Studies on UV/Visible Absorption and IR Transmission Characteristics of Cu²⁺ Ion in a Soda-Magnesia-Lime-Silica Glass for Solar Application

ABSTRACT

The aim of this investigation is to study the UV/Visible absorption and infra-red transmission characteristics due to Cu⁺/Cu²⁺ redox in silica glass. The glass composition 18Na₂O-2MgO-8CaO-72SiO₂ (mol%) containing different concentrations of CuO were prepared by melting route. The optical absorption spectra of the glasses were recorded on an UV/Visible/NIR spectrophotometer in the wavelength range of 200-1100 nm. The linear absorption coefficient was found to be around 7.60 cm^–1 per wt% of CuO in the glass samples. The Cu²⁺ band was attributed to spin allowed transition from ²E_g →²T_2g level in the glass and the applicability of Urbach’s rule was tested for Cu⁺ ion. It was found that optical band gap for Cu⁺ was 4.03 eV and its band width was 0.43 eV in the glass. The oscillator strength of the Cu⁺ ion band (ƒ_abs) in the glass was reported. The absorption and transmission characteristics of glass containing Cu⁺ and Cu²⁺ ions showed a decrease in absorption coefficient of Cu²⁺ beyond red spectral region. This dictates that glass containing copper ions can be used for IR transmitting purpose and can convert the solar energy into electrical energy for photovoltaic applications.

GRAPHICAL ABSTRACT

Keywords:

• UV/Visible/NIR spectra
• Cu²⁺ ion
• Silicate glass
• Linear absorption coefficient
• Solar photovoltaic application