Min Huang

Palladium-catalyzed cross-coupling reactions of 4a,8a-azaboranaphthalene.

A concise and effective three-step synthesis of 4a,8a-azaboranaphthalene (ABN) has been developed in gram scale. Electrophilic aromatic substitution reactions of ABN provide excellent functional-group-tolerant cross-coupling partners in various Pd-catalyzed cross-coupling reactions (e.g., Sonogashira, Suzuki-Miyaura, or Heck reaction). Photophysical, electrochemical, and DFT calculations all suggest a narrowed HOMO-LUMO gap with extended π-conjugation characters in the cross-coupled molecules. The ABN moiety as a new fluorophore has a distinct and selective fluorescence response toward Zn(II) and Cd(II) ions, demonstrating great potential for the ABN structural motif in fluorescent chemosensors.

Investigation of an upflow cold-wall CVD reactor by gas phase Raman spectroscopy

The gas phase dynamics of an inverted, stagnation point flow CVD reactor were studied by both experiment and modeling. The axial centerline temperature profile in the reactor was measured by analysis of the rotational Raman spectra from the carrier gas ( No r H) as a function of the inlet flow velocity and the reactor aspect ratio.It was found that a larger temperature gradient 22 normal to the susceptor surface was obtained with higher gas flow velocity, larger aspect ratio, and the use of a N carrier gas. 2 A two-dimensional axisymmetric model with detailed heat transfer descriptions predicted the experimental data well.The validated model clearly demonstrates that recirculation flows are less likely in inverted reactor geometry. 2002 Elsevier Science B.V. All rights reserved.

4a,8a-Azaboranaphthalene-4-yl phosphine ligands: synthesis and electronic modulation in Suzuki–Miyaura coupling reactions

The preparation of a new class of triarylphosphine ligands consisting of the 4a,8a-azaboranapthalene-4-yl (ABN) group is disclosed. X-ray analysis and DFT calculations demonstrate a characteristic π-conjugation system of ABN-phosphine 3, which has been evaluated as a supporting ligand in Pd-catalysed Suzuki–Miyaura coupling reactions of aryl halides and phenyl boronic acid.

Numerical Procedure to Extract Physical Properties from Raman Scattering Data in a Flow Reactor

School of Chemical Engineering and Technology, Yeungnam University, Gyeongsan 712-749,Republic of KoreaA parameter estimation procedure was established to extract physical parameters related to chemical vapor deposition ~CVD!processes, which consists of in situ experimental data collection and computational analysis. Specifically, mass-transport behaviorin an up-flow cold-wall CVD reactor was monitored usingin situ Raman spectroscopy. A two-dimensional axisymmetric model ofthe reactor was developed and combined with genetic and simplex algorithms for property estimation. The numerical procedurewas unambiguously able to extract binary mass diffusivities and Raman cross sections from the same data set for the methane/nitrogen and ammonia/nitrogen cases. The procedure developed in this study is general and expected to be particularly useful inextracting diffusivities and cross sections for reaction intermediate species and kinetic parameters for complex reacting systems.© 2005 The Electrochemical Society. @DOI: 10.1149/1.1885366# All rights reserved.Manuscript received March 2, 2004. Available electronically April 18, 2005.

Multiscale study of the formation of the PFI:PSS:PEDOT super structure and its HOMO-LUMO energies

The vertically self-organized concentration profile of the PSS:PEDOT:PFI layer from mesoscale DPD simulations presented in the previous contribution were inversely mapped back into atomistic scale. DFT quantum calculations were then performed to understand the nature of the formation of the PFI:PSS:PEDOT complex. Hydrogen bond bonding energy and deprotonation energy were obtained accordingly. The charge states of PSS polymer chain in this complex and its effects on the HOMO-LUMO (the work function) were discussed. The DFT quantum calculation revealed the formation of complex hydrogen bonding networks leading to the formation of super PFI:PSS:PEDOT structure. PFI was found to be a stronger H donor than PSS. The adding of PFI was found to have the effect of lowering the energy of PSS chain, as the result the HOMO of the PFI:PSS:PEDOT ternary structure was found to be -5.35 eV, lower than the original PSS:PEDOT binary structure. The increasing of the work function from the bottom to the top of the film can therefore be understood as the result of the combining effects of increasing PSS:PEDOT and PFI:PSS ratio in the vertical direction induced by PFI led phase segregation.

