CAREER: Guiding automated synthesis of hybrid perovskites towards stability via knowledge of nanoscale ionic mechanisms

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Metal halide perovskites are a new class of hybrid materials with inorganic and organic components with the potential to revolutionize optoelectronic technologies. They have shown particular promise for the next generation of inexpensive, efficient solar cells. The primary limiting factor to widespread use of perovskites is that they are not stable in devices. This project will develop an understanding of the fundamental and specific properties of perovskites with an overarching goal of improved stability. This project will elucidate and describe the electrochemistry of these materials to inform development of new processes for manufacture of stable perovskites. This work is made possible by an innovative automated synthesis approach that allows for experimentation on a diverse range of novel compositions that would be difficult to identify and study otherwise. The PI will strive to increase interest and participation of women in materials science and engineering research careers through an active, project-based outreach program. This program will include individualized career awareness mentoring for high school students and undergraduates.Organic–inorganic halide perovskites (OIHP) have many qualities that are ideal for optoelectronic applications and are used to improve function and reduce cost of solar cells, photodetectors, and light-emitting diodes. The substantive hurdles to widespread, commercial use of OIHPs are their instability and low long-term performance. Precise control of ionic chemistry and understanding of how interfacial and surface chemistry affects function are essential to overcome these limitations. This project will measure and describe the underlying mechanisms that affect OIHP intrinsic stability to create predictive models that will inform design of durable materials. The three challenges related to the stability of OIHPs examined in this project are: 1) establish rapid guided automated combinatorial synthesis workflow for material discovery and optimization, 2) determine the role of ion chemistry via electrochemical gating experiments, and 3) describe the kinetics and thermodynamics of the interfacial electrochemical processes on the three-phase junctions. The project will employ microscopy techniques and imaging of in-operando devices to build a comprehensive understanding of the internal electrochemical functionality of OIHP systems, which would enable a path toward predictive modelling and optimization of processing. The proposed automated synthesis approach using rapid characterization and slow device testing will allow for navigation of the compositional and processing space of these materials. The project-based outreach program will integrate the physics of electronic and ionic charge transports with machine learning concepts for new research experiences for undergraduate and graduate students. Grade-level appropriate versions of these activities will be offered to interested female high school students to increase interest in and improve preparation for materials science careers for women and other groups underrepresented in STEM.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.