Table of Content

15 May 2013, Volume 31 Issue 3

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The Exciton Multification and the Third Generation of Solar Cell

WU Shi-kang

2013, 31(3):  161-174.  DOI: 10.7517/j.issn.1674-0475.2013.03.001

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Recently, the pathway and the mechanism of exciton multification for improving the photo-electric conversion efficiency of solar cell become an important aspect with extensive attention. In this review, many factors such as the impact ionization, phonon bottleneck, cooling of hot-electron, electron transfer process and the Auger recombination, which may affect the formation of the second electron-hole pair in system have been discussed. Review is also briefly to introduce the method of (Pump-Probe) transient absorption spectrum (TA) measurement for studying the dynamic process of exciton multification. And several examples are listed for the illustration of this phenomenon in semi-conductor QD systems which have been applied as a new materials in the third generation of solar cell.

Recent Progress in Preparation and Application of ZnO Mesocrystal

ZHAO Bin, MENG Wan, SONG Kai

2013, 31(3):  175-185.  DOI: 10.7517/j.issn.1674-0475.2013.03.002

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ZnO mesocrystal is considered as a new class of photoelectric functional materials that exhibits excellent electrical, optoelectronics, photochemical and catalytic properties. Thus, it shows a broad prospect of application in sensors, photocatalysis, high frequency generator, etc. In this review, the research progress in the preparation of ZnO mesocrystal is presented, including solvothermal method, precipitation method, ionic liquid method, sol-gel method, etc. Their advantages and disadvantages are summarized. Furthermore, the progress in the application is also introduced. Finally, the prosperity of the research of mesocrystal ZnO is proposed.

Effect of Anion on Crystal Form of TiO₂ and Their Photocatalytic Performance

HAN Yan-he, JIANG Jin-hai, JIANG Li, LI Bao-qin, LIU Lu, CHEN Jia-qing, LIANG Cun-zhen

2013, 31(3):  186-196.  DOI: 10.7517/j.issn.1674-0475.2013.03.003

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SO₄^-2, F^-, Cl^- and PO₄^-3 were selected as anion to investigate the morphology and the crystal form of TiO₂ (named as TiO₂-S、TiO₂-F、TiO₂-Cl and TiO₂-P) prepared with hydrothermal synthesis in this study. Their photoctalytic performance were also investigated. Form SEM photo, TiO₂-S、TiO₂-F、TiO₂-Cl and TiO₂-P present shape of particle, decanedron, acanthosphere, and irregular bulk, respectively. XRD patterns showed that TiO₂-S and TiO₂-F were both anatase structure, TiO₂-Cl was rutile structure, and TiO₂-P was a mixed phase of anatase, rutile and brookite. These were indicated by the UV-Vis diffuse reflectance spectroscopy. XPS spectrum showed that four TiO₂ nanometer materials are affected by the anion doping. The photocatalytic activities of the samples were evaluated by rhodamine B degradation. The results revealed that the order of photocatalytic efficiency was TiO₂-F>TiO₂-S>TiO₂-Cl>TiO₂-P, which indicated that the photocatalytic activity of anatase with {001} facets and F was higher than rutile's and brookite's.

Encapsulate Porphyrin or Fullerene Derivatives in PMADQUAT/PSt-PAA Polyion Complex Aggregates for Enhanced Singlet Oxygen Yields

LI Hai-xia, GAO Yun-yan, OU Zhi-ze, JIN He-lin, CAO Lu, CHEN Chen

2013, 31(3):  197-207.  DOI: 10.7517/j.issn.1674-0475.2013.03.004

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The polystyrene-poly(tert-butyl acrylate) (PSt-PtBuA) block copolymer was synthesized using atom transfer radical polymerization (ATRP) method, and the polystyrene-poly(acrylic acid) (PSt-PAA) was obtained by the hydrolysis of PSt-PtBuA under acidic condition. The copolymers are characterized with proton nuclear magnetic resonance (¹HNMR) and gel permeation chromatography (GPC). The polymer PSt-PAA can form aggregates in the buffer solution of Tris-HCl (pH=7.0), with the critical aggregation concentration (CAC) of 0.015 g/L. The polyion complex (PIC) aggregates can be formed between poly-2-[(methacryloyloxy)-ethyl]trimethylammonium chloride (PMADQUAT) and PSt-PAA through electrostatic interaction. When the weight ratio of PMADQUAT:PSt-PAA is 3:1, the CAC of aggregates becomes 0.005 g/L. Dynamic light scattering (DLS) and transmission electron microscope (TEM) results indicate that the particle diameters become smaller after forming PIC aggregates. The photosensitizers, such as diethyleneglycolmonomethylether modified fullerene (MDG-C₇₀), protoporphyrin (PPIX), zinc-meso-tetraphenylporphine (ZnTPP) and 5,10,15,20-tetraphenylporphin (TPP) can be encapsulated into the polymer aggregates, thereby enhancing their solubility in the buffer solution. Under irradiation, the yields of singlet oxygen of MDG-C₇₀, PPXI, ZnTPP and TPP in PIC aggregates are 1.64, 2.63, 2.60 and 2.20 times, respectively, compared with that in PSt-PAA aggregates. The singlet oxygen is not detected in the buffer solutions of these photosensitizers, due to the aggregation of photosensitizer. These results suggest that encapsulation of photosensitizer in PIC aggregates is one of the effective ways to enhance singlet oxygen yield of photosensitizer.

