Modulating Precursor Reactivity for Precise Control of NIR-II Optical Properties in Ag2Te Quantum Dot Synthesis

Abstract

Silver telluride (Ag2Te) quantum dots (QDs) are promising infrared semiconductors due to their environmentally friendly composition and tunable optical properties in the near-infrared II region. However, conventional Te precursors, such as Te dissolved in trioctylphosphine (TOP), often result in inconsistent growth dynamics, leading to poor size uniformity and reproducibility due to their high reactivity. In this study, we present tris(dimethylamino)phosphine ((DMA)3P) as a reliable alternative Te precursor for the controlled synthesis of Ag2Te QDs. QDs synthesized with trioctylphosphine telluride (TOP-Te) exhibited rapid monomer depletion, driven by the precursor's fast reactivity, resulting in inconsistent growth dominated by Ostwald ripening and surface dissolution. This instability hindered size uniformity and optical performance. In contrast, QDs synthesized with tris (dimethylamino) phosphine telluride ((DMA)3P-Te) demonstrated slow and controlled Te release, attributed to the stronger P-Te bond and the enhanced electron-donating ability of the dimethylamino groups. This gradual release minimized nucleation events and promoted a growth-dominated reaction pathway, resulting in QDs with uniform size distribution and enhanced optical stability. These findings underscore the importance of Te precursor chemistry in achieving precise control over QD growth and highlight the advantages of (DMA)3P-Te as an alternative to TOP-Te.