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New type of porphyrin - perylene imide molecule array synthesis and photoelectric properties of

Author: WangFuLing
Tutor: TangJianGuo
School: Qingdao University
Course: Materials Science
Keywords: The porphyrin - perylenediim molecular array Fluorescence Quenching Electron transfer and energy transfer Aggregation structure Photoelectric conversion efficiency
CLC: O626
Type: PhD thesis
Year: 2011
Downloads: 73
Quote: 0
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Abstract

The porphyrin compound chlorophyll molecules in the ideal artificial photosynthesis research alternative compounds with unique structural and functional characteristics. Flower imide compounds having excellent thermal and chemical stability, the chemical can be modified, and having excellent photoelectric properties. Both connected through a certain way and build into the porphyrin - spend imide molecular array, expected to be more excellent optical and electrical properties. In this thesis, on the basis of molecular array of the porphyrin at home and abroad - to spend imide summary of the research progress in the last ten years, the show the porphyrin - molecular array perylenediim molecular optoelectronic devices photoelectric conversion aspects excellent performance, pointed out that the study area There are three main issues: (1) synthetic route is long, low yield, the variety and quantity of the molecular array less; (2) the study of the molecular array aggregation structure almost blank; (3) at home and abroad on the porphyrin - spend imide molecules array of photophysical and photochemical properties of more of these molecular arrays in the photoelectric conversion device, such as organic solar cell research rarely. Based on the ideas of this thesis focuses on porphyrins - spend imide the design and synthesis of molecular arrays, study and exploration of the electronic structure, aggregation structure, and focus on the molecular array of charge-transfer and energy transfer process , preliminary studies in photoelectrochemical cells and organic thin film solar cell, the photoelectric conversion performance. Firstly, the use of the Sonogashira coupling reaction the synthetically prepared two porphyrins - spend polyimide molecular array the PDI-ZnPOR2 and PDI-ZnPOR4. Means of Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and elemental analysis characterized the detailed characterization of the intermediate and the chemical structure of the target molecule array, and preliminary exploration to optimize the conditions of the synthesis of the compounds. Electrospray ionization mass spectrometry and X-ray photoelectron spectroscopy results further confirm the structure of the two molecular arrays. UV - visible absorption spectroscopy, electrochemistry and other methods of synthesis of molecular arrays the PDI-ZnPOR2 and the PDI-ZnPOR4 electronic structure. The study found that the molecular array the PDI-ZnPOR2 mainly shows the absorption peak of the porphyrin chromophore, and two new characteristic absorption peak appears in the long wavelength region, indicating that the molecular array in the porphyrin and flowers imide group $ strong electronic interactions in the ground state; rather weak electronic interaction between the porphyrin array the PDI-ZnPOR4 in the ground state molecules and spend imide primitives mainly porphyrin Health simple superposition of the absorption peak of the chromophore and perylene imide chromophore. Cyclic voltammetry curves prove molecular array PDI-ZnPOR2 and PDI-ZnPOR4 exhibit reversible oxidation and reduction process; addition, after calculated the molecular array of PDI-ZnPOR2 the energy gap of 1.57 eV and the energy gap of the PDI-ZnPOR4 1.59 eV, the narrow band gap characteristics to the two molecular array is expected to be applied to the field of organic semiconductor and solar cell. Focus on of the the molecular array PDI-ZnPOR2 (?) Mouth PDI-ZnPOR4 in dilute solution, charge transfer and energy transfer processes, and excited-state decay mechanism. Using 430 nm monochromatic excitation of the porphyrin chromophore in the molecular array, the molecular array shown porphyrin chromophore weak fluorescence emission, relative to the reference than the monomer compound, the molecular array of the fluorescence intensity was significantly reduced, indicating that the molecular array from the porphyrin to spend imide primitive light-induced electron transfer process. When the molecular array shows that the fluorescence of the porphyrin chromophore using 560 nm light the excited molecular array of flowers imide chromophore occurs when the perylene imide primitives strong fluorescence quenching, and fluorescence intensity significantly reduced, which reveals the molecular array takes place from the light of the the perylene imide primitives to porphyrin induced energy transfer process, the porphyrin chromophore in an excited state, ensued from porphyrin primitives to spend imide primitives charge transfer process. These results indicate that regardless of the excitation of molecular arrays porphyrin chromophore or spend imide chromophore efficient intramolecular charge transfer occurs from porphyrin to spend imide primitive between. Relative to the non-polar solvent toluene molecule arrays in tetrahydrofuran showed strong fluorescence quenching phenomenon, further confirmed the molecular array photoexcitation existence by the porphyrin chromophore to spend imide chromophore efficient charge transfer. The test results show that the time-resolved fluorescence spectroscopy of molecular arrays photoinduced intramolecular electron transfer does occur. SEM and TEM test means a preliminary study on the aggregation structure of molecular arrays in different solvents. Different polarity of the solvent, the aggregation structure of the molecular array is also different, solvent-induced changes in molecular aggregation state. The XRD results show that the molecular array is the presence of an amorphous state. Thermal gravimetric analysis (TG) and differential scanning calorimetry (DSC) and results are shown an array of two molecules having a good thermal stability and physical stability, sufficient to meet the requirements of production of the solar cell device. The molecular array the PDI-ZnPOR2 and the PDI-ZnPOR4 having a good light collection performance, and light-induced electron spin resonance results show that the photoinduced intramolecular electron transfer process occurs both in the thin film state, so that an array of two molecules in the photoinduced shows the potential value of the charge separation devices. Photoelectrochemical cells and organic thin film solar cells we use molecular array the PDI-ZnPOR2 and the the PDI-ZnPOR4 prepared to conduct a preliminary study and discussion, and its photoelectric conversion performance. The study found The molecular array the PDI-ZnPOR2 and of PDI-ZnPOR4 the membrane electrode showed obvious photovoltaic effect can produce a fast and stable photocurrent under simulated sunlight. On this basis, the use of the spin coating was prepared the to molecular array the PDI-ZnPOR2 and the PDI-ZnPOR4 monolayer film as the active layer solar cell. Under irradiation of AM 1.5 simulated sunlight the molecular array the PDI-ZnPOR2 and PDI-ZnPOR4 monolayer film device of the active layer, the photoelectric conversion efficiency is very low, and this is mainly because the imide group of the core of the flower in the molecular array element surrounded by porphyrin surrounded cause electron transport channels are blocked, resulting in the Quenching the probability of electron and hole recombination greatly increased. Porphyrin - Flower imide molecular array solar cell devices work remains to be improved, due to the experimental conditions and time limits, failed to further the relationship between the state of aggregation of the molecular array structure and performance of the device; devices photoelectric conversion efficiency is very low, the device performance optimization work remains to be further carried out. Preliminary research work of the papers in this regard as the porphyrins - provides the basis for the perylene imide molecule array material in organic solar cells.

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