Terahertz Excitonics in Carbon Nanotubes: Exciton Autoionization and Multiplication.

ABSTRACT: Excitons play major roles in optical processes in modern semiconductors, such as single-wall carbon nanotubes (CNTs), transition metal dichalcogenides, and 2D perovskite quantum wells. They possess extremely large binding energies (>100 meV), dominating absorption and emission spectra even at high temperatures. The large binding energies imply that they are stable, that is, hard to ionize, rendering them seemingly unsuited for optoelectronic devices that require mobile charge carriers, especially terahertz emitters and solar cells. Here, we have conducted terahertz emission and photocurrent studies on films of aligned single-chirality semiconducting CNTs and find that excitons autoionize, i.e., spontaneously dissociate into electrons and holes. This process naturally occurs ultrafast (<1 p

SUBMITTER: Bagsican FRG 

PROVIDER: S-EPMC7227006 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature