Photovoltaic properties of nanocomposites of cadmium alkanoates with semiconductor nanoparticles

Ionic liquid crystals of metal alkanoates in the smectic phase (+150оС) can be act as nanoreactors for the chemical synthesis of nanoparticles (NPs) of different types: semiconductors, metal and core/shell. The technology of chemical synthesis of nanoparticles directly in the matrix of an ionic liquid crystal contributes to the fact that the matrix acts as a stabilizer of nanoparticles, which leads to a small dispersion of the sizes of NPs, and the content of NPs in the matrix can reach large concentrations (up to 8 mole%) [1]. The smectic liquid crystal phase of the nanocomposite retains its layered structure under conditions of slow cooling. By such a way, anisotropic glass nanocomposites with layered smectic-like structures are formed at the room temperature with incorporated nanoparticles inside the matrix. The nanocomposits exhibits anisotropy of electric conductivity, which is directed mainly along cation-anion layers in the smectic-like matrix. The conduction mechanism is of ionic type with the activation energy ~0.8 eV for the nanocomposites with semiconductor NPs.For the first type, we detect the photovoltaic effect both in a pure matrix and in the nanocomposites with semiconductor NPs, in "sandwich"-like cells under illumination of samples perpendicular to the cation-anion layers by a lamp that emits in a wide range of wavelengths in the ultraviolet - blue diapason of the spectrum. Different dependences of short-circuit current are obtained from the temperature in LC mesophase and in anisotropic glasses. The magnitude of the short-circuit current increases in 3 orders of magnitude in the nanocomposites compared with the short-circuit current of the pure matrix, and the relaxation time is significantly reduced. It is established that photo-stimulated charge distribution occurs due to photo-generation of ions and transmission of electric field along the cation-anion layers of the matrix [2].[1] Zhulai D.S, Bugaychuk S.A., Klimusheva G.V., Mirnaya T.A., Asaula V.N., Handziuk V.I ., Vitusevich S.A. Structural characteristics of different types of nanoparticles synthesized in mesomorphic metal alkanoates // Liquid Crystals, DOI: 10.1080/02678292.2016.1276979 (2017)[2] Zhulai D, Kovalchuk A, Bugaychuk S, Klimusheva G, Mirnaya T., Vitusevich S. Photoconductivity of ionic thermotropic liquid crystal with semiconductor nanoparticles // Journal of Molecular Liquids, DOI: 10.1016/j.molliq.2017.12.097 (2017

Вплив напівпровідникових та металевих наночастинок на діелектричні властивості іонної матриці октаноата кадмію

Dielectric properties of ionic composites consisted of cadmium octanoate matrix and semiconductor or metal nanoparticles have been investigated. The nanoparticles of different nature (semiconductor CdS, metal Au, and metal core-semiconductor shell Au-CdS) were chemically synthesized in the smectic A phase of (Cd+2(C7H15COO)−2, CdC8) that was used as a nanoreactor. These nanocomposites are very stable and well ordered; the size and shape of the nanoparticles (NPs) are well controlled during the synthesis. The main aim of the research was to examine the influence of nanoparticles on the dielectric properties of ionic matrix, which has smectic A ordered structure. Electrical characteristics were investigated at different temperatures, which correspond to different phases of the material. The conductivity of nanocomposites has an activation nature. The electrical conductivity anisotropy confirms the structural anisotropy of the nanocomposites. The conductivity of the nanocomposite along the cation-anion layers is higher by 2 orders of magnitude than that across the cation-anion layers. Basing on the experimental data, we proposed the simple model of the charge carriage process

Electro-optical properties of a liquid crystalline colloidal solution of rod shaped V2O5 nanoparticles and carbon nanotubes in an alternating current electric field

We study the liquid crystalline phase behaviour of the two-component aqueous colloidal suspensions of multiwalled carbon nanotubes (MWCNTs) and rod-like vanadium pentoxide (V2O5) nanoparticles. The phase diagram features a stable nematic phase in a wide range of concentration of solid components. The oriented nematic phase of the two-component suspension was exposed to the action of alternating current electric field. A variation in MWCNTs concentration within 0.01–0.51 wt.% demonstrates a significant increase in the optical response of the system to the applied electric field