Study of the interaction of PSS-PEDOT, PCBM and Sprio-OMeTAD with MAPbI3 crystal facets using molecular dynamics simulation

The role of MAPbI3 perovskite crystal facet surface property, surface cohesion, was investigated in this study. The interaction energy of as grown MAPbI3 perovskite crystal facet (002), (110), (112) and (200) with organic PSS-PEDOT, PCBM and Sprio-OMeTAD molecules were obtained using molecular dynamics simulations. The results indicated that these three molecules can interact well with all four common facets of MAPbI3 crystal producing negative interactive energies. The interacting between Sprio-OMeTAD molecule and the MAPbI3 perovskite crystal surface is the strongest producing the lowest interactive energy. While PCBM is the weakest and PSS-PEDOT in between. The interaction energies of these three molecules show similar preferential orders, they are (112), (002), (200) and (110) respectively. In the PCBM case, energy differences among facet surfaces (002), (110) and (200) are small when compare with surface (112). Solar cells made from tailored crystals with large (112)/(002) surfaces can be expected to have better crystal-PEDPT:PSS contact therefore, better hole injection efficiency. Same goes to the Sprio-OMeTAD and PCBM where higher electron extraction efficiency can be expected.

Multiscale study of the Self-Organized Gradient Effect of Novel Hole Injection Material PEDOT:PSS:PFI

Conducting polymers, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been widely used as the hole injection layer (HIL) in many applications. However, in OLEDs the commonly used PEDOT:PSS has been found to have serious problems due to its inefficient holeinjection, inefficient electron-blocking, and substantial quenching of excitons close to the PEDOT:PSS. In the literature, tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octene-sulfonic acid copolymer, one of perfluorinated ionomers (PFI), was introduced into the PEDOT:PSS layer to develop a gradient work function (WF) by self-organization of the PFI. In this contribution, the self-organized gradient effect of this novel PEDOT:PSS:PFI layer were studied using multiscale analysis and dissipative particle dynamics (DPD) simulation. The DPD inter particle repulsion parameters and intramolecular bonding parameters were obtained by reverse mapping of a series of molecular dynamics simulations similar to that used in the earlier contributions. The calculated Flory-Huggins parameters indicated that the Nafion portion of the copolymer attracts PSS while the entire PFI molecule repulses PEDOT, which results in a PFI rich interface and a vertical gradient concentration distribution of PEDOT along the vertical direction of the film layer.

Multiscale analysis of the effect of micro-phase separation on the charge transfer at the PEDOT:PSS and P3HT:PCBM layer interface

The influence of micro phase behavior on the charge transfer at the interface between PEDOT:PSS and P3HT:PCBM layers was studied using multiscale analysis. Calculated Flory- Huggins parameters indicated that the PEDOT attracts P3HT and repulses PCBM that agrees well with the experimental observation of the development of P3HT rich interface during the BHJ layer formation. Based on the calculated Flory-Huggins parameters, mesoscale DPD simulations were conducted for PEDOT:PSS and P3HT:PCBM layers. Results were mapped to the CG (coarse grained) and then atomistic scales where atomistic details of the interface were studied. The density of nonbonding close contacts including that from reorientation between PEDOT and P3HT was quantified, vibronic coupling and carrier transfer efficiency were discussed.

Multiscale study of the effect of solvent on the glass transition temperature, molecule diffusion, and reorientation of P3HT-PCBM

Exciton transport plays an important role in the overall exciton dissociation process and must be optimized to yield high efficient OPV device. In this contribution, the influence of solvents and the nanoscale phase separations they caused on the glass transition temperatures (Tg) of P3HT-PCBM mixture were studied by reverse mapping mesoscale simulation results back to the molecular dynamics. Glass transition temperatures of P3HT-PCBM without solvent and with chloroform, dichlorobenzene, and chlorobenzene were obtained. Diffusion and reorientation ability of molecules and their subgroups at the temperature near Tg were also discussed.

Multiscale analysis of effect of solvents on the P3HT-PCBM active layer

Solvents are often used in the active layer formation process in many photonic applications such as organic solar cell, organic led, organic wavelength conversion and photorefractive materials. In this contribution, multiscale modeling and simulation was used to reveal phase separation in P3HT-PCBM at mesoscale level due to attractionrepulsion between different organic functional groups of active ingredient molecules and solvent molecules. Force field parameters for mesoscale calculation were obtained from dynamic mapping of results from molecular dynamic simulations. DFT calculation was used to describe energy changes of active ingredient molecules due to surrounded residual solvent molecules. The simulation results from no solvent, chloroform, dichlorobenzene and chlorobenzene cases indicated that chlorobenzene exhibits strong attraction with fullerene of PCBM and strong repulsion with all the other functional groups, therefore leads to least phase segregation. DFT calculation showed that residual solvent molecules can slightly lower the energy but do not alter the value of band gap.