Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Creutz, Sidney

Committee Member

Gangishetty, Mahesh

Committee Member

Wipf, David

Committee Member

Munoz, Miguel

Date of Degree

5-12-2023

Document Type

Graduate Thesis - Open Access

Major

Chemistry

Degree Name

Master of Science (M.S.)

College

College of Arts and Sciences

Department

Department of Chemistry

Abstract

Semiconductors play an integral part in modern society. From computing to LEDs their use is ubiquitous, and no field is more reliant on them than that of power generation. Current political movements have seen a push to decrease reliance on traditional forms of power generation, which relies on fossil fuels, to renewable sources such as solar power. However, current commercial solar panels, based on silicon, are lacking in efficiency, only reaching between 18% and 22% efficiency.1 In recent years, materials called perovskites have been garnering significant attention as possible replacements for silicon cells due to their favorable optoelectronic properties.2 However, the most widely researched perovskite, lead-halide perovskites, have obvious problems with stability.3 This instability, coupled with their use of lead, can lead to the leaching of lead into the environment. Several ideas have been proposed to mitigate this problem including better encapsulation of the lead halide perovskite, substitution of lead with other elements, and non-perovskite structures. In this work, we explore the synthesis and ion exchange of ternary bismuth chalcogenides with the goal of creating a split-anion perovskite.4 To accomplish this, we first synthesize inorganic bismuth chalcogenide ABiS2 nanocrystals, where A is a +1 cation. Following the synthesis of these nanocrystals, we suspend them in solution and add trimethylsilyliodide (TMSI) which reacts with the sulfur in the nanocrystal replacing it with iodide. By modulating the amount of TMSI in the reaction, we believe we can create a perovskite-like nanocrystal that incorporates nanocrystals with anions of differing oxidation states, enabling a greater variety of elements that could adopt the perovskite phase. In this work we focused on crystals where A = Ag+ and Cs+, with which we were able to demonstrate the ion exchange.

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