2018 Mayer Scholarship Recipient

Scott Melis cocrystals formed using phenothiazine (PTZ) and TCNQ as two coformers

Posted in News Story

The Department of Physics is pleased to announce that Scott Melis is the recipient of the 2018 Professor Walter G. Mayer Endowed Scholarship, which supports a graduate student pursuing a Ph.D. in experimental physics.

Scott’s project involves studying the controlled formation of charge transfer cocrystals to better understand how to apply their useful semiconducting electrical properties. So far, Scott has focused on cocrystals formed using phenothiazine (PTZ) and TCNQ as two coformers.  Fairly aligned PTZ:TCNQ cocrystals that are several hundred microns long are able to be grown on a substrate using a controlled evaporative self-assembly (CESA) technique.  This method involves dropcasting a solution containing both coformers onto a glass rod on top of a substrate. The surface tension between the solvent and the rod guides the direction of evaporation and thus, the growth direction of the crystals.

So far, Scott has demonstrated that working field effect transistors can be made out of PTZ:TCNQ cocrystals.  Crystals that were grown on bottom contact bottom gate electrodes were shown to be easily fabricated but measured values for the electron mobility of these devices were lower than expected.  However, new top contact devices have been produced and appear to be more promising despite still being studied.  Going forward, Scott hopes to look more at the electrical properties of cocrystals formed out of both these and similar materials in addition to further exploring the parameters that control their nucleation and growth.