Synthesis and photovoltaic properties of two side‐chain polymeric metal complexes containing 8‐hydroxyquinoline and fluorene units with Zn(II) and Cd(II)

Two novel side‐chain polymeric metal complexes (PF1 and PF2) containing 8‐hydroxyquinoline and fluorene units with Zn(II) and Cd(II) having donor‐acceptor π‐conjugated structure have been synthesized and characterized using Fourier transform infrared, ¹H NMR, UV‐visible and photoluminescence spectroscopies, thermogravimetric analysis, differential scanning calorimetry, elemental analysis and cyclic voltammetry. Dye‐sensitized solar cells (DSSCs) based on PF1 and PF2 as the dye sensitizers exhibit good device performance with solar‐to‐electricity conversion efficiency up to 0.32% (J_sc = 0.83 mA cm^?2, V_oc = 0.62 mV and FF = 0.62) and 0.24% (J_sc = 0.69 mA cm^?2, V_oc = 0.59 mV and FF = 0.60), respectively, under simulated AM 1.5 G solar irradiation (100 mW cm^?2). The data show that these novel polymeric metal complexes are suitable for DSSCs. Copyright © 2012 Society of Chemical Industry     

Main chain polymeric metal complexes based on linkage fluorenevinylene or phenylenevinylene with thienyl(8‐hydro xyquinoline)–cadmium (II) complexes as dye sensitizer for dye‐sensitized solar cells

Dye‐sensitized solar cells (DSSCs) have attracted interest from chemists in recent years because of their unique advantages: low cost, simple preparation technologies, and high efficiency. Three main chain polymeric metal complexes F, P1, and P2 connected with thienyl(8‐hydroxyquinoline)–Cadmium (II) complexes have been synthesized by Heck coupling and characterized by Gel Permeation Chromatography, Fourier transform infrared, 1H NMR, thermogravimetric analysis, TGA, UV‐vis, cyclic voltammetry, photoluminescence (PL) emission spectra, and the application of dye sensitizers in DSSCs has been studied. The DSSCs exhibited good performance with a power conversion efficiency of up to 1.77%, under simulated air mass 1.5 G solar irradiation. They possess good stabilities, indicating the polymeric metal complexes are suitable for the fabrication processes of optoelectronic devices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Platinum(II)‐Catalyzed Allylation of CO and CN Bonds under Hydrogenation Conditions

The nucleophilic addition of allylplatinum to a range of electrophiles including carbonyls, oximes, and hydrazones was examined. Platinum(II) catalysts and allene substrates were subject to hydrogenation conditions to generate nucleophilic allylplatinum complexes without using a stoichiometric amount of toxic and sensitive organometallic reagents. The allylplatinum intermediates reacted with CO and CN bonds to produce the corresponding homoallylic alcohol and amine derivatives in good yield. The Pt‐catalyzed allylation of CN bonds is the first example performed under hydrogenation conditions. A reaction mechanism initiated with the hydrometalation of allenes by Pt H species is proposed based on deuterium labeling studies.     

Effect of 1‐butyl‐3‐methylimidazolium iodide containing electrospun poly(vinylidene fluoride‐co‐hexafluoropropylene) membrane electrolyte on the photovoltaic performance of dye‐sensitized solar cells

Electrospun poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐HFP) membrane was prepared from a solution of 16 wt % of PVdF‐HFP containing acetone/N,N‐dimethyl acetamide (7:3 wt %). The prepared electrospun PVdF‐HFP membrane (esPM) was then soaked in ionic liquid electrolyte containing 0.5M LiI, 0.05M I₂ , and 0.5M 4‐tert butylpyridine, 0.5M 1‐butyl‐3‐methylimidazolium iodide (BMImI) in acetonitrile to get electrospun PVdF‐HFP membrane electrolyte (esPME). The effect of various concentrations of BMImI containing esPME on ionic conductivity was studied by AC‐impedance measurements and the diffusion co‐efficients was determined by linear sweep voltammetry. The photovoltaic performance of a DSSC fabricated using 0.5M BMImI containing electrospun PVdF‐HFP membrane electrolyte (0.5M BMImI‐esPME) has power conversion efficiency (PCE) of 6.42%. But the stability of the DSSC fabricated using 0.5M BMImI‐esPME was considerably superior to that fabricated using 0.5M BMImI containing liquid electrolyte (0.5M BMImI‐LE). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42032.     

