Graduate Defense: Florent Muramutsa

Dissertation Information

Title:  Black Phosphorus Ink Formulation for Aerosol Jet Printing

Program: Doctor of Philosophy in Materials Science and Engineering

Advisor: Dr. David Estrada, Materials Science and Engineering and Electrical and Computer Engineering

Committee Members: Dr. Brian Jaques, Materials Science and Engineering; Dr. Paul Simmonds, Materials Science and Engineering; Dr. Harish Subbaraman, Electrical and Computer Engineering; and Dr. Joshua Wood, Materials Science and Engineering

Abstract

As the demand for data-driven technologies such as cloud computing, artificial intelligence, and the Internet of Things increases, the value of data centers rises. However, the cost of optoelectronic materials utilized in data centers continues to be high. This cost can be limiting in developing data centers for high-bandwidth and large-scale applications. In this dissertation, we investigated the potential of black phosphorus (BP) as a material for optoelectronic devices and aerosol jet printing (AJP) as a viable deposition method. AJP-compatible inks were synthesized by mixing liquid-phase exfoliated converted BP flakes with isopropanol, water, and 2-butanol solvents. We demonstrate that these inks can be printed on various surfaces, such as flexible polyimide, glass, conformal quartz tubes, pre-deposited graphene, and WS2. Using high-resolution transmission electron microscopy, we examined the relationship between BP’s microstructure and its electrical and optical properties. Using density gradient ultracentrifugation (DGU), we purified polydisperse converted-BP dispersions into monolayer dispersions to exploit the layer-dependent bandgap of BP. In addition, we demonstrated that cascade centrifugation and tangential flow filtration (TFF) could be used to generate larger quantities of purified samples. We show that combining cascade centrifugation and TFF is an effective solution processing method for BP inks by enabling purification, surfactant removal, solvent exchange, and dispersion concentration. Our results indicate that AJP-printed BP has the potential to function as an active material in optoelectronic devices.