[4,5-abc]phenazine) as the end groups. Theoretical calculations showed that A1-A5 display improved solubility and redshifted absorption spectra compared with ITIC.

Molecular Engineering of Hexaazatriphenylene Derivatives toward More Efficient Electron-Transporting Materials for Inverted Perovskite Solar Cells.

The electron-transporting material (ETM) in inverted perovskite solar cells (PSCs) plays important role in reducing hysteresis and realizing simple processing procedures, while the improvement of power conversion efficiency is limited by low electron mobility and weak perovskite/ETM interface interaction. In this work, three new ETMs (HAT-1, HAT-2, and HAT-3) were designed by introducing methoxyphenyl, imide, and naphthalene groups into the hexaazatriphenylene (HAT) skeleton, based on the ETM HATNASOC7 synthesized experimentally [Jen; 2016, 55, 8999]. Theoretical calculations showed that the electron mobilities of HAT-1, HAT-2, and HAT-3 are 2.

Designing Hole Transport Materials with High Hole Mobility and Outstanding Interface Properties for Perovskite Solar Cells.

Organic-inorganic halide perovskite solar cells (PSCs) have attracted much attention due to their rapid increase in power conversion efficiencies (PCEs), and many efforts are devoted to further improving the PCEs. Designing highly efficient hole transport materials (HTMs) for PSCs may be one of the effective ways. Herein we theoretically designed three new HTMs (FDT-N, FDT-O, and FDT-S) by introducing a nitrogen-phenyl group, an oxygen atom, and a sulfur atom into the spiro core of an experimentally synthesized HTM (FDT), respectively.

Understanding the effects of the co-sensitizing ratio on the surface potential, electron injection efficiency, and Förster resonance energy transfer.

Multiple absorbers that function in different absorption regions (near infra-red (NIR) and UV-Visible (UV-Vis)) have been widely used in solar cell applications to enhance the light-harvesting. Herein, two special co-sensitizing Models 1 and 2, which feature either saturated dye IQ21 or saturated co-sensitizer S2, have been added to a TiO surface to explore the effect of the altered sensitizing sequence, namely the co-sensitizing ratio of IQ21/S2 and S2/IQ21 on the electrostatic potential variation (ΔV), electron injection efficiency (η'), and Förster resonance energy transfer (FRET), using density functional theory and first-principle molecular dynamics simulations. The ΔV related to the open-circuit voltage (V) is insensitive in both Models 1 and 2.

Coconut-based activated carbon fibers for efficient adsorption of various organic dyes.

In this study, using coconut fibers as raw material, activated carbon fibers were prepared carbonization and KOH activation processes. The morphology, composition, specific surface area, pore structure and thermal stability of the resulting activated carbon fibers were systematically characterized. It was found that the activation process increases the specific surface area of carbon fibers to a greater extent formation of a large number of micropores (0.

A peri-Xanthenoxanthene Centered Columnar-Stacking Organic Semiconductor for Efficient, Photothermally Stable Perovskite Solar Cells.

Modulating the structure and property of hole-transporting organic semiconductors is of paramount importance for high-efficiency and stable perovskite solar cells (PSCs). This work reports a low-cost peri-xanthenoxanthene based small-molecule P1, which is prepared at a total yield of 82 % using a three-step synthetic route from the low-cost starting material 2-naphthol. P1 molecules stack in one-dimensional columnar arrangement characteristic of strong intermolecular π-π interactions, contributing to the formation of a solution-processed, semicrystalline thin-film exhibiting one order of magnitude higher hole mobility than the amorphous one based on the state-of-the art hole-transporter, 2,2-7,7-tetrakis(N,N'-di-paramethoxy-phenylamine 9,9'-spirobifluorene (spiro-OMeTAD).

Nitrogen substitution improves the mobility and stability of electron transport materials for inverted perovskite solar cells.

A suitable electron transport material (ETM) plays key roles in efficient perovskite solar cells (PSCs), because it is beneficial for exciton dissociation and charge transport at the interface thus increasing the short circuit current density. Based on the experimentally reported efficient electron transport molecule 10,14-bis(5-(2-ethylhexyl)thiophen-2-yl)-dipyrido[3,2-a:2',3'-c][1,2,5]thiadiazolo[3,4-i]phenazine (TDTP), we theoretically design a set of new ETMs (TDTP-1, TDTP-2a, TDTP-2b, TDTP-3a, and TDTP-3b) by introducing a nitrogen atom into the thiophene ring or replacing a hydrogen atom on the methyl with an amino group. Quantum-chemical calculations reveal that the designed molecules behave much better than TDTP in terms of electron mobility, air stability, and solubility, where the electron mobility of TDTP-3b is two orders of magnitude higher than that of TDTP owing to the extra SN interactions in TDTP-3b that lead to the quasi two-dimensional π packing motif which facilitates electron transport evidently.

Effect of π-bridge units on properties of A-π-D-π-A-type nonfullerene acceptors for organic solar cells.

