Development and study of hybrid organic-colloidal quantum dot systems

We show that in the presence of fullerene complexes the optical properties of PbS QDs are significantly modified. The absorption of the PbS QDs is observed to shift to a higher energy when fullerene complexes are introduced. Upon direct excitation of the PbS below the fullerene absorption a corresponding blue shift in PL spectra of the PbS QDs is observed. The strength of this blue-shift can be related to the fullerene concentration in most cases and is accompanied by a broadening of the emission spectrum. When exciting the samples at high energy 3.4 eV (363 nm) the strength of these effects is increased with a maximum blue-shift in the PL spectrum of 261 meV and 167 meV occurring for the C60 and PCBM doped samples respectively. The origin of the observed behavior cannot be confirmed at this time and is the focus of ongoing studies. However, we briefly discuss the results obtained in relation to the strong electron accepting nature of the fullerene complexes used.