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Super‐Efficient Exciton Funneling in Layer‐by‐Layer Semiconductor Nanocrystal Structures
Author(s) -
Klar T. A.,
Franzl T.,
Rogach A. L.,
Feldmann J.
Publication year - 2005
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.200401675
Subject(s) - nanocrystal , materials science , exciton , luminescence , semiconductor , layer (electronics) , funnel , excitation , nanotechnology , optoelectronics , band gap , condensed matter physics , physics , chemistry , organic chemistry , quantum mechanics
In semiconductor nanocrystals the electronic energy gap is determined not only by the material but also by the size of the nanocrystals. This allows the construction of an energy‐gap gradient normal to multiple layers of nanocrystals where the diameters of the nanocrystals are monotonically increasing or decreasing in subsequent layers. In such devices we observe a highly efficient funneling of excitation energy from layers comprising smaller nanocrystals towards the layer with the largest nanocrystals in the center of the funnel. Most importantly, not only are excitons in radiative states transferred, but also excitons from trapped states, usually lost for luminescence, can be effectively recycled, hence increasing the overall luminescence yield.