Eco-Friendly All-Layer Green Solvent Efficient Perovskite Solar Cells

Perovskite solar cells (PSCs) have made significant advancements, becoming great candidate for the next-generation photovoltaics. They offer notable power conversion efficiencies (PCEs) of up to 26.1%, high flexibility, and relatively low manufacturing costs. However, several key challenges prevent their widespread commercial adoption, including toxicity of the materials and chemicals used in their production. Most high-efficiency PSCs currently rely on the toxic solvent N,N-dimethylformamide (DMF), which is unsuitable for large-scale production. While many studies have addressed stability and scalability, less progress has been made in identifying non-toxic, green solvents for PSC production. This study aims to address this gap by identifying and utilizing green solvents for a more sustainable approach to PSC production.<br/>This study focused on the utilization of gamma-valerolactone (GVL), a biodegradable and non-toxic polar aprotic solvent. The environmental friendliness and potential for dissolving perovskite precursors of GVL make it a promising candidate. However, GVL faces solubility challenges with critical components like lead iodide (PbI₂) and formamidinium iodide (FAI), which are necessary for high-efficiency perovskite films. This research investigates the use of methylammonium chloride (MACl) to enhance the solubility of FAI and PbI₂ in GVL-based solutions, facilitating the formation of high-quality perovskite films. Our results show that MACl not only resolves solubility issues but also significantly improves the morphology, optical, and electrical properties of the films. MACl promotes the formation of the α-phase in FAPbI₃, known for its superior photovoltaic performance over the δ-phase, which dominates without proper processing or additives.<br/>We thoroughly characterized the impact of MACl on perovskite films using various analytical techniques, including Scanning Electron Microscopy (SEM) for morphology, X-Ray Diffraction (XRD) for phase composition, and photoluminescence (PL) and UV-visible spectroscopy for optical properties. Films with higher MACl concentrations exhibited larger grain sizes, reduced defect density at grain boundaries, and enhanced phase stability, all contributing to improved device performance. By leveraging the benefits of GVL and MACl, we developed an all-layer green solvent PSC fabrication process, achieving a PCE of 20.6%. When comparing the normalized performance by dividing the PCE by the green solvent index, the GVL-based all-layer green solvent PSC significantly outperformed other high-efficiency PSCs, highlighting the potential of GVL and MACl as viable alternatives for environmentally friendly PSC production.<br/>In summary, this study introduces a sustainable PSC fabrication method that maintains high efficiency and stability. By addressing solubility challenges of GVL using MACl as an additive, we demonstrate the feasibility of producing high-performance, eco-friendly PSCs. This work advances green chemistry in photovoltaics and sets a foundation for future research aimed at reducing the environmental impact of PSC manufacturing.