Date on Master's Thesis/Doctoral Dissertation

12-2023

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Chemistry

Degree Program

Chemistry, PhD

Committee Chair

Grapperhaus, Craig

Committee Member

Ramezanipour, Farshid

Committee Member

Thompson, Lee

Committee Member

Druffel, Thad

Author's Keywords

Nanoparticles; solution processing; Perovskite solar cells; nickel oxide; tin oxide; charge transport materials

Abstract

Perovskite solar cells (PSCs) are a promising alternative to silicon-based photovoltaics. However, PSCs face several challenges due to shortcomings in their stability, module efficiency, and scaled production. Although PSCs is still a young field of research, significant attention has been given to demonstrating power conversion efficiencies that are on par with traditional silicon. With that target reached, converting the laboratory demonstration into practical materials to increase access and abundance of solar energy are among the next large targets for the field. This comes with material challenges for perovskite and their companion charge transport layers (CTLs). Among the charge transport materials often used, NiOx nanoparticles have stood out as a leading material for an efficient, stable, and scalable CTL. In this dissertation the scalable deposition of NiOx is addressed through compositional design and solvent engineering. Two NiOx nanoparticle formulations have been developed and deposited by scalable coating methods to fabricate functional PSC devices. Inks were analyzed by zeta potential, TGA, and theoretical solvent analysis. Film quality was characterized by SEM and J-V analysis. Using compositional design, NiOx nanoparticles were successfully suspended in a nonpolar solvent system. It was found that the addition of large ligands was unnecessary for particle stabilization in a chlorobenzene-based solution, and that the presence of these ligands significantly obstructed charge extraction. Through further work with solvent engineering, a water based NiOx suspension that did not require additional ligands was developed. This NiOx formulation allowed for rapid large area coating on both blade coating and slot die coating systems. Utilizing intense pulsed light (IPL) annealing, processing time was further decreased with an increase in device performance. When used in a slot die coating system with IPL we were able produce a champion device PCE of 12.23%. In this dissertation the stability of the novel SnO2/Ag interface was also explored. Perovskite ion migration is a leading source of degradation with the formation of AgI a common by product. A series of imidazoles were evaluated to identify structural features that contribute to an effective blocking layer. It was found that imidazoles with conjugated planer systems and hydrogen bonding heteroatoms were able to prevent ion migration and retain device performance

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