Benzothiadiazole Containing D‐π‐A Conjugated Compounds for Dye‐Sensitized Solar Cells: Synthesis,Properties, and Photovoltaic Performances

Two D ‐π‐A conjugated molecules, BzTCA and BzTMCA , were developed through facile synthetic approaches for dye‐sensitized solar cells. The investigation of the photophysical properties of BzTCA and BzTMCA both in dilute solutions and in thin films indicates that their absorption exhibits a wide coverage of the solar spectrum. The absorption features for BzTCA and BzTMCA commence at about 710 nm in solution, and at about 800 nm in the solid state. The absorption maxima (λ_max) for both BzTCA and BzTMCA on TiO₂ film are almost the same as those in dilute solution. Their HOMOs and LUMOs were found to partly overlap at the center of these dyes, which guarantees appreciable interactions between the donors and acceptors. The investigation of the performance of dye‐sensitized solar cells fabricated from BzTCA and BzTMCA indicated that the power‐conversion efficiencies are 6.04 % and 4.68 %, respectively, which could be comparable with the normal sensitizer N3. BzTMCA showed lower incident photon‐to‐electron conversion efficiency (IPCE) and J_sc values relative to BzTCA , which is probably because of the weaker driving force of dye regeneration and electron injection process of BzTMCA . The IPCE responsive area reached nearly 800 nm, which provides great potential for further improvement of the photocurrent density and power‐conversion efficiency. Our investigations demonstrate that both dyes BzTCA and BzTMCA could be promising candidates for dye‐sensitized solar cells.     

Excited-state intramolecular proton transfer in 2-(2′,6′-dihydroxyphenyl)benzoxazole: effect of dual hydrogen bonding on the optical properties

2-(2′,6′-Dihydroxyphenyl)benzoxazole (DHBO) has been synthesized by using palladium-catalyzed oxidative cyclization. The compound utilizes both O-H···N and O-H···O bonds to ensure a coplanar structure between the benzoxazole and phenol fragments. Optical comparison with the parent compound 2-(2′-hydroxyphenyl)benzoxazole (HBO) reveals that the dual hydrogen bonding in DHBO plays an essential role in raising the desirable keto emission for ESIPT and tuning the polarity sensitivity toward the molecular environment. DHBO also exhibits a higher quantum yield (?_fl = 0.108 in methanol) than HBO (?_fl = 0.0025) in the same solvent.     

磺化聚芳醚酮砜/聚吡咯复合型直接甲醇燃料电池用质子交换膜的制备与性能研究

以高磺化度的磺化聚芳醚酮砜(SPAEKS)和吡咯(Py)为原料,通过原位聚合的方法制备了含有不同吡咯含量的SPAEKS/PPy复合膜.红外谱图表明SPAEKS聚合物中的磺酸基团与聚吡咯(PPy)中的亚氨基基团之间形成了强烈的相互作用.扫描电镜照片显示PPy能够均匀地分散在SPAEKS聚合物基体中,没有发生团聚现象.通过对复合膜的性能测试发现PPy的引入提高了复合膜的热稳定性,降低了复合膜的吸水率,改善了其水溶胀性.同时膜中水的脱附系数下降,提高了膜的保水能力.SPAEKS/PPy-3复合膜的甲醇渗透系数达到了1.18×10-7cm2/s,明显低于纯SPAEKS膜的8.52×10-7cm2/s,而其质子传导率虽有所降低,但在25℃和80℃仍然分别达到了0.039S/cm和0.061S/cm,能够满足质子交换膜对质子传导率的要求.研究结果表明,聚吡咯与SPAEKS中磺酸基的摩尔比为0.99的复合膜有望在直接甲醇燃料电池中得到应用.     

Symmetry breaking,diradicals, and Coping with and Coping without Ernest Davidson

This paper describes a collaboration between Professor Ernest Davidson and the author, which began in 1976 and lasted until Ernest left the University of Washington in 1984. During those 9 years we co-authored a total of 34 papers that described the results of ab initio calculations on a variety of different types of organic molecules, These included anti-aromatic annulenes, carbanions, carbenes, conjugated radicals and radical cations, and non-Keklé hydrocarbon diradicals. Our collaboration led to insights about symmetry breaking, both real and artefactual, which formed the basis for a frequently-cited review article on this subject that we co-authored. However, our most often-referenced paper was concerned with predicting the sizes and signs of the singlet-triplet splittings in diradicals, based on whether or not the non-bonding Hückel molecular orbitals of a diradical can be chosen so that they are confined to disjoint sets of atoms. In 1984, we co-authored a paper on the Cope rearrangement. Since then, we have both continued to publish papers on this interesting reaction, but independently, rather than together. The results of the calculations that we each performed on the Cope rearrangement and how this reaction is affected by radical-stabilizing substituents are described. Our independent discoveries, that calculations beyond the CASSCF level are necessary in order to describe correctly the transition structure for the Cope rearrangement, led to our most recent joint publication, a 1996 review on the general importance of including dynamic correlation in ab initio calculations.     

