Carrier Multiplication in Quasi-1D Nanosystems: A Time-Dependent Density Functional Theory Study

Carrier multiplication (CM) is a fundamental process in the electronic excited state, which generates multi-excitons from a single-photon absorption. CM has been intensively investigated for photovoltaic applications, because it can improve optoelectronic devices efficiency. However, CM is rarely witnessed in conventional semiconductors, calling for an unconventional material enhancing the CM. Here, using real-time time-dependent density functional theory, we show that CM occurs in quasi-one-dimensional (1D) nanosystems derided from 2-dimensional van der Waals materials. The origin of CM in quasi-1D, i.e., releasing the constraints of the CM process, are different from that in 0D nanosystems, i.e., phonon bottleneck. The results provide the way to control the excited carrier dynamics and CM in nanosystems.