MRSEC Program Overview

Welcome to the internet hub of the Materials Research Science and Engineering Centers (MRSEC). This website provides organized information and resources at the various MRSECs for the international scientific, industrial, and educational materials research and development communities.

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Program Highlights

June 10, 2016

Red, Yellow, Green, and Blue Lasing Using Colloidal Quantum Wells

There is an abiding interest in using nanocrystals as laser gain media due to their tunable emission wavelengths, low cost, and solution processability. However, it has been proven difficult to achieve low lasing thresholds suitable for practical applicatons. MRSEC members Engel and Talapin showed that colloidal semiconductor nanoplatelets (NPLs) with electronic structure of quantum wells can produce optical gain and lase in the red, yellow, green, and blue regions of the visible spectrum with low thresholds and high gains, both a significant improvement over colloidal quantum dots. The lasing color is dictated solely by the NPL thickness while lateral dimension of the NPLs do not affect either the lasing thresholds or gain saturation levels. This observation highlights the qualitative difference of multiexciton dynamics in CdSe NPLs and other quantum-confined CdSe materials, such as quantum dots and rods.

June 10, 2016

Persistent Optical Gating of a Topological Insulator

An inter-MRSEC collaboration between the University of Chicago and the Pennsylvania State University led to the discovery of a new technique that enables bidirectional control of the chemical potential in a topological insulator (TI). A central challenge with these materials is to reliably tune the chemical potential of their electrons with respect to the Dirac point and the bulk bands, thereby hindering research and potential applications. This all-optical effect is persistent and allows for direct patterning and imaging of p-n junctions.