Nano Composite PVA-TiO₂ Thin Films for OTFTs

Abstract

Pure PVA and composite thin films of poly vinyl alcohol (PVA)/Titanium dioxide (TiO2) were prepared on pre-cleaned glass substrates by Dip Coating Technique (DCT) and Metal Organic Deposition Technique (MODT). EDS and FTIR spectrum were used to identify the composition of the prepared films. The vibrational peaks observed at 1260 cm-1 and 851 cm-1 are assigned to C–C stretching and CH rocking of PVA. The characteristic band appearing at 1432 cm-1 is assigned to C–H bend of CH2 of PVA. The bands observed around 847 cm-1 and 601cm-1 belong to the asymmetric stretching of Ti–O–Ti groups. The last band at 460 cm-1 is due to the bending mode of Ti–O–Ti. The bands covered by Ti-O were located at 540, 700 and 950 cm-1. From the FTIR spectra, it is observed that some of the peaks of composite films were shifted and some of them were disappeared with respect to the pure compounds. This results manifested the conclusion about the specific interactions in composite polymer matrices and hence the complexation. Thus, complex formation in the composite polymer matrices has been confirmed from this analysis. The thickness of the coated films were measured by using an electronic thickness measuring instrument (Tesatronic-TTD-20), gravimetric method and cross checked by optical spectrophotometer. XRD spectra indicated the amorphous nature of the films. Surface morphology of the coated films was studied by scanning electron microscope (SEM). The surface revealed no pits and pin holes on the surface. Both as grown and annealed films showed predominantly amorphous nature. The observed surface morphology and thermal stability indicated that these films could be used as dielectric layer in organic thin film transistors.

Hybrid Pva-In2o3 Nano Thin Film for Transparent Optical Devices

“…The wide overlapping bands between 1054 and 1300 cm -1 may results from the superposing effect of In-O, In-O-C, C-O-C and it is a difficult to distinguish between them. The spectrum seems to be consistent with that previously reported work in literature [12][13][14]. The observed very weak peak at around 600 cm -1 may be attributed to In-OH mode [15].…”

“…The several peaks obtained between 400 cm -1 and 800 cm -1 is due to metal-oxide (possibility of In-O vibrations) bond [16]. The obtained M-O bond is in good agreement with previously reported work on metal oxide thin film in polymer matrix [12]. This results manifested the conclusion about the specific interaction in hybrid polymer matrices and hence the complexation.…”

“…A relatively broad absorption stretching band is observed at 3423-3432 cm -1 indicating the presence of polymeric association of the free hydroxyl groups and bonded OH stretching vibrations [11]. A broad O-H absorption stretching vibration is observed at 3423-3432cm -1 due to the result from the superposition of multiple polymeric H bonds associated with the crystalline phase and dimeric H bonds associated with the amorphous phase [12]. As the film is subjected to annealing at 50°C, 100°C and 150°C the intensity of the absorption band reduces with increase of annealing temperature.…”

“…3. PVA is well known as a crystalline polymer due to the strong intermolecular interaction between PVA chains through intermolecular hydrogen bonding [12]. The XRD patterns revealed a broad pattern (characteristics of small particle size) at 2θ=20-38 o was obtained for both as grown and for films subjected to annealing at 50˚C, 100˚C, 150˚C [20].…”

“…New technologies are demanding PVA materials with improved structure, morphology, electrical and optical modifications of traditional PVA for the development of nano devices. To further enhance the properties of this polymer, an inorganic material is added to PVA to form a hybrid, which could be lightweight, flexible and exhibit a good moldability [8][9][10]. To the best of our knowledge, there is no report on effect of annealing on structure, morphology and optical properties of hybrid PVA-In 2 O 3 thin films by dip coating method.…”