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Optical properties and bandgap analysis of multilayer sol-gel Ba1-xGdxTiO3 thin films for AR coating application



  1. Physics department, College of Science, University of Jeddah, Jeddah, Saudi Arabia
  2. Unit Process Development Engineer, Infineon Technologies (Kulim) Sdn Bhd. Kedah, Malaysia


Perovskites are promising materials for being used as an antireflection (AR) coating in conventional solar cells due to their high refractive index and reasonable energy bandgap. In this work, perovskite-structured Ba1-xGdxTiO3 thin films at different Gd3+ contents and thicknesses have been prepared via the sol-gel technique and tested using UV-Vis spectroscopy to investigate their possibility of being used as an AR coating. The results show relatively high transmittance and low reflectance for all films in the range of wavelengths from 400 nm to 850 nm; the variation of transmittance and reflectance with Gd3+ content and film thickness is attributed to the scattering of light with the microstructure. In the range of wavelengths from 200 nm to 400 nm, high absorbance is observed that is gradually reduced with the Gd3+ ratio and increases with film thickness, which is attributed to the grain size effect. The optical bandgap energy for films shows an increase from 3.94 eV to 4.14 eV as the Gd3+ content increases from 0.05 to 0.3, while it decreases from 3.84 eV to 3.77 eV with the film thickness, which is also correlated to the grain size variation. The relatively high energy bandgap, high transmittance, low reflectance, and low absorption for Ba1-xGdxTiO3 thin films in the wavelength range of 400-850 nm make them potential candidates for AR coating in conventional solar cells. The high absorption in the wavelength range of 200 nm to 400 nm leads to conclude using a top layer of these films is suitable for UV absorption in addition to their role as an antireflection layer for visible wavelengths..


Ba1-xGdxTiO3, Transmittance, Reflectance, Optical bandgap AR coating.

Submitted at: March 5, 2023
Accepted at: April 10, 2024


ALA’EDDIN A. SAIF, YEN CHIN TEH, Optical properties and bandgap analysis of multilayer sol-gel Ba1-xGdxTiO3 thin films for AR coating application, Journal of Optoelectronics and Advanced Materials Vol. 26, Iss. 3-4, pp. 122-128 (2024)