Fabrication & characterization of perovskite solar cells and modules via manufacturing techniques

Organic-inorganic halide perovskite solar cells (PSCs) have recently sparked a lot of interest in academia and industry, as seen by the rising number of articles in the field. Despite the booming power conversion efficiencies, the commercialization of PSCs is impending. The primary bottlenecks are the relatively lower stabilities when compared to their silicon counterparts and lack of knowledge to transfer skills from lab-scale techniques to industrially manufacturable techniques. This doctoral thesis focusses on the development of materials, and novel device architectures for perovskite solar cells and modules on both rigid and flexible substrates for energy harvesting. Chapter 1 of this document addresses the need for renewable energy resources, focusing on the role of photovoltaic (PV) technologies in the global energy transformation. It highlights the implications of climate change and the increasing demand for sustainable energy sources. Overall, Chapter 1 provides a comprehensive overview of the importance of renewable energy and the potential of PSCs in addressing the world's energy needs in a sustainable manner. Chapter 2 explains solar cells and their potential in the global energy sector. We introduce the concept of organic semiconductors and solar cells. The operation mechanism of these solar cells is discussed, as well as how they are classified. Following that, recent development in materials and device architecture for PSCs is discussed, with a particular emphasis on upscaling process details and printing techniques; a detailed explanation of laser processing of PSMs is presented. Part of this work has been included in the paper “Low-Temperature-Processed Stable Perovskite Solar Cells and Modules: A Comprehensive Review” submitted as first author in the Advanced Energy Materials Journal by Wiley Online Library (available at https://doi.org/10.1002/aenm.202103534.) Chapter 3 of the dissertation focuses on the design of stable perovskite solar modules (PSMs) with an emphasis on using industrial sputtering techniques to improve stability. The chapter highlights the importance of stability in PSMs and the need to transfer lab-scale techniques to industrially manufacturable processes. The main objective is to improve the stability of PSCs and PSMs by employing a cell architecture that includes a sputtered indium-tin oxide (ITO) buffer layer between the metal and transport layers. The chapter describes the optimization of various parameters in the sputtering process to ensure high stability and retained power conversion efficiencies. These parameters include ITO layer thickness, target power density, and working pressure. The chapter also demonstrates fabrication of mini-module structures and the use of laser (P1, P2, P3) parameters to interconnect the cells. Overall, This work demonstrate the utilization and optimization of industrial manufacturing techniques such as radio-frequency sputter and nano-second laser to achieve stability and high efficiency in PSCs & PSMs. The work presented in this chapter has been published in the ACS Applied Materials & Interfaces journal. (available at https://doi.org/10.1021/acsami.2c10251) Chapter 4 discusses the improvement of the power conversion efficiencies of PSCs, with a focus on additive engineering. A combination of additives inside the perovskite ink were investigated: ionic liquids 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4), alkylamine ligands Oleylamine (OAm) and a reducing agent Benzylhydrazine hydrochloride (BHC). How the combination of these additives helps to improve efficiencies of devices by over 20% and stabilities beyond 1000 hours are also discussed. Further a universal nature of this approach is displayed by employing in other robust perovskite compositions leading to impressive stability both under light soaking and under 85°C. A part of this work has been published in the journal Nano Energy as a co-author (available at https://doi.org/10.1016/j.nanoen.2023.108268) . Chapter 5 details the comparison of various buffer layers which are compatible for the ITO barrier layer. Here, various inks of zinc oxide (ZnO), aluminum-doped zinc oxide (AZO) and tin oxide (SnO2) with varying work-functions and solvents have been investigated. In particular, the solvent interaction with beneath layers has also been tested. At least one of the inks in a variety of inks of each of the nanoparticle oxides are shown to be compatible with ITO. Critically, it is found that a few of the metal oxides inks can be deposited with static deposition, making it compatible with large-area blade/slot-die coating. Further, to demonstrate the effectiveness of the layer obtained, the solution-processed oxide layer is compared with atomic layer deposition. Part of this chapter is about to be submitted to a scientific journal as co-author with the tentative title “Comparison of Solution-Processed Buffer Layers for Semi-transparent Perovskite Solar Cells”. Chapter 6 This chapter explores the transition from spin-coating to slot-die coating for flexible perovskite solar cells (PSCs), addressing scalability and performance challenges. It emphasizes the importance of achieving uniform and high-quality perovskite films for efficient PSCs, necessitating the exploration of alternative coating techniques. Key highlights include the design of a solvent system that is compatible with both spin-coating and slot-die coating processed in air. We optimized perovskite film crystallization and ink formulation and analysed morphology and additives' effects on device performance. The study also discusses the optimization of bladecoating and slot-die coating parameters to achieve uniform thickness and defect-free coatings. Overall, the chapter provides insights into scalable coating techniques for PSCs, contributing to the advancement of large-scale manufacturing processes for efficient and commercially viable solar modules. This chapter will be prepared and revised, and it will be included in a scientific journal as first author with the tentative title “All Slot-die Coated Air-processed Flexible Inverted Perovskite Solar Cells.” Chapter 7 highlights the major results obtained in this research, as well as their significance towards commercialization. These findings raise the possibility of developing more controlled perovskites for fully commercialization of perovskite solar cells. Further, the dissertation concludes with numerous proposals for future activities and additional prospective advancements.