Dramatic enhancement of photoluminescence quantum yields for surface-engineered Si nanocrystals within the solar spectrum

Substantial improvements of the absolute photoluminescence quantum yield (QY) for surfactant-free silicon nanocrystals (Si-ncs) by atmospheric pressure microplasma 3-dimensional surface engineering are reported. The effect of surface characteristics on carrier multiplication mechanisms is explored using transient induced absorption and photoluminescence QY. Surface engineering of Si-ncs is demonstrated to lead to more than 120 times increase in the absolute QY (from 0.1% up to 12%) within an important spectral range of the solar emission (2.3-3 eV). The Si-ncs QY is shown to be stable when Si-ncs are stored in ethanol at ambient conditions for three months. Dramatic improvements in the absolute photoluminescence quantum yield (QY) and stability of surfactant-free 3D surface- engineered silicon nanocrystals (Si-ncs) within an important spectral region are demonstrated. The microplasma-induced 3D surface engineering results in more than 120 times enhancement QY for low energy photons (<2.7 eV) and ≈15 times higher for high energy photons (3.5-4.8 eV).