Interfacial engineering of hybrid heterojunction PV devices for the next generation lightweight, flexible, and low-cost solar modules

Abstract

This dissertation aims to develop a more complete framework for understanding the behavior of silicon-organic hybrid electronics, focusing on the development of high-performance hybrid heterojunction photovoltaic (hybrid HJT PV) devices based on thin silicon substrates and PEDOT:PSS as a hole-selective contact. Despite recent advancements in the field of organic and hybrid electronics, the behavior of these devices and their rapid degradation under ambient conditions remains poorly understood. Nevertheless, this technology remains highly promising for the next generation of flexible and hybrid electronics, due to the additional mechanical resilience provided to the thin substrates by the polymer films. Many aspects of this hybrid system have been investigated previously, which is why the scope of this dissertation is limited to: (1) Developing a more comprehensive theoretical framework of understanding the behavior and rapid degradation of hybrid PV devices under ambient conditions. (2) Developing strategies for empirically optimizing the performance of these devices and identifying the major shortcomings of the current processing techniques. (3) Understanding the role of the buried hybrid interface and the development of interfacial oxide between the silicon substrate and the organic film in the performance and degradation of the devices. (4) Identifying and testing alternative processing techniques to address the major challenges identified. ☐ The broader impact/commercial potential of the work presented in this dissertation is to enable photovoltaic deployment on water rather than just on land. The growth of solar photovoltaic energy has highlighted the increasing problem of competing land use, scarcity, and cost. Floating photovoltaics have emerged as a solution to this problem; deploying solar modules on existing bodies of water lessens the need for land-based installations. However, the high cost has inhibited growth of this renewable energy source. This project advances a new system that is lighter and cheaper. Furthermore, the modules are fabricated with non-toxic and environmentally friendly materials, mitigating the risk posed by other novel photovoltaic technologies of contaminating the bodies of water. ☐ The work presented here advances the development of lower cost lightweight alternatives for solar photovoltaic generation. This hybrid photovoltaic technology combines innovative polymer science with silicon, the most abundant and significant photovoltaic material in use today, to provide cheaper, lighter, and more efficient flexible modules. Recent computer model simulations indicate that the use an alternative polymer deposition method (oxidative chemical vapor deposition) coupled with an optimized surface treatment of silicon will enable the power efficiencies to exceed 20%. Furthermore, this hybrid approach allows the polymer to mechanically support the brittle silicon substrate, enabling the fabrication of flexible modules (to address wind load) encapsulated by plastic films rather than glass panels.