Nanocrystalline proprieties of TiO₂ thin film deposited by ultrasonic spray pulverization as an anti-reflection coating for solar cells applications

Abstract

Titanium oxide (TiO2) films have been synthesized on quartz, silicon and textured silicon substrates by chemical ultrasonic spray deposition. The textured silicon substrate was carried out using Na2CO3solution. The sample surface exhibits uniform pyramids with an average height of 5µm. In this paper, particular attention is given to the TiO2films prepared by spray ultrasonic system using Tetra iso-Propoxide Orthotitanate Titanium (TPOT) as a precursor. The solutions were sprayed onto substrates heated at various temperatures 350 - 550 °C. The properties of films as a function of temperature parameter were investigated using structural and optical analysis. According to XRD, FTIR and Micro-Raman spectroscopies, the anatase phase was found and exhibits nanograins of 9 to 15 nm in size. The indirect and direct bad gap were found to increase by increasing substrate temperature due to the decreasing of nanograins size and were estimated to be around 3.28 and 3.38 eV. A transmittance higher than 80% was found. This paper reports on anti-reflection coating application of TiO2layers due to its good transparency and appropriate refractive index varies between 2.19 - 2.40 at λ = 632.8 nm as a function of temperature determined by UVVisNIR spectrophotometer and Ellipsometry. To achieve optimum anti-reflection characteristics different anti-reflection designs were experimentally examined with polished and textured substrates. The average reflectance of the polished silicon used in this study is 39%, with TiO2it decreases to 9%. The textured surface reduces the average reflectance of silicon to be around 14% and it decreases dramatically to 5% after deposition of a single layer of TiO2as an anti-reflection coating. The gain in density of the short-circuit photocurrent assigned to the reduction of reflection losses up to 44% and 58% were predicted with TiO2single-coating in polished and textured silicon substrates respectively.

Morphological and optical properties of dielectric multilayer structures prepared with distinct precursor concentrations

“…However, the peak originated at 1742 cm −1 is associated with the carbonyl bond C=O which could be attributed to the non-hydrolytic sol-gel reaction of used acid and TTIP precursor. These vibration peaks coincide with the reported works [15,16].The trend of the FTIR curves is almost identical the samples which were prepared with low and high-precursor concentrations. To study the surface topography, we have performed the atomic force microscopy analysis of both the samples.…”

“…3(c and d). Similar, enhanced grains size with the increased precursor concentrations has been reported [16][17][18]. The high precursor concentration led to bigger crystallite size as a results increased grain size was observed.…”

“…SEM analysis revealed the deposition of homogeneous layers of SiO 2 and TiO 2 . By FTIR measurement, the vibration of Si-O-Ti bond was confirmed, however, the transmittance of the multilayer was found to be decreased from 4.58% to 0.55%, as shown by UV-Vis spectroscopy study [16]. H. H. Nguyen et al studied the effect of precursor concentration on TiO 2 thin film nanostructure using plasma chemical vapor deposition (PCVD) system.…”

Optimization of Antireflective Layers of Silicon Solar Cells: Comparative Studies of the Efficiency Between Single and Double Layer at the Reference Wavelength

“…There are several performance criteria for ARC. Among them are: control of the refractive index (n) of ARC, high transmittance for a wide solar spectrum, and the structure of the front surface of solar cells [2]. Various materials and thin films, including SiO 2 , SiN x , TiO 2 , Al 2 O 3 , etc., have been used for antireflective coating purposes depending on the type of solar cells [3].…”

Evaluation of the TiO2 Anti-Reflective Coating in PERT Solar Cells with Silicon Dioxide Passivation

“…The passivation with titanium dioxide depends on the technique used to deposit the layer and new methods have been developed. For instance, the chemical ultrasonic spray deposition was used to produce a single layer of TiO2 and the reflectance of textured silicon wafers was 5 % (Sali et al, 2017). The spin coating procedure was applied to deposit a TiO2/SiO2 thin film.…”