Boosting the photovoltaic performance of Zn2SnO4‐based dye‐sensitized solar cells by Si doping into Zn2SnO4

In the present work, Zn₂SnO₄ nanoparticles were doped with silicon to improve their electrical and optical properties by the conventional solid‐state reaction method. The results showed that the minimum electrical resistivity of about 0.09 Ωcm was obtained for Zn₂SnO₄ nanoparticles with 3% Si doping. The decrease in the electrical resistivity can be attributed to the insertion of Si⁺⁴ atoms into the Zn⁺² and/or Sn⁺⁴ sites and also the formation of more oxygen vacancies in the Zn₂SnO₄ lattice. The formation of the more oxygen vacancy defect states in Si‐doped Zn₂SnO₄ nanoparticles was verified by photoluminescence spectroscopy. The efficiency of a dye‐sensitized solar cell based on 3% Si‐doped Zn₂SnO₄ was significantly better, by about 81%, compared to that of a cell based on the undoped Zn₂SnO₄. The enhancement in the efficiency can be ascribed to the facilitation of electron transport throughout a photoelectrode due to increase in the charge carrier concentration which was caused by Si doping.     

Tunable molecular weights of poly(triphenylamine‐2,2′‐bithiophene) and their effects on photovoltaic performance as sensitizers for dye‐sensitized solar cells

Despite the huge progress achieved over the past decade, the relationship between the molecular weights of dyes and the performance of dye‐sensitized solar cells (DSSCs) remains unclear. In this article, we report on the fine control of the number‐average molecular weight (M_n) of poly(triphenylamine‐2,2′‐bithiophene) (PPAT) dyes with cyanoacrylic acid moieties as acceptors. We found a correlation between the M_n and photovoltaic performance of these polymers when they were used for DSSC applications. In this study, three samples (PPAT‐01, PPAT‐02, and PPAT‐03) with different M_n values (M_ns = 1700, 2800, and 3500 g/mol) were prepared through the control of the polymerization time and characterized by analytical gel permeation chromatography and NMR. Under the same experimental conditions, the overall cell efficiency of the oligomer dyes showed a nonmonotonic tendency with increasing molecular weight. The power‐conversion efficiencies were 2.81% for PPAT‐01, 4.72% for PPAT‐02, and 1.88% for PPAT‐03. UV absorption measurements proved that PPAT‐03 formed aggregation, whereas PPAT‐01 and PPAT‐02 were in the monolayer state adsorbed on TiO₂. The larger aggregation decreased charge transfer; thus, poor photoelectric conversion performance was observed. Furthermore, a higher molecular weight reduced the amount of PPAT‐03 adsorbed on TiO₂, and this had a crucial effect on the performance of the cells because of the reduced photocurrent. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44182.     

Novel poly(phenylene ethynylene)‐type conjugated polymers containing diketopyrrolopyrrole or triphenylpyrazoline units in the main chain: synthesis,characterization and photophysical properties

BACKGROUND: Polymer‐based light emitting diodes (PLEDs) have received considerable attention as they combine the good mechanical and processing properties of polymers with semiconducting behavior, and can be easily fabricated as flexible devices. To obtain high‐performance PLED materials by balancing the carrier injection of poly(phenylene ethynylene)s (PPEs), polymers containing two aryl‐heterocyclic rings, namely diketopyrrolopyrrole (DPP) or triphenylpyrazoline (TPP), have been synthesized and investigated. RESULTS: PPE‐type polymers containing DPP or TPP units were synthesized using Heck–Sonogashira coupling methodology and characterized by ¹H NMR, Fourier transform infrared and UV‐visible spectroscopies, elemental analysis, gel permeation chromatography, photoluminescence (PL), X‐ray diffraction, thermogravimetic analysis and cyclic voltammetry. The polymers obtained are easily soluble in common solvents and form smooth and uniform films. They are yellow or red emitters as revealed by PL. In addition, they show large Stokes shifts, which is in agreement with their twisted molecular structures determined via quantum chemical calculations. CONCLUSION: PPE‐type polymers containing DPP or TPP units were successfully synthesized by coupling polymerization. They exhibit band gaps of 1.73 and 2.37 eV, respectively, and show potential as PLED materials. In addition, DPP‐containing polymers with a very low band gap could be applied as potential photovoltaic materials. Copyright © 2009 Society of Chemical Industry