Quenching and recovery of photoluminescence intensity of silicon nanoparticles embedded in optically transparent polymers

The quenching of photoluminescence (PL) intensity due to exposure to laser radiation (0.25 W cm(-2)) and complete recovery is observed for porous silicon nanoparticles (PSNs) embedded in an optically transparent ultraviolet cured polymer. Under identical laser exposures, the PL intensity of PSNs embedded in transparent polymer and as-prepared porous silicon quenches rapidly for the initial 15 min, followed by a slower rate of decay. On the other hand, a complete lack of quenching is seen in PSNs embedded in polymethylmethacrylate (PMMA). An empirical relation using two time constants has modelled the decay. The time constants characterizing the initial and later stages of quenching are larger for the PSNs embedded in the optical polymer by a factor of four to ten. A method for monitoring the recovery process avoiding quenching during measurement has been identified. The recovery process is slow with a time constant much larger than that observed during quenching.