High-Q Microcavity Enhanced Optical Properties of CuInS2/ZnS Colloidal Quantum Dots toward Non-Photodegradation

We report on a temporal evolution of photoluminescence (PL) spectroscopy of CuInS2/ZnS colloidal quantum dots (QDs) by drop-casting on SiO2/Si substrates and high quality factor microdisks (MDs) under different atmospheric conditions. Fast PL decay, peak blue shift, and line width broadening due to photooxidation have been observed at low excitation power. With further increasing of the excitation power, the PL peak position shows a red shift and the line width becomes narrow, which is ascribed to the enhanced Forster resonant energy transfer between different QDs by photoinduced agglomeration. The oxygen plays an important role in optically induced PL decay, which is verified by a reduced photobleaching effect under vacuum. When the QDs are drop-casted on MDs, photooxidation and photobleaching are accelerated because the excitation efficiency is greatly enhanced with coupling the pumping laser with the cavity modes. However, when the emitted photons couple with cavity modes, a PL enhancement by more than...