RII Track-4:NSF: Understanding Perovskite Solar Cell Passivation at The Level of Organic Functional Groups through Ultrafast Spectroscopy

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This EPSCoR Research Infrastructure Improvement Track-4: EPSCoR Research Fellows project provides a fellowship to an Assistant Professor at Jackson State University (JSU), a Historically Black Colleges and Universities (HBCU). The project will also support a JSU graduate student with a training opportunity in ultrafast spectroscopy. The principal investigator (PI) and the graduate student will have a six-month visit at Emory University to extend the expertise to ultrafast spectroscopy for the JSU research community. JSU researchers will learn hands-on skills, measurement principles, data collection, data analysis, and data plotting at Lian group to fully understand this advanced technique of ultrafast spectroscopy. The proposed ultrafast spectroscopy skills and knowledge could only be obtained through an extended on-site visit due to the complexity and the knowledge depth, which is uniquely supported by this NSF EPSCoR RII Track-4 program. With this new technique, the research capacity of the JSU will be significantly enhanced in terms of a better understanding of the perovskite solar cells. Through this project, PI’s career trajectory can be positively impacted and potentially transformed from solar cell device engineering to fundamental understanding of interfaces of optoelectronic devices. The close collaboration between JSU and Emory through this project also benefits other research fields at JSU such as nanomaterials, transistors, batteries, and biomaterials. This NSF EPSCoR RII Track-4 fellowship project provides a unique opportunity to support the PI and one graduate student at JSU to visit Emory University to extend their expertise in ultrafast spectroscopy to understand the charge transfer process affected by organic functional groups (OFGs) at the interfaces in the perovskite solar cells (PSCs). The research goals of this project include: 1) probing the relationship between the types of OFGs and the types of perovskite film defects and investigating the charge transport affected by the types of OFGs; and 2) studying the detailed effects of charge separation, charge recombination, and charge transfer process by fourteen commonly used OFGs in the passivation of the perovskite films. The fourteen OFGs in PSCs will be investigated by passivation of three common specific types of defects of perovskite films such as organic component vacancies, metal vacancies, and iodine vacancies using visible, femtosecond, and nanosecond transient absorption spectra, and time-resolved photoluminescence in nanoseconds, femtoseconds, and picoseconds. This project will provide a fundamental understanding of the relationship between the types of defects of the perovskite films and the types of passivation OFGs to understand the passivation procedures and OFG selection based on the defects of the perovskite films. The influence of different OFGs on the charge separation, charge recombination, and charge transfer processes in the devices will also be demonstrated in this project, which will provide new insights into the charge transport process at the interfaces and a new understanding of the device performance by the interface of the devices via OFG passivation.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.