Stereoelectronic effects and the problem of the choice of model compounds for organic derivatives of a pentacoordinated silicon atom (taking silatranes as an example)

Anomeric effects at the silicon atom in silatranes XSi(OCH₂CH₂)₃N and model trimethoxysilanes XSi(OMe)₃ (X=H, Me, SiH₃, F, Cl) containing a tetracoordinated silicon atom were studied by the MNDO and AM1 methods. Unlike silatranes, the nature of substituent X pronouncedly affects the type and degree of stereoelectronic effects on the values of X−Si−O−C dihedral angles, X−Si bond lengths, and proton affinities of trimethoxysilanes. The results obtained indicate the necessity of modifying the set of spectral and structural indications of pentacoordination of the anomeric silicon atom established previously and observing the principle of conformational similarity for compared compounds. Bicyclic organosilicon ethers XSi(OCH₂)₃CH were proposed to be used as models of corresponding silatranes. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1061–1065, June, 1999.     

Luminous, fully aliphatic polyamides: Multicolor photoluminescence, their pH and solvent dependency

Novel luminous aliphatic polyamides were obtained from a condensation reaction of ethylene diamines and malonyl dichloride in the presence of triethylamine. These polymers appeared in blackish red and reddish orange solids and unusually exhibited a visible light-emission. Their fluorescence properties were significantly dependent on the excitation wavelength, media polarity, and acidity. These polymers emitted fairly strong visible lights in a wide range from blue to near yellow when excited at wavelengths longer than 305 nm. The emission bands significantly shifted to longer wavelengths during the increase in the polarity of the solvent used. Their fluorescence intensities significantly increased under acidic conditions.     

Elastic recoil detection analysis (ERDA) in hydrogenated samples for TNSA laser irradiation

This paper provides an overview of theory, method, and examples concerning the elastic recoil detection analysis employed in forward recoil spectrometry to monitor the hydrogen content of hydrogenated targets prepared to be irradiated by high‐intensity lasers in target normal sheath acceleration regime. Polymers, semiconductors, and ‘advanced foils’ were analyzed to evaluate their hydrogen content as potential source for plasma proton acceleration. Helium ions at 2.0 MeV were employed as a target probe in a glancing angle to induce recoil hydrogen atoms and to measure the hydrogen concentration in the first superficial layers of the target. Results demonstrated that the hydrogen degassing occurs under ion beam irradiation, that its content depends on the polymer specie and porosity, that it is possible to control thin hydrogenated film thickness, and that the technique has sufficient isotope resolution to separate hydrogen from deuterium content. Copyright © 2015 John Wiley & Sons, Ltd.     

Combinatorial approach for fast screening of functional materials

We present an integrated system with automated sample fabrication for combinatorial investigations of solution-processed organic materials. To illustrate the applicability of the system, we give examples of typical experimental results with organic electronic devices. Organic light emitting diodes (OLEDs) based on a poly-(N-vinylcarbazole) matrix system with small molecule hole-transporter N,N′-Bis(3-methylphenyl)-N,N′-diphenyl-benzidine (TPD) and electron transporter 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) were optimized. In a single experimental run, the optimum range of TPD and PBD concentrations has been determined. Furthermore, we screened the influence of a gate dielectric modification with poly(methyl silsesquioxane) in organic field effect transistors and show that the choice of the material system, which constitutes the interface between the gate dielectric and the organic semiconductor, modulates the mobility of the field-effect device by more than two orders of magnitude. Finally, we present a combinatorial study of the influence of PEDOT-PSS and P3HT-PC₆₁BM layer thickness variation in organic photo voltaic cells. To summarize, we describe the possibilities of a combinatorial tool for solution based multilayer devices comprising functional materials. The tool is applicable to a vast variety of such materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1587–1593, 2010