Photoluminescence from colloidal silicon nanoparticles: significant effect of surface

Abstract

AbstractSilicon nanoparticles (NPs) have long been regarded as a promising alternative for commercial organic dyes and typical quantum dots (e.g. CdSe) for applications in light emitting, bio-imaging, sensing, etc. The photoluminescence (PL) of Si NPs, since the first observation in the early 1990s, now has shown wide tunability in the PL wavelength ranging from UV to near IR and lifetime from less than nanoseconds to hundreds of microseconds. Meanwhile, the synthetic advances and methods of size separation and surface modification have improved the quantum yield of Si NPs up to 90% and the PL bandwidth down to ~30 nm FWHM. On the other hand, despite more than 20 years of research, it remains controversial in terms of the exact origin and mechanism of the PL from Si NPs. In this review, we intend to relate the structure of Si NPs with their optical properties in the hope of revealing some general, underlying laws of the size/surface-property relationships based on the reported research. Especially, we highlight the latest research progress on the complex influences of surface chemistry, such as the surface nitrogen capping and surface oxidation, which can dramatically alter and enhance the PL properties of Si NPs.