An ideal n-i-p perovskite solar cell employing a Pb free CH₃NH₃SnI₃ absorber layer was suggested and modelled. A comparative study for different electron transport materials has been performed for three devices keeping CuO hole transport material (HTL) constant. SCAPS-1D numerical simulator is used to quantify the effects of amphoteric defect based on CH₃NH₃SnI₃ absorber layer and the interface characteristics of both the electron transport layer (ETL) and hole transport layer (HTL). The study demonstrates that amphoteric defects in the absorber layer impact device performance significantly more than interface defects (IDL). The cell performed best at room temperature. Due to a reduction in V_oc, PCE decreases with temperature. Defect tolerance limit for IL1 is 10¹³ cm⁻³, 10¹⁶ cm⁻³ and 10¹² cm⁻³ for structures 1, 2 and 3 respectively. The defect tolerance limit for IL2 is 10¹⁴ cm⁻³. With the proposed device structure FTO/PCBM/CH₃NH₃SnI₃/CuO shows the maximum efficiency of 25.45% (V_oc = 0.97 V, J_sc = 35.19 mA/cm², FF = 74.38%), for the structure FTO/TiO₂/CH₃NH₃SnI₃/CuO the best PCE is obtained 26.92% (V_oc = 0.99 V, J_sc = 36.81 mA/cm², FF = 73.80%) and device structure of FTO/WO₃/CH₃NH₃SnI₃/CuO gives the maximum efficiency 24.57% (V_oc = 0.90 V, J_sc = 36.73 mA/cm², FF = 74.93%) under optimum conditions. Compared to others, the FTO/TiO₂/CH₃NH₃SnI₃/CuO system provides better performance and better defect tolerance capacity.

The solution casting technique is utilized to fabricate blank and CuO-doped polyvinyl alcohol/chitosan (PVA/CS) blends for eco-friendly applications. The structure and surface morphologies of prepared samples were explored by Fourier transform infrared (FT-IR) spectrophotometry and scanning electron microscopy (SEM), respectively. FT-IR analysis reveals the incorporation of CuO particles within the PVA/CS structure. SEM analysis exposes the well-dispersion of CuO particles in the host medium. The linear/nonlinear optical characteristics were found on the basis of UV-visible-NIR measurements. The transmittance of the PVA/CS decreases upon CuO increasing to 20.0 wt%. The optical bandgap (E_{g dir.}/E_{g ind.}) decreases from 5.38/4.67 eV (blank PVA/CS) to 3.72/3.12 eV (20.0 wt% CuO-PVA/CS). An obvious improvement in the optical constants of the PVA/CS blend is achieved by CuO doping. The Wemple-DiDomenico (WDD) and Sellmeier oscillator models were utilized to examine the CuO role dispersion behavior of the PVA/CS blend. The optical analysis shows clear enrichment of the optical parameters of the PVA/CS host. The novel findings in the current study nominate CuO-doped PVA/CS films for applications in linear/nonlinear optical devices.

Tungsten oxide (WO_x) thin films were synthesized through the RF magnetron sputtering method by varying the sputtering power from 30 W to 80 W. Different investigations have been conducted to evaluate the variation in different morphological, optical, and dielectric properties with the sputtering power and prove the possibility of using WO_x in optoelectronic applications. An Energy Dispersive X-ray (EDX), stylus profilometer, and atomic force microscope (AFM) have been used to investigate the dependency of morphological properties on sputtering power. Transmittance, absorbance, and reflectance of the films, investigated by Ultraviolet-Visible (UV-Vis) spectroscopy, have allowed for further determination of some necessary parameters, such as absorption coefficient, penetration depth, optical band energy gap, refractive index, extinction coefficient, dielectric parameters, a few types of loss parameters, etc. Variations in these parameters with the incident light spectrum have been closely analyzed. Some important parameters such as transmittance (above 80%), optical band energy gap (~3.7 eV), and refractive index (~2) ensure that as-grown WO_x films can be used in some optoelectronic applications, mainly in photovoltaic research. Furthermore, strong dependencies of all evaluated parameters on the sputtering power were found, which are to be of great use for developing the films with the required properties.