Photoluminescence from Silicon Nanocrystals in Encapsulating Materials

Naturally oxidized freestanding silicon nanocrystals (Si NCs) are incorporated in commonly used encapsulating materials to explore the photoluminescent application of Si NCs in device structures such as solid-state lighting light-emitting diodes (LEDs) and solar cells. The quantum yield of Si NCs before the incorporation has reached about 45% at the excitation wavelength of 370 nm without any special surface modification. It is found that medium loadings, e.g., 5 wt% of Si NCs in encapsulating materials help to obtain high external quantum efficiency (EQE) of the mixtures of Si NCs and encapsulating materials. The curing of encapsulating materials significantly reduces EQE. Among all the encapsulating materials investigated in this work, silicone-OE6551 enables the highest EQE (21% at excitation wavelength lambda(ex) = 370 nm) after curing. Based on current findings, we have discussed the continuous efforts to advance the photoluminescent application of Si NCs.