Junting Wang

Dithienopicenocarbazole as the kernel module of low-energy-gap organic dyes for efficient conversion of sunlight to electricity

An electron-donor with a polycyclic aromatic hydrocarbon dithieno[2′,3′:2,3;3′′,2′′:10,11]piceno[1,14,13,12-bcdefgh]carbazole (DTPC) as the primary skeleton and also decorated with multiple solubilizing groups is coupled to 4-(benzo[c][1,2,5]thiadiazol-4-ylethynyl)benzoic acid, for a metal-free organic dye (C281). The near-infrared photosensitizing dye exhibits over 80% external quantum efficiency in a broad spectral range from 480 nm to 735 nm, and a high power conversion efficiency of 13.0% under irradiance of simulated AM 1.5G sunlight (100 mW cm−2).

Theoretical studies on the properties of acid site in isomorphously substituted ZSM-5

The structure and electronic properties of the Bronsted acid site in B, Al or Ga isomorphously substituted ZSM-5 zeolites were studied by ab initio HF or DFT methods. The dependence of the calculation results on the employed methods, cluster size and basis sets was examined in details. Several measures for determining of the acidity including the proton affinity, the charge on proton, the hydroxyl group vibrational frequencies, γOH, as well as the adsorption energy of NH3 showed that the acidity of the substituted ZSM-5 increases in the sequence: B–ZSM-5<Ga–ZSM-5<Al–ZSM-5, which is in good agreement with experimental results. Studies on the interaction of NH3 with the Bronsted acid site indicated that NH3 becomes protonated in contact with the zeolite cluster and the configurations in which the protonated NH3 interacts with two lattice oxygen atoms are favored energetically. In addition, the calculated adsorption energy of NH3 on Al–ZSM-5 is comparable with the experimental data.

A Systematic Study on the Influence of Electron-Acceptors in Phenanthrocarbazole Dye-Sensitized Solar Cells

In this work, by conjugating 2-cyanoacrylic acid (CA), 4-(benzo[c][1,2,5]thiadiazol-7-yl)benzoic acid (BTBA), 4-(7-ethynylbenzo[c][1,2,5]thiadiazol-4-yl)benzoic acid (EBTBA), and 4-((7-ethynylbenzo[c][1,2,5]thiadiazol-4-yl)ethynyl)benzoic acid (EBTEBA) to a binary electron-donor diphenylamine-phenanthrocarbazole (DPA-PC), we systematically investigate the impacts of electron-acceptors upon energy level, energy gap, light-harvesting ability, photovoltaic parameter, and cell stability of donor-acceptor dyes in photoelectrochemical cells. In conjunction with an ionic liquid composite electrolyte, the DPA-PC dye with EBTEBA as electron-acceptor yields a high power conversion efficiency of 8% and an outstanding stability after a 1000 h aging test under the soaking of full sunlight at 60 °C in a dye-sensitized solar cell. Femtosecond fluorescence up-conversion measurements have suggested that energy relaxation and electron injection both occur to dye molecules in the nonequilibrium excited states. Moreover, the time constants of injecting electrons from dye molecules in the excited states to titania are very dispersive for over 1 order of magnitude, mainly owing to the broad energy distribution of excited states.

Judicious engineering of a metal-free perylene dye for high-efficiency dye sensitized solar cells: the control of excited state and charge carrier dynamics

Molecular engineering of a photosensitizing dye plays a vital role in the control of excited states and charge carriers in dye-sensitized solar cells (DSCs) for performance improvement. Herein we report three metal-free donor–acceptor organic dyes by conjugating electron donors triphenylamine–cyclopentadithiophene (TPA–CPDT), triphenylamine–phenanthrocarbazole (TPA–PC), and di(biphenyl)amine–phenanthrocarbazole (DBPA–PC) with electron acceptor 4-(7-ethynylbenzo[c][1,2,5]thiadiazol-4-yl)benzoic acid (EBTBA). The influences of electron donors on the energy levels, light absorption, dynamics of excited states and photogenerated charges, and photovoltaic parameters of DSCs were systematically analyzed via theoretical calculations and physical measurements. A DSC with dye SC-3 employing the bulky DBPA–PC electron donor achieved a high power conversion efficiency (PCE) of 11.5% measured under the air mass 1.5 global (AM1.5G) conditions, owing to the significantly reduced interfacial charge recombination. Femtosecond fluorescence upconversion measurements have unraveled that energy relaxation and electron injection both occur for dye molecules in the nonrelaxed hot excited states. Also, the rate constants of injecting electrons from dyes in the excited states to titania are very dispersive by over 1 order of magnitude, which could be mainly ascribed to the broad energy distribution of excited states.

Monte Carlo simulation of alkylation of toluene with alcohols over zeolite catalysts

Abstract A Monte Carlo model for the simulation of alkylation of toluene with alcohols over zeolite catalysts was developed. On the basis of the experimentally observed parameters, including the intracrystalline diffusivity, equilibrium adsorption constant, and intrinsic rate constant, the alkylations of toluene with methanol and ethanol were simulated. The results were in good agreement with those of the experiments. This suggests that the Monte Carlo method is helpful for investigating the nature of shape selectivity in zeolite-catalyzed reactions.

Monte Carlo simulation of xylene isomerization over zeolite catalysts

The isomerization reaction of xylene was simulated by means of the Monte Carlo method based on the experimentally observed parameters, including the diffusivity, equilibrium adsorption constant and intrinsic rate constant. The dependence of the product selectivity upon the Thiele modulus was examined and the results were satisfactorily consistent with those of the continuous model as well as the experiments. This suggests that the Monte Carlo method is helpful for investigating the nature of shape selectivity in zeolite-catalyzed reactions.

A Perylene-Based Polycyclic Aromatic Hydrocarbon Electron Donor for a Highly Efficient Solar Cell Dye.

The continuing efforts to develop novel polycyclic aromatic hydrocarbons and exploit them as building blocks to create organic donor-acceptor (D-A) dyes with impressive excited-state features should offer an excellent means by which to improve the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). To this end, a nonacyclic aromatic hydrocarbon, N-annulated benzoindenopentaphene (NBIP) was tethered with multiple solubilizing groups, including NBIPs with one 2-hexyldecyl, with one 2-hexyldecyloxy, and with four 4-hexylphenyl substituents. The side- and end-chain-functionalized NBIPs can be conveniently prepared in excellent yield, and further cross-coupled with 4-(7-ethynylbenzo[c][1,2,5]thiadiazol-4-yl)benzoic acid to afford a metal-free D-A dye, which achieves a high power conversion efficiency of 12.6 % under AM1.5G illumination in DSSCs without need for any coadsorbent.

Monte Carlo simulation of effects of pore entrance deactivation on reaction performance

The complex isomerization A=B=C over zeolites is simulated using a Monte Carlo method which accounts for the elementary processes of adsorption, diffusion, reaction and desorption. The effects of pore entrance deactivation on the product selectivity and effectiveness are investigated, and the results show that the shape selectivity in zeolites-catalyzed reactions can be enhanced by pore entrance deactivation as the reaction is operated in diffusion-controled region.

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. This work demonstrates the significant influence of lateral substituents of HTMs on the intermolecular packing and solid microstructure, giving a clear insight on the molecular design of high-performance organic semiconductors.