Photovoltaic Properties of Polymer/Fe₂O₃/Polymer Heterostructured Microspheres

Abstract

The Fe2O3 particles with diameters of 3−5 nm were encapsulated between the core and the shell of polymer via emulsion polymerization into the heterostructured microspheres, which were observed through TEM images. The photovoltaic response of the composites, which was studied by the electric-field-induced surface-photovoltage-spectroscopy technique, appeared only if there was an external electric field (EEF) and its decay was much slower than that of Fe2O3 nanoparticles themselves. A reasonable energy band model was supposed to explain this phenomena and indicated that the polymer shell acted as an electric-passivation layer of the semiconductor Fe2O3 particles. The charge-separation process in the struture was also analyzed with this model.

Effects of surface-modification with Bi2O3 on the thermal stability and photoinduced charge property of nanocrystalline anatase TiO2 and its enhanced photocatalytic activity

“…The ultraviolet-visible diffuse reflectance spectra (UV-vis DRS) of the samples are recorded with a Model Shimadzu UV2550 spectrophotometer. The SPS measurements of the samples are carried out with a home-built apparatus that had been described in detail elsewhere [25][26][27][28]. The powder samples are sandwiched between two ITO glass electrodes, and the change of surface potential barrier between in the presence of light and in the dark is SPS signal.…”

“…7, altogether with the SPS response of crystal Bi 2 O 3 (inset) prepared by directly calcining the Bi(NO 3 ) 3 at 600 8C. During the process of SPV measurement, the ITO glass can strongly absorb the light with the wavelength lower than 330 nm, which results in a corresponding weak or even no SPV signal [27]. It can be seen that the T500 and BT600 TiO 2 samples display obvious SPS response peaks at about 345 nm, which are attributed to the electronic transitions from the valence band to conduction band (O 2p !…”

“…Compared with the T500 TiO 2 sample, the strong SPS response of the BT600 TiO 2 sample is explained mainly by the following two factors. One is that the increase in the crystallinity makes semiconductor electronic band structure perfect so as to enhance the built-in electric field strength [27,32], meanwhile leading to the decrease in the surface defect amount, consequently promoting charge separation and transfer. The other is that the Bi 2 O 3 -TiO 2 composite nanoparticles are formed.…”

Preparation and characterization of nanoparticle Ru:TiO2 films and their photocatalytic activity

“…The SPS measurements of the samples were carried out with a home-built apparatus that had been described elsewhere [9][10]. The generation of photovoltage arises from the creation of electron-hole pairs, followed by the separation under a built-in electric field (the space-charge layer).…”

Nanocompósitos de matriz polimérica: estratégias de síntese de materiais híbridos

“…Esta revisão bibliográfica refere-se a nanocompósitos de matriz polimérica de interface inorgânica/orgânica. A incorporação de cargas inorgânicas em polímeros origina materiais com maior resistência mecânica 11 , maior estabilidade térmica 12 ou com propriedades ópticas 13 , magnéticas 14 ou eléctricas 15 superiores. As cargas tendo dimensões nanométricas (1-500 nm) apresentam uma área de superfície elevada, promovendo melhor dispersão na matriz polimérica e por isso uma melhoria das propriedades físicas do compósito que dependem da homogeneidade do material.…”