CAREER: Design of Thermomechanically Robust Metal Halide Perovskite Photovoltaic Devices

One scientific question that is key to all engineering research is "What are the key criteria to make a long-lasting material, device, and system?" The answer to this question can often be better understood through the lens of mechanical reliability. Whether studying semiconductor microelectronics, renewable energy harvesting and storage technologies, other optoelectronic devices such as light emitting diodes (LEDs), detectors, lasers, or even biodevices, reliability is often governed by the interaction of environmental and mechanical stress parameters. Metal halide perovskites (MHPs) are the premier next-generation photovoltaic (PV) technology based on low-cost and high-performance applications in PV, LEDs, and photo/X-ray detectors. The problem is that MHPs have been identified as among the most mechanically fragile of any optoelectronic device, but the mechanical properties of MHPs have been largely overlooked. The integrated research and educational resources explore the link between mechanical properties and operational stability in PV devices to enable manufacturability of MHP technology through involvement of underserved populations. The "Perovskite Solar Cell 101" outreach effort to local community colleges and tribal schools will include women and Indigenous students. The addition of free online resources on PVEducation, the world's largest online and free semiconductor textbook, is aimed at reaching a worldwide audience. A graduate peer mentoring program is designed to welcome individuals of all backgrounds, particularly first-generation students who may have less familiarity with PhD program expectations. One key outcome that will be pursued is the development of a culture of inclusion through increasing support for Indigenous and women as well as their access to resources and opportunities in the solar and semiconductor industries. This culture of inclusion is defined as the pursuit of values promoting a sense of belonging for all individuals, recruiting people from a diversity of cultural backgrounds, and advancing inclusion initiatives toward systemic and institutional change. According to the International Energy Agency, the common failures observed in all PV modules are delamination, adhesion loss, junction box failure, and frame breakage. To this end, the thermomechanical measurements leveraged in this work were selected because they directly measure delamination and adhesion loss. There is a lack of understanding on the relationship of mechanical properties with degradation and how these properties evolve during operation. The central research objective is to answer the following question: "How can MHPs be designed for thermomechanical reliability that address the key failure mechanisms observed in the lab and the field?" The research objective will be studied through the following scientific questions: (1) What are the predominant thermomechanical-based failure mechanisms in the lab? (2) How can failures in the field be predicted by experiments in the lab? (3) How can more stable and reliable MHP devices be produced based on design criteria developed through the research? The central hypothesis is that in situ lab test data (through fracture, film stress, and ionic measurements) along with finite element modeling combined with analysis of field failures can elucidate the failure mechanisms and determine criteria for robust MHP device and module designs. When combined with the accelerated aging conditions enabled through control of humidity, heat, temperature, illumination, and bias during testing, these lab measurements that probe the synergistic effect of environmental and mechanical stressors aim to enable the development of accelerated test sequences that verify and validate MHP PV durability. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.