The Preparation and Polarizing Property Studying in Modified Direct Gray D-Cu²⁺ Metal Complexes

FU Hua, HAN Ai-xia

2013, 31(3):  208-214.  DOI: 10.7517/j.jssn.1674-0475.2013.03.005

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The new compounds HDP were obtained by chemical reaction and then eomplexed with Cu²⁺. The intermediate HDP-Z was synthesized by diazotization and coupling reaction with direct gray D as raw material. And colorful polarizing films were obtained by extension, racking and desiccation of PVA film after dyed by HDP and HDP-Z. The polarizing property in near ultraviolet region and visible spectra were measured with UV spectrophotometer.The results showed that the polarizing property of the colorful polarizing films with HDP and HDP-Z was improved about 50 nm in degree of polarizing >60% ranged 450—700 nm; the polarizing property of the colorful polarizing films with Cu²⁺ increased about 5%, and had polarizing in near ultraviolet region.

The Study of Aggregation Properties of p-(n-Alkyl)-benzyl Polyoxyethylene Ether Carboxybetaine by Steady-State Fluorescence

DONG Lin-fang, XU Zhi-cheng, CAO Xu-long, WANG Qi-wei, ZHANG Lei, ZHANG Lu, ZHAO Sui

2013, 31(3):  215-221.  DOI: 10.7517/j.issn.1674-0475.2013.03.006

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The values of cmc, micelle micropolarity and γ_cmc of p-(n-alkyl)-benzyl polyoxyethy-lene ether carboxybetaine (ABECB) have been measured by fluorescence and Wilhelmy-plate method. It indicated that probe (pyrene) fluorescence emission spectra method could be used to determine the critical micelle concentration (cmc) of p-(n-alkyl)-benzyl polyoxyethylene ether carboxybetaine, and the results are compatible with that of Wilhelmy-plate method. The values of cmc and γ_cmc show that these surfactants have high surface activity. The micellar micropola-rity was observed to decrease, as the change of carbon atom number of the substituted hydrophobic chain of benzene ring, while the effect of increasing polyoxyethylene number on micellar micropolarity is little.

Synthesis and Spectroscopic Properties of 1,4-di(thiophen-2-yl)phthalazines

XU Wei, XUE Min-zhao, SU Yue-zeng, ZHANG Fan

2013, 31(3):  222-228.  DOI: 10.7517/j.issn.1674-0475.2013.03.007

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Organic conjugated molecules comprising 2,3-benzopyridiazine as electron-withdrawing core and thiophene derivatives as electron-donating arms, have been successfully synthesized in good yields. The spectroscopic properties of these molecules exhibited that introduction of the alkyl chains at different positions of the thiophene moieties, can effectively tune the band gap of the conjugated molecule. These preliminary results could be definitely helpful for establishing the structure-property correlation of the family of the conjugated molecules.

Preparation and Characteristics of Magnetic TiO₂ Photocatalysts

FEI Xue-ning, LIU Xing-xing, LI Jin-rui, JIANG Yuan-guang

2013, 31(3):  229-237.  DOI: 10.7517/j.issn.1674-0475.2013.03.008

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A magnetic TiO₂ photocatalyst of Fe₃O₄ magnetic core was prepared with a sol-gel method, and its photocatalytic activity was evaluated by the photo degradation of methyl orange aquous solution. The effects of Fe doping amount, calcination temperature and calcination time on the photocatalytic activity were investigated. The results showed that the optimal preparation conditions were of 5% Fe doping amount, 450 ℃ calcination temperature and 2 h calcination time. The prepared catalyst was characterized by thermo-gravimetric differential thermal analysis (TG-DTA), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis) and transmission electron microscope (TEM), and the results showed that prepared catalyst had a core-shell structure with the coating of TiO₂ on the surface of magnetic core. The original magnetic Fe₃O₄ core was oxidized by high temperature calcination .There was a red shift in the absorption band edge of prepared catalyst, its absorption intensity in the visible light region increased slightly, and the average particle size of prepared catalyst was 20 nm.