Organic solar cells and printed supercapacitors: realization , characterization and applications

This thesis investigates the development of materials and architectures for organic photovoltaic (OPV) devices and their integration with energy storage systems on flexible substrates, aimed at enhancing energy harvesting and storage capabilities in both indoor and outdoor environments. By addressing the challenges related to non-conventional substrates, the research explores the realization of OPV on paper as energy harvesting device and demonstrates significant advancements in fabrication of interdigitated supercapacitors on paper as energy storage system. The integration of these components results in the creation of a flexible hybrid photosupercapacitor as a power pack. In Chapter 1, we introduce the current progress in OPVs, and focusing on their potential to meet the escalating global demand for renewable energy solutions. This chapter reviews advancements in organic solar cells, particularly highlighting their lightweight, flexible properties and lower environmental impact, which make them suitable for various applications including portable and indoor technologies. Additionally, the chapter delves into the developments in supercapacitors, highlighting various types with a particular emphasis on flexible supercapacitors. Chapter 2 provides a comprehensive overview of the integration of solar cells with supercapacitors. This hybrid system combines the immediate energy generation capabilities of solar cells with the rapid charge and discharge properties of supercapacitors, effectively addressing the intermittency issues inherent in solar power. This integration ensures a consistent energy supply, crucial for applications requiring reliable power. In Chapter 3, we discuss the development of sustainable, solution-based processing techniques for fabricating OPVs, emphasizing the transition from metal evaporation to spin coating and spraying. By solution depositing HTL Solar as the hole transport layer, we surpassed the performance of evaporated MoO3, achieving a power conversion efficiency (PCE) of 7.49%. This chapter underscores the shift towards more scalable and environmentally friendly fabrication processes. The use of paper substrates, despite challenges, offers environmental benefits and cost-effectiveness. Additionally, interdigitated supercapacitors on cellulose-based substrates show enhanced performance and align with sustainability goals. This study underscores the shift towards scalable and eco-friendly fabrication processes in OPVs and supercapacitors. Chapter 4 examines the impact of interfacial layers on OPV performance under various lighting conditions. The study reveals that interfacial layers like polylysine and polyethyleneimine ethoxylated (PEIE) significantly enhance device efficiency, with polylysine showing superior performance under 1-sun illumination and PEIE excelling under indoor light. These findings highlight the importance of selecting appropriate interfacial layers for optimizing OPV devices for different lighting conditions. This chapter has been published as the first author with the title "Effect of PEIE and Polylysine as Interfacial Layers on the Performance of Air-Processed Organic Solar Cells under Both Indoor and 1 Sun Conditions," Sustainable Energy Fuels, 2023 (available at https://doi.org/10.1039/D3SE00242J). Chapter 5 introduces an innovative hybrid device that integrates a flexible perovskite solar module on PET with a carbon screen-printed supercapacitor on paper. This all-flexible photosupercapacitor demonstrates remarkable stability, a wide potential window, and high efficiency across various lighting conditions. The hybrid device's ability to function effectively under both outdoor and indoor environments makes it suitable for portable, indoor, and wearable electronics. This chapter has been submitted as first author to the journal of “Advance Functional Materials” with the title ““Integration of a Paper-Based Supercapacitor and Flexible Perovskite Mini-Module: Towards Self-Powered Portable and Wearable Electronics” submitted to Advanced Energy Materials”. Finally, Chapter 6 summarizes the main results achieved in this work and their implications in the field of photovoltaic supercapacitors and their integration. It outlines suggestions for future research, emphasizing the need for further optimization of material properties and device architectures to enhance performance, stability, and sustainability. This chapter highlights the potential for OPVs and hybrid energy systems to provide efficient, flexible, and sustainable energy solutions for a wide range of applications.