Synthesis and Characterisation of Indium Tin Oxide Thin Films for Dye-Sensitised Solar Cells using Natural Fruit Extracts

The study focuses on the application of natural fruit extract of blackberry in dye-sensitised solar cells (DSSC) as a photosensitiser. The widespread availability of the fruits and juices, high concentration of anthocyanins in them ease of extraction of anthocyanin dyes from these commonly available fruits, enable them as a novel and inexpensive candidates for solar cell fabrication. Anthocyanins are naturally occurring biodegradable and non-toxic compounds that can be extracted with minimal environmental impact and provide environmentally benign alternatives for manufacturing dyes in DSSC synthesis. Indium tin oxide (ITO) thin films are synthesised using sol-gel and spin-coating techniques. ITO characteristics are determined by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transforms infrared spectra (FTIR) measurements. To find the transmittance percentage in the visible region of thin films, atomic force microscope (AFM) and UV-Vis spectroscopy analyses were done. The nanocrystalline phase of the synthesised ITO films was confirmed through XRD. SEM was used to analyse the morphology of the synthesised ITO films. Cubic, columnar (edge length ~ 35-45 nm) and rod-shaped (~110 x 14) particles were observed. Narrow size distribution was observed for spherical particles in the range of ~13-15 nm. The FTIR analysis revealed the presence of carboxyl and hydroxide functional groups. The AFM analysis revealed the uniform spread of the synthesised dye, while the visible region absorbance and transmittance of the synthesised ITO films were confirmed through UV-vis spectroscopy. The thin films showed 83-86% of average transmittance. Finally, we fabricated a dye-sensitised solar cell with desired properties. The characterisation results confirmed that the synthesised material could be used in the DSSC application.

Improved Electrical and Optical Properties of Ultra-Thin Tin Doped Indium Oxide (ITO) Thin Films by a 3-Dimensionally Confined Magnetron Sputtering Source

The ultra-thin tin doped crystalline indium oxide (ITO) films (≤50 nm) were successfully deposited by a 3-dimensionally confined magnetron sputtering source (L-3DMS) at the temperature lower than 100 °C. The resistivity and the mobility of the ultra-thin ITO films deposited at a low processing temperature were about ~5 × 10−4 Ω · cm and >30 cm2/Vs, respectively, for the thickness of 30 nm. The high quality of the ultra-thin ITO films deposited by L-3DMS is believed to be related to the improved crystallinity with oxygen vacancies of the ITO films by high density plasma and low discharge voltage of the L-3DMS which enables the formation of a crystalline structure a low processing temperature.

Preparation of High-Performance Metal-Free UV/Near Infrared-Shielding Films for Human Skin Protection

A series of metal-free UV/near infrared (NIR)-shielding coatings are successfully fabricated by shielded cathodic arc plasma evaporation (CAPE) and substrate-biased RF magnetron sputtering processes. The UV/NIR-shielding coatings comprising quarter-wave stacks of TiO2/SiO2 multilayers and high-conductivity sputter-deposited ITO films with a thickness in the range of 200–600 nm could block IRA and IRB radiations, respectively. The total thicknesses of UV/near infrared-shielding films are in the range from 375 nm to 1513.8 nm. The anatase-phase TiO2 films with absorption edge located at ∼375 nm were deposited by shielded CAPE at ∼100 °C. Further, the well-crystallized ITO films were found to have high free-electron concentrations (1.12 × 1021 cm−3), resulting in strong absorption of IRB due to the plasmon resonance absorption. The optimal optical design and ITO film thickness were investigated, and the TiO2(SiO2/TiO2)3 multilayer combined with an ITO film thickness of 400 nm was found to provide a high NIR-shielding rate of 94.8%, UVB to UVA-shielding rate of 92.7%, and average visible light transmittance of 68.1%. Further, human skin cells protected by a UV/NIR-shielding coating showed significantly decreased reactive oxygen species generation and inflammatory cytokine expression as compared to those of unprotected cells. The results demonstrate that the development of multifunction coatings have potential for transparent heat insulation windows and human skin protection against UV/IR radiations.

Electrochromic Properties of PANI/TiO2 Nanocomposite Films Prepared by Electropolymerization

PANI/nc-TiO2/ITO composite films were prepared by electrochemical method where the monomer aniline was polymerized onto nano-porous TiO2/ITO films (PANI/nc-TiO2/ITO). The PANI/nc-TiO2 heterojunctions were formed in the composite films due to the insertion of PANI in nano-porous TiO2 particles. PANI/ITO films exhibited a reversible electrochromic display (ECD) performance when cycled in 0.1M LiClO4 + propylene carbonate. The response times of the electrochromic coloration and bleaching of the PANI/nc-TiO2/ITO electrode were 15 s and 20 s, respectively. Electrochromic efficiency of the films reached a value as large as 12.25 cm2´C-1. Taking advantage of the large EC efficiency and electrochemical stability as well as the simplicity of the fabrication process, PANI/nc-TiO2 composite films can be used for preparation of electrochromic smart windows, in term of the large-area production in particular.

IMPROVEMENT IN STRUCTURAL, OPTICAL AND ELECTRICAL PROPERTIES OF ITO FILM THROUGH AlN AND HfO2 BUFFER LAYERS

Indium Tin Oxide (ITO) films were deposited on glass substrate using radiofrequency (RF) magnetron sputtering technique. To improve the physical characteristics of the ITO film, AlN and HfO2 buffer layers were deposited on glass prior to the film deposition. The ITO/glass, ITO/AlN/glass and ITO/HfO2/glass films were annealed using CO2 laser and electrical oven heating methods. The crystallinity of the ITO film was improved due to the incorporation of AlN and HfO2 buffer layers and also by the post-deposition annealing process. The optical transmittance of the ITO was also increased due to the presence of the buffer layers. Similarly, the annealed ITO films grown on buffer layers exhibited lower values of the sheet resistance as compared to the film deposited without buffer layers. The laser annealing technique was more found to be more effective in reducing the ITO sheet resistance.