**2. Experiment**

The different experimental techniques have been used to study the properties of nanostruc‐ tured materials.

To reveal the change of the photorefractive properties, as the systems under study the or‐ ganic thin films based on conjugated monomer, polymer and liquid crystals sensitized with carbon nanotubes, fullerenes, shungites, graphenes oxides, or quantum dots have been chos‐ en. Polyimides (PI), 2-cyclooctylamino-5-nitropyridine (COANP), *N*-(4-nitrophenyl)-(*L*)-pro‐ linol (NPP), 2-(*N*-prolinol)-5-nitropyridine (PNP), nematic liquid crystals (NLCs) have been considered as organic matrixes. These conjugated systems are the good model with effective intramolecular charge transfer process which can be easy modify via sensitization by nano‐ objects. Carbon nanotubes, fullerenes, shungites, graphenes oxides, quantum dots content was varied in the range of 0.003-5.0 wt.%. The solid thin films have been developed using centrifuge deposition. The general view of these films is shown in Fig.1. The thickness of the films was 2-5 micrometers. The LC cell thickness was 5-10 micrometers.

**Figure 1.** Photographs of samples of pure (nk8) and nanoobjects-containing (nk10) PI films.

The nanostructured LC films have been placed onto glass substrates covered with transpar‐ ent conducting layers based on ITO contacts. The nanostructured monomer or polymer sol‐ id films have been deposited on the substrate with ITO contact. For the electric measurements of volt-ampere parameters, gold contact has been put to the solid thin films upper side. The picture which can interpret the placement of the conducting contacts on the solid conjugated organic thin films is shown in Fig.2.

**Figure 2.** Interpretation of the solid thin films with the conducting layers

regarded to their high conductivity, strong hardness of their C-C bonds as well as compli‐

These peculiarities of carbon nanoobjects and their possible optoelectronics, solar energy, gas storage, medicine, display and biology applications connecting with dramatic improve‐ ment of photorefractive, spectral, photoconductive and dynamic parameters will be under consideration in this paper. In comparison with other effective nanoobjects the mail accent will be given namely on carbon nanotubes (CNTs) and their unique features to modify the

The different experimental techniques have been used to study the properties of nanostruc‐

To reveal the change of the photorefractive properties, as the systems under study the or‐ ganic thin films based on conjugated monomer, polymer and liquid crystals sensitized with carbon nanotubes, fullerenes, shungites, graphenes oxides, or quantum dots have been chos‐ en. Polyimides (PI), 2-cyclooctylamino-5-nitropyridine (COANP), *N*-(4-nitrophenyl)-(*L*)-pro‐ linol (NPP), 2-(*N*-prolinol)-5-nitropyridine (PNP), nematic liquid crystals (NLCs) have been considered as organic matrixes. These conjugated systems are the good model with effective intramolecular charge transfer process which can be easy modify via sensitization by nano‐ objects. Carbon nanotubes, fullerenes, shungites, graphenes oxides, quantum dots content was varied in the range of 0.003-5.0 wt.%. The solid thin films have been developed using centrifuge deposition. The general view of these films is shown in Fig.1. The thickness of the

films was 2-5 micrometers. The LC cell thickness was 5-10 micrometers.

**Figure 1.** Photographs of samples of pure (nk8) and nanoobjects-containing (nk10) PI films.

The nanostructured LC films have been placed onto glass substrates covered with transpar‐ ent conducting layers based on ITO contacts. The nanostructured monomer or polymer sol‐

cated and unique mechanisms of charge carrier moving.

398 Syntheses and Applications of Carbon Nanotubes and Their Composites

properties of the optical materials.

**2. Experiment**

tured materials.

The bias voltage applied to the photosensitive polymer layers has been varied from 0 to 50 V. The current–voltage characteristics have been measured under the illumination condi‐ tions from dark to light. Voltmeter-electrometer В7—30 and Characteriscope—Z*,* type TR-4805 has been used for these photoconductive experiments.

The photorefractive characteristics have been studied using four-wave mixing technique analogous to paper [7]. The experimental scheme is shown in Fig.3.

**Figure 3.** An experimental scheme: 1 – Nd-laser; 2 – second harmonic convertor; 3 – telescope; 4 – diaphragm; 5 – rotating mirror; 6 – beam-splitting mirror; 7 – prism; 8 – sample; 9 – lens; 10 - photodetector.

The second harmonic of pulsed Nd-laser at wave length of 532 nm has been used. The laser energy density has been chosen in the range of 0.005-0.9 J×cm-2. The nanosecond laser re‐ gime with the pulse width of 10-20 ns has been applied. The amplitude-phase thin gratings have been recorded under Raman-Nath diffraction conditions according to which Λ-1 ≥ *d*, where Λ–1 is the inverse spatial frequency of recording (i.e., the period of the recorded gra‐ ting) and *d* is the film thickness. In the experiments the spatial frequency was in the range of 90-150 mm-1.

ized due to their high electron affinity energy (for example, electron affinity energy is close to 2 eV for shungites [9], to 2.65 eV for fullerenes [5,8] and to 3.8-4.2 eV for quantum dots [10]) that is more than the ones for intramolecular acceptor fragments (for example, electron affinity energy of COANP acceptor fragment is close to 0.54 eV [11] and to 1.14-1.4 eV for polyimide one [12]). Regarding graphenes it is necessary to take into account the high sur‐ face energy and planarity of the graphenes plane which can provoke to organize the charge transfer complex (CTC) with good advantage too. Regarding the CNTs it should be drawn the attention on the variety of charge transfer pathways, including those along and across a CNT, between CNTs, inside a multiwall CNT, between organic matrix molecules and CNTs,

Carbon Nanotubes Influence on Spectral, Photoconductive, Photorefractive and Dynamic Properties of the Optical

Materials

401

http://dx.doi.org/10.5772/50843

**Figure 5.** The rate of release of C70 molecules on heating of systems: (*1*) COANP with 5 wt % of C70 and (*2*) polyimide

It should be noticed that some supporting CTC results for PIs and COANP systems sensi‐ tized with nanoobjects can be presented via mass-spectrometry experiments. It is easy to show the organization of CTC using fullerenes acceptor. Really, the mass spectroscopy data point to the effective CTC formation between fullerene and donor part of PI (triphenyla‐

with 0.5 wt % of C70

and between the donor and acceptor fragments of an organic matrix molecule.

The spectral characteristics have been tested using Perkin Elmer lambda 9 spectrophotome‐ ter. Dynamic features of nanoobjects-doped LC films have been studied via the four-wave mixing technique and the Frederick's scheme one. Atomic force microscopy (AFM) method using equipment of "NT-MDT" firm, "Bio47-Smena" in the "share-force" regime has been applied to analyze the diffraction relief into the solid conjugated nanostructured thin film.
