Photostability of thermally-hydrosilylated silicon quantum dots

The photostability of luminescent silicon quantum dots is critical for optoelectronic and photovoltaic applications. While nanocrystals synthesized in a nonthermal plasma and thermally-hydrosilylated with dodecyl groups exhibit quantum yields exceeding 60%, their optical properties degrade with UV exposure. A 20% (absolute) reduction in quantum yield was observed within 4 h of UV irradiation. The origin of instability was identified to stem from unpaired electrons generated at the nanocrystal surface as a result of the breaking of silicon hydride bonds. Recovery of the nanocrystals' quantum yield can be achieved by passivating the dangling bonds generated during photobleaching. Moreover, no degradation in optical properties was observed with further UV irradiation, indicating that photostable silicon nanocrystals were synthesized.