Precisely modulated photoluminescence (PL) with external
control
is highly demanded in material and biological sciences. However, it
is challenging to switch the PL on and off in the NIR region with a high modulation contrast. Here, we demonstrate
that reversible on and off switching
of the PL in the NIR region can be achieved in a bicomponent system
comprised of PbS semiconducting nanocrystals (NCs) and diarylethene
(DAE) photoswitches. Photoisomerization of DAE to the ring-closed
form upon UV light irradiation causes substantial quenching of the
NIR PL of PbS NCs due to efficient triplet energy transfer. The NIR
PL fully recovers to an on state upon reversing the
photoisomerization of DAE to the ring-open form with green light irradiation.
Importantly, fully reversible switching occurs without obvious fatigue,
and the high PL on/off ratio (>100)
outperforms all previously reported assemblies of NCs and photoswitches