The Efficiency of Energy Transfer from Quantum Dots to Photosynthetic Reaction Centers of Rhodobacter sphaeroides in the Temperature Range of 100–310 K

The temperature dependence of the efficiency of energy transfer from polymer coated CdSe/CdS/ZnS quantum dots bearing terminal carboxyl groups to the reaction centers of purple bacteria Rb. sphaeroides was investigated experimentally. It was established that this efficiency remained almost constant with the change of temperature from 100 to approximately 230 K, but decreased 2–3 times when temperature rose to 310 K. A possible mechanism of such a temperature dependence based on the views on the activation caused by the intensification of the molecular motion is proposed. In the framework of these views, the analysis of the temperature dependence of the parameters that influence the efficiency of energy transfer, according to Förster's theory, was performed. It was shown that the main contribution to the observed experimental dependence was made by the change in the fluorescence quantum yield of quantum dots, and an additional contribution could be made by diffusion processes and effects of structural changes.