Radiative quantum efficiency of CdSe/ZnS quantum dots suspended in different solvents

The radiative quantum efficiencies η of the CdSe/ZnS core–shell nanoparticles embedded into polymethyl methacrylate (PMMA) and suspended in three different solvents: chloroform (CHCl3), toluene (C6H5CH3) and tetrahydrofuran (C4H8O) were measured using thermal lens (TL) technique. The mode-mismatched pump–probe TL measurements were accomplished in function of the CdSe/ZnS quantum-dot concentration (12–60 mg/ml) at λe = 594 nm (pump) and λp = 632.8 nm (probe). The values obtained for η were higher for CdSe/ZnS nanoparticles suspended in tetrahydrofuran and chloroform, as compared to the values for toluene. Thermal diffusivity (D) and the absolute nonradiative quantum efficiency (φ) were determined.