Intraband Exciton Dynamics of n-Doped Silver Selenide Quantum Dots

AgxSe (x > 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(e)-1P(e)). 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 AgxSe is therefore essential for the assessment and successful implementation of this material platform in devices. We, herein, investigate the carrier dynamics of AgxSe 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 AgxSe CQDs and accelerates when the Fermi energy (E-F) level approaches the 1Pe state. The calculated intraband Auger coefficients (C-A) are measured to be on the order of similar to 10(-28) cm(6) s(-1), significantly larger compared to analogous n-doped HgS/Se CQDs.