Design and modeling of semi-transparent perovskite solar cells
2024
The consumption of renewable energy is rapidly increasing. Additionally, limited non-renewable resources are available. Therefore, continuous research efforts are being made to generate energy from renewable sources such as solar, water, wind, etc. Photovoltaic cells, particularly perovskite solar cells, have gained popularity due to ease of fabrication, cost-effectiveness, high absorption coefficient, controllable energy gap, high charge carrier mobility, excellent power conversion efficiency (PCE), etc. The recent generation of perovskite solar cells are semi-transparent. In such solar cells, metallic back contacts are replaced by transparent contacts such as transparent conducting oxide (TCO) and thus they are able to absorb the solar light from both front and back contacts. In this regard, the incident light flux is enhanced which results in a higher absorption and PCE. In this research, optical and electrical modeling of a semi-transparent perovskite solar cell with a transparent back contact has been conducted using the COMSOL software. Finite Element Method (FEM) was employed to calculate absorption, reflection, light transmission, and the generation rate of electron-hole pairs. Electrical analysis was performed using the semiconductor module, obtaining characteristics such as the current-voltage (J-V) curve and photovoltaic parameters including short-circuit current, open-circuit voltage, filling factor, and PCE of the propose structure. Validating the simulation results, a semi-transparent solar cell with a MoOx/ITO back contact achieved a PCE of 13.87%. Removing the MoOx buffer layer increased PCE to 96.13%. Therefore, a buffer-less structure with high PCE was introduced, offering advantages such as simplified fabrication steps, accelerated manufacturing processes, reduced material requirements, and cost-effectiveness. In the following, different back contact materials (ITO, IZO, IOH) were tested, with IOH exhibiting the best performance with a PCE of 31.14%. Additionally, applying Albedo light to the back contact increased PCE from 14.31% to 18.21%. To further enhance PCE by minimizing losses from Fresnel reflection, MgF2 anti-reflection layers with an optimal thickness of 80 (100) nm were applied on front (back) contacts. Results showed that adding these layers increased PCE to 19.69%. Consequently, incorporating anti-reflection layers on both sides of the contacts resulted in an 8% increase in PCE.