Research Article

Size-Dependent Non-FRET Photoluminescence Quenching in Nanocomposites Based on Semiconductor Quantum Dots CdSe/ZnS and Functionalized Porphyrin Ligands

Figure 7

Scheme of QD PL quenching model. (a) Scheme of the electron delocalization in the excited CdSe/ZnS QD being attached with mesopyridyl-substituted porphyrin molecule. Upon excitation, an electron-hole pair (exciton) is created in the QD CdSe core. The electron is delocalized over the core and the ZnS shell. As a result of the finite ZnS energy barrier , the electron can tunnel to the ZnS surface (and to the environment). Upon interaction with the lone-pair of a pyridyl group of a porphyrin molecule, the electron becomes partly localized in the vicinity of the attachment site. (b) Calculated radial part of the probability density function for 1 s electron in a multi shell spherical potential for five QDs of different sizes: 1—  nm, ; 2—  nm, ; 3—  nm, ; 4—  nm, ; 5—  nm, (calculation details are presented in the text).