Project Description:

Lead sulfide (PbS) colloidal quantum dots (CQDs) are highly promising materials for next-generation optoelectronic devices, but accurate charge transport characterization remains a major hurdle, due to the common reliance on in-plane (lateral) measurements to describe transport in inherently out-of-plane (vertical) device structures such as solar cells. 

This project addresses this gap by conducting a comparative study of charge carrier mobility anisotropy in PbS CQD films, through the fabrication, testing, and evaluation of both vertical (VFET) and lateral (LFET) field-effect transistor architectures to compare out-of-plane versus in-plane transport.

We hypothesize that charge carrier mobility in PbS CQD films is anisotropic, with vertical transport potentially reduced relative to lateral transport due to structural defects and interface-related limitations in the CQD superlattice. Any observed anisotropy would highlight the critical need for precise film morphology control and interface engineering for optimizing the performance and predictive simulation of vertically structured CQD optoelectronic devices.

Project Photo:

Yijun Zhang (left) and Yarden Ben Hayon (right) each holding a quantum dot Vertical Field Effect Transistor, right before it was characterized.

Yarden Ben Hayon

Yijun Zhang

Sponsors: National Science Foundation, U.S. Department of Defense