Slow Auger Recombination in Ag2Se Colloidal Quantum Dots

Chen Liao; Luping Tang; Yunzhe Jia; Shaoling Sun; Haoran Yang; Jie Xu; Zixuan Gu

doi:10.1021/acs.nanolett.3c02770

Slow Auger Recombination in Ag₂Se Colloidal Quantum Dots

Nano Lett. 2023 Nov 8;23(21):9865-9871. doi: 10.1021/acs.nanolett.3c02770. Epub 2023 Oct 23.

Authors

Chen Liao¹, Luping Tang^{2

3}, Yunzhe Jia¹, Shaoling Sun⁴, Haoran Yang¹, Jie Xu¹, Zixuan Gu¹

Affiliations

¹ College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing 210023, China.
² College of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, China.
³ SEU-FEI Nano-Pico Center, Key Lab of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China.
⁴ Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, China.

PMID: 37871258
DOI: 10.1021/acs.nanolett.3c02770

Abstract

Efficient Auger recombination (AR) presents a significant challenge for the advancement of colloidal quantum dot (QD)-based devices involving multiexcitons. Here, the AR dynamics of near-infrared Ag₂Se QDs were studied through transient absorption experiments. As the QD radius increases from 0.9 to 2.5 nm, the biexciton lifetime (τ₂) of Ag₂Se QDs increases from 35 to 736 ps, which is approximately 10 times longer than that of comparable-sized CdSe and PbSe QDs. A qualitative analysis based on observables indicates that the slow Auger rate is primarily attributed to the low density of the final states. The biexciton lifetime and triexciton lifetime (τ₃) of Ag₂Se QDs follow R³ and R^2.6 dependence, respectively. Moreover, the ratio of τ₂/τ₃ is ∼2.3-3.2, which is markedly lower than the value expected from statistical scaling (4.5). These findings suggest that environmentally friendly Ag₂Se QDs can serve as excellent candidates for low-threshold lasers and third-generation photovoltaics utilizing carrier multiplication.

Keywords: Auger recombination; colloidal quantum dot; density of states; near-infrared; state degeneracy.