Acceptor-π-donor-π-acceptor (A-π-D-π-A)-types of small molecules are very promising nonfullerene acceptors to overcome the drawbacks of fullerene derivatives such as the weak absorption ability and electronic adjustability. However, only few attempts have been made to develop π-bridge units to construct highly efficient acceptors in OSCs. Herein, taking the reported acceptor P1 as a reference, five small-structured acceptors (P2, P3, P4, P5, and P6) have been designed via the replacement of the π-bridge unit.

N-Annulated Perylene-Based Hole Transporters for Perovskite Solar Cells: The Significant Influence of Lateral Substituents.

Perylene derivatives are a family of well-known organic electron-transporting materials with excellent photochemical and thermal stabilities, and have been widely used in various optoelectronic devices. In this work, two diphenylamine functionalized N-annulated perylenes are reported as hole-transporting materials (HTMs) for perovskite solar cells. Through joint theoretical and experimental studies, the HTM employing a methoxyphenyl lateral substituent is found to feature a closer stacking distance and better aggregate connectivity in the solid film than its analogue with the bulky 2-hexyldecyl lateral substituent, contributing to a higher hole mobility and a remarkably enhanced device performance of perovskite solar cells.

The electron injection rate in CdSe quantum dot sensitized solar cells: from a bifunctional linker and zinc oxide morphology.

Herein, we have investigated the effect of both the bifunctional linker (L1, L2, L3, and L4) and ZnO morphology (porous nanoparticles (NPs), nanowires (NWs), and nanotubes (NTs-A and NTs-Z)) on the electron injection in CdSe QD sensitized solar cells by first-principles simulation. Via calculating the partitioned interfaces formed by different components (linker/QDs and ZnO/linker), we found that the electronic states of QDs and every ZnO substrate are insensitive to any linker, while the frontier orbitals of L1-L4 (with increased delocalization) manifest a systematical negative-shift. Because of the lowest unoccupied molecular orbital (LUMO) of L1 compared to its counterparts aligned in the region of the virtual states of QDs or the substrate with a high density of states, it always yields a stronger electronic coupling with QDs and varied substrates.

Effect of Water on the Structure and Stability of Hydrogen-Bonded Oxalic Acid Dimer.

As the simplest and most abundant dicarboxylic acid in the atmosphere, oxalic acid (OA) not only plays a key role in aerosol nucleation, but also acts as a prototypical compound for the investigation of intra- and intermolecular hydrogen-bonding interactions. A systematic theoretical study on the hydrated OA dimers performed by using DFT at the M06-2X/6-311++G(3df, 2p) level is discussed herein. The properties of hydrogen bonds in clusters are inspected through topological analysis by using atoms in molecules (AIM) theory.

Extending donor size in D-A-π-A organic dye for dye sensitized solar cells: Anti-aggregation and improving electron injection.

We have theoretically designed two D-A-π-A dyes 3 and 4 based on the efficient references 1 and 2 by introducing an extra electron donor unit (D2). Via calculating the electronic structures of isolated dyes, we obtain that dyes 3 and 4 possess stronger light-harvesting efficiency imparted by the fluorescence energy transfer of D2 part, maintain comparable lifetime of excited states, and shorten the electron injection time significantly with regard to 1 and 2. Meanwhile, dye 3 positively shifts the edge of virtual states of TiO in a larger extent compared to its counterparts.

Novel benzodithiophene-based polymer acceptors for efficient organic solar cells.

All polymer organic solar cells afford unique potentials due to the tunable chemical and electronic properties of both polymer donors and polymer acceptors. Compared with the rapid development of polymer donors, the development of polymer acceptors lags far behind. To seek high-performance polymer acceptors used in organic solar cells, based on the experimentally reported D-A polymer acceptor (NDI2OD-T2) (P1), a series of novel acceptors, designated as (BDTNDI2OD-T2)(P2), (BDTNDTI)(P3), (BDTNDI2OD-Tz2)(P4), and (BDTNDTzI)(P5), were designed by introduction of a benzodithiophene (BDT) unit and the nitrogen atom in the bridged thiophene ring.

Strategy for designing stable and powerful nitrogen-rich high-energy materials by introducing boron atoms.

One of the most important aims in the development of high-energy materials is to improve their stability and thus ensure that they are safe to manufacture and transport. In this work, we theoretically investigated open-chain NB isomers using density functional theory in order to find the best way of stabilizing nitrogen-rich molecules. The results show that the boron atoms in these isomers are aligned linearly with their neighboring atoms, which facilitates close packing in the crystals of these materials.

Insights into the Thermal Eliminations and Photoeliminations of B,N-Heterocycles: A Theoretical Study.

Understanding the photochemistry of organoboron compounds is essential to expand optoelectronic applications. In this work, the complete active space self-consistent field (CASSCF) and its second-order perturbation (CASPT2) methods combining with density functional theory (DFT) have been employed to investigate the elimination mechanisms of compound 6,7-dihydro-5-benzo[d]pyrido[2,1-f][1,2]azaborininr (B4) on the ground state (S) and the first excited state (S). B4 is one of the 1,2-B,N-heterocycles that undergo competitive thermal elimination and photoelimination depending on the substitution groups on the B atom and the chelate backbone, thus providing a high-selectivity synthesis strategy for luminescent compounds.