Energy transfer versus charge separation in type-II hybrid organic-inorganic nanocomposites

A. A. LUTICH; G. JIANG; A. S. SUSHA; A. L. ROGACH; F. D. STEFANI; J. FELDMANN

NANO LETTERS (PRINT)

AMER CHEMICAL SOC

Año: 2009 vol. 9 p. 2636 - 2640

1530-6984

Hybrid organic-inorganic nanomaterials have the potential of providing synergetic properties. Blends of semiconductor nanocrystals and conjugated polymers in particular promise novel optoelectronic properties. Effective design of tailored optoelectronic properties requires a deep understanding of the photophysics of these composite materials, which includes charge separation and Dexter and Fo¨ rster energy transfer. We performed a detailed and quantitative spectroscopic investigation of a type II aligned hybrid system consisting of a blue emitting conducting polymer and CdTe nanocrystals. Although charge separation is expected from the type II alignment, we find a dominant (70% efficiency) energy transfer process. We discuss all possible de-excitation pathways for the excitons in terms of the alignment of energy levels, time scales, and physical geometry of the system. This allows us to conclude that energy transfer occurs via the Fo¨ rster mechanism and provides a clear guideline for the design of novel hybrid materials.