Efficiency Enhancement and Sustainability Analysis of Lead-Free Hybrid Perovskite Tandem Solar Cells

Abstract

This thesis explores advancements in perovskite solar cells (PSCs), with a primary focus on developing lead-free alternatives and tandem solar cells (TSCs) to address the environmental concerns associated with lead-based perovskites. The research begins by underscoring the critical role of photovoltaics (PV) in addressing global environmental challenges and provides a comparative analysis of various PV technologies and their life cycle assessment (LCA) parameters. Emphasis is placed on the unique optoelectronic properties of organic-inorganic hybrid perovskites (OIHPs) that enable high-efficiency PV cells, along with their limitations and potential strategies to mitigate these issues. This background sets the stage for a focused exploration of non-toxic OIHPs, specifically tin-based PSCs, and introduces the potential benefits of plasmonics and tandem structures for enhancing performance and stability. A thorough review of literature follows, covering the fabrication, simulation, and LCA of PSCs, with a particular focus on the progress made in lead-free variants, especially those based on tin. It presents experimental studies involving spin-coated tin perovskite thin films, identifying optimal conditions for improved power conversion efficiency (PCE) and stability. Furthermore, simulation studies using 2D-TCAD software illustrate the impact of integrating plasmonics, revealing substantial enhancements in photocurrent density and overall PCE. The thesis also incorporates LCA evaluations to assess the sustainability of PSCs incorporating advanced materials such as silver nanoparticles. For TSCs, the research explores the configurations using formamidinium tin iodide (FASnI3) paired with high-bandgap semiconductors, using the transfer matrix method (TMM) for optimizing multi-layer solar cell structures. Novel optimization approaches are introduced and assessed for their effectiveness in reducing parasitic losses, reflection losses, and achieving higher photocurrent density. The work extends to a combined optical and electrical analysis using 2D-TCAD simulations to refine active layer thickness and interlayer performance, showcasing methods for calculating energy densities under varying solar conditions.