Intraband Exciton Dynamics of n-Doped Silver Selenide Quantum Dots.

Bera, Rajesh; Dosil, Miguel; Konstantatos, Gerasimos · Nano Lett · 2024

basic_science · Level V

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Abstract

Ag<sub><i>x</i></sub>Se (<i>x</i> > 2) colloidal quantum dots (CQDs) have recently emerged as a promising environmentally friendly material contender for mid- and long-wave infrared optoelectronics, leveraging their intraband transition (1S<sub>e</sub>-1P<sub>e</sub>). However, multicarrier interactions in CQDs, particularly Auger recombination, have profound implications on the optoelectronic properties of the materials and their potential in device applications. Understanding the intraband excited-state dynamics in n-doped Ag<sub><i>x</i></sub>Se is therefore essential for the assessment and successful implementation of this material platform in devices. We, herein, investigate the carrier dynamics of Ag<sub><i>x</i></sub>Se in both solution and thin-film states using a femtosecond mid-infrared transient absorption spectrometer. Our observations reveal that the multicarrier Auger process depends on the degree of doping in Ag<sub><i>x</i></sub>Se CQDs and accelerates when the Fermi energy (<i>E</i><sub>F</sub>) level approaches the 1P<sub>e</sub> state. The calculated intraband Auger coefficients (<i>C</i><sub>A</sub>) are measured to be on the order of ∼10<sup>-28</sup> cm<sup>6</sup> s<sup>-1</sup>, significantly larger compared to analogous n-doped HgS/Se CQDs.