Unprecedented stacking-dependent piezoluminescence enhancement in atomically precise superatomic gold nanoclusters.

Deciphering the structure-property relationship between cluster stacking and high-efficiency luminescence of metal nanoclusters is crucial for designing and synthesizing high-performance light-emitting materials and devices. Here, we successfully synthesized two polymorphic gold nanoclusters (Au-C and Au-P) and investigated their stacking-dependent piezoluminescence based on hydrostatic pressure. Under compression, Au-C exhibits notable piezoluminescence enhancement. However, Au-P presents monotonic piezoluminescence quenching. High-pressure structural characterizations confirm the existence of stacking-dependent anisotropic compression in Au-C and Au-P. Under high pressure, the columnar-stacked Au-C shrinks faster along the axis, increasing the aspect ratio (AR) of the fusiform Au core. However, the layered Au-P is compressed faster along the axis, reducing the AR and leading to a flatter Au core. High-pressure femtosecond transient absorption, time-resolved photoluminescence, and Raman spectra collaboratively confirm that differentiated anisotropic compression notably suppresses nonradiative loss caused by low-frequency vibrations of the Au core, which is responsible for the piezoluminescence enhancement in Au-C.