Design and evaluation of a Spirulina-based bio-layer as an infrared absorber to improve the power (I-V) performance of solar cells at high temperatures

Abstract In this experimental study, the optical and dielectric characteristics of Spirulina platensis were investigated to explore its potential in clean energy technologies. To characterize and evaluate the optical and electro-optical parameters of this microalga, a set of analytical techniques, including field emission scanning electron microscopy (FE - SEM), diffuse reflectance spectroscopy (UV - DRS), and Fourier transform infrared spectroscopy (FT - IR), was employed. The FE - SEM imaging of the S. platensis powder sample revealed a wide particle size distribution, ranging from 13 nm to 16 μm. The key optical parameters, including the refractive index (n), extinction coefficient (k), absorption coefficient (α), real and imaginary parts of the dielectric constant (ε₁ and ε₂), and optical conductivity (σ₁ and σ₂), were extracted from UV - DRS measurements in the 250 – 680 nm wavelength range using the Kubelka-Munk function and the Kramers – Kronig (K.K) relations. The optical band gap is found to be 2.34 eV. The FT - IR analysis extended the investigation into the infrared region, revealing strong optical absorption by S. platensis , highlighting its potential for thermal energy capture and energy management. According to these results, the current - voltage (I - V) performance of a solar cell was evaluated by applying S. platensis bio - layers of varying thicknesses under controlled temperature conditions. Two light sources, infrared and visible, were employed. Notably, in high - temperature environments such as desert regions, where ambient temperatures exceed 50 °C and typically degrade solar cell efficiency, the S. Platensis bio - layer acted as an optical filter, contributing to the stabilization of I - V performance. Overall, the findings underscore the potential of S. platensis to enhance solar energy applications through its distinctive optical and dielectric properties.