CAREER: Microwave-Assisted Ionic Liquid Etching of Colloidal III-V Semiconductor Nanocrystals

Kansas State University, Manhattan KS

Investigators

Abstract

Semiconductors, which comprise a class of solid materials with electrical conductivity intermediate between that of an insulator and that of a conductor, form the basic components of electronic circuits, light emitting diodes and sensor devices. Professor McLaurin employs microwaves to develop methods for semiconductor synthesis with the goal of more efficiently producing safer, superior nanocrystal (NC) materials known as quantum dots. Despite existing for more than 20 years, quantum dots are dominated by toxic heavy metal components and inefficient production methods. Dr. McLaurin's method of microwave-assisted ionic liquid (MAIL) etching provides a unique, reproducible approach for the production of high quality NC materials, such as indium phosphide (InP), that avoids toxic heavy metals and inefficient production methods. Broader impacts of the research are apparent in environmental and energy technology gains. High-quality InP NCs open up avenues for applications in energy-efficient lighting and low-cost solar cells, helping address current uncertainties in the global energy landscape. The absence of toxic heavy metals also highlights additional possibilities for using these materials in biological sensing and imaging. Dr. McLaurin provides broader educational impacts in her laboratory and demonstration modules designed for middle, high school, and undergraduate students. Partnership with the Kansas Louis Stokes Alliance for Minority Participation ensures broad diversity in her student base. Microwave ovens are a well-established home appliance, providing a good introduction to students of all ages. These simple microwave-based experiments relevant to nanotechnology and renewable energy applications offer hands-on experience with technologies central to our economy, ensuring future generations have relevant skills to be competitive in our global job environment. This award by the Macromolecular, Supramolecular and Nanochemistry (MSN) Program supports the research program of Professor Emily McLaurin at Kansas State University (KSU) to devise mechanisms of semiconductor nanocrystal (NC) etching, and obtain new protocols for acquiring NCs with specific properties. Results from this research improve the scientific value of microwave-assisted syntheses of colloidal toxic heavy metal (Pb, Cd, Hg)-free NCs through development of new methodologies and by detailing mechanistic aspects of the reactions that explain observed advantages over conventional syntheses. Microwave-assisted ionic liquid (MAIL) etching provides access to new reaction space variables, including unique, reproducible pathways for production of high quality NCs by balancing in situ etching with NC growth. Broader impacts of the research are apparent in environmental and energy technology gains. Mechanistic studies of etching aid in obtaining InP NCs with tunable properties, which can transform the area of colloidal semiconductor NCs synthesis by demonstrating the utility and advantages of microwave-assisted methods. Information about the systems studied, including the etching mechanisms, is readily applicable to other materials. Dr. McLaurin provides broader educational impacts in her laboratory and demonstration modules designed for middle, high school, and undergraduate students. Including more women and underrepresented minorities in science and engineering disciplines is key to attracting new talent to STEM fields. Dr. McLaurin tackles this challenge through the design of accessible, interesting lab activities for the KSU summer programs and their integration with curriculum at the undergraduate (4-year and community college) levels. Modules integrating nanomaterials with microwave chemistry and renewable energy applications combine fundamental scientific knowledge with real-world applications creating a meaningful educational experience.