Near-unity NIR phosphorescent quantum yield from a room-temperature solvated metal nanocluster.

Shi, Wan-Qi; Zeng, Linlin; He, Rui-Lin; Han, Xu-Shuang; Guan, Zong-Jie; Zhou, Meng; Wang, Quan-Ming · Science · 2024

basic_science · Level V

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Abstract

Metal nanoclusters have emerged as promising near-infrared (NIR)-emissive materials, but their room-temperature photoluminescence quantum yield (PLQY), especially in solution, is often low (<10%). We studied the photophysics of Au<sub>22</sub>(<i><sup>t</sup></i>BuPhC≡C)<sub>18</sub> (Au<sub>22</sub>) and its alloy counterpart Au<sub>16</sub>Cu<sub>6</sub>(<i><sup>t</sup></i>BuPhC≡C)<sub>18</sub> (Au<sub>16</sub>Cu<sub>6</sub>) (where <i><sup>t</sup></i>Bu is <i>tert</i>-butyl and Ph is phenyl) and found that copper (Cu) doping suppressed the nonradiative decay (~60-fold less) and promoted intersystem crossing rate (~300-fold higher). The Au<sub>16</sub>Cu<sub>6</sub> nanocluster exhibited >99% PLQY in deaerated solution at room temperature with an emission maximum at 720 nanometers tailing to 950 nanometers and 61% PLQY in the oxygen-saturated solution. The approach to achieve near-unity PLQY could enable the development of highly emissive metal cluster materials.