Bidirectional Photoinduced Energy Transfer in Nanoassemblies of Quantum Dots and Luminescent Metal Complexes

This work describes the synthesis and photophysical characterization of Ir(III) and R(II)) complexes bearing terminal amino groups, which act as anchoring units for the attachment to quantum dots, QDs. The photophysical properties of the metal complexes in combination with different types of QDs, allows directional photoinduced processes in the assemblies. In particular, we show photoinduced energy transfer from the luminescent excited Ir(III) unit to the CdTe nanocrystals, with an efficiency of 40%. The directionality was then inverted by employing an emitting Ru(II) complex as energy acceptor, in combination with photoluminescent CdSe/ZnS quantum dots. The efficiency of the photoinduced energy transfer from the nanocrystals to the Ru(II) center was estimated to be as high as 75%. This work provides model systems for nanoassemblies based on quantum dots and metal complexes for optoelectronic applications, and as active light-harvesting systems.