Advanced theory of multiple exciton generation effect in quantum dots
Institute of Polymer Chemistry and Physics Academy of Sciences of Uzbekistan, A. Kadiry str. 7B, 100128 Tashkent, Uzbekistan
Received: 8 June 2011
Received in final form: 17 April 2012
Published online: 25 June 2012
The theoretical aspects of the effect of multiple exciton generation (MEG) in quantum dots (QDs) have been analysed in this work. The statistical theory of MEG in QDs based on Fermi’s approach is presented, taking into account the momentum conservation law. According to Fermi this approach should give the ultimate quantum efficiencies of multiple particle generation. The microscopic mechanism of this effect is based on the theory of electronic “shaking”. According to this approach, the wave function of “shaking” electrons can be selected as Plato’s functions with effective charges depending on the number of generated excitons. From the theory it is known increasing the number of excitons leads to enhancement of the Auger recombination of electrons which results in reduced quantum yields of excitons. The deviation of the averaged multiplicity of the MEG effect from the Poisson law of fluctuations has been investigated on the basis of synergetics approaches. In addition the role of interface electronic states of QDs and ligands has been considered by means of quantum mechanical approaches. The size optimisation of QDs has been performed to maximise the multiplicity of the MEG effect.
Key words: Topical issue: From photophysics to optoelectronics of zero- and one-dimensional nanomaterials
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2012