Intraband Exciton\nDynamics of n‑Doped Silver\nSelenide Quantum Dots

Ag<sub><i>x</i></sub>Se (<i>x</i> > 2) colloidal\nquantum dots (CQDs) have recently emerged as a promising environmentally\nfriendly material contender for mid- and long-wave infrared optoelectronics,\nleveraging their intraband transition (1S<sub>e</sub>-1P<sub>e</sub>). However, multicarrier interactions in CQDs, particularly Auger\nrecombination, have profound implications on the optoelectronic properties\nof the materials and their potential in device applications. Understanding\nthe intraband excited-state dynamics in n-doped Ag<sub><i>x</i></sub>Se is therefore essential for the assessment and successful\nimplementation of this material platform in devices. We, herein, investigate\nthe carrier dynamics of Ag<sub><i>x</i></sub>Se in both\nsolution and thin-film states using a femtosecond mid-infrared transient\nabsorption spectrometer. Our observations reveal that the multicarrier\nAuger 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\nintraband Auger coefficients (<i>C</i><sub>A</sub>) are\nmeasured to be on the order of ∼10<sup>–28</sup> cm<sup>6</sup> s<sup>–1</sup>, significantly larger compared to analogous\nn-doped HgS/Se CQDs.