{Charging quenches multiple exciton generation in semiconductor nanocrystals: first-principles calculations on small PbSe clusters}

Citation:

Isborn, C. M., & Prezhdo, O. V. (2009). {Charging quenches multiple exciton generation in semiconductor nanocrystals: first-principles calculations on small PbSe clusters}. Journal of Physical Chemistry C, 113, 12617–12621.

Abstract:

We demonstrate using symmetry adapted cluster theory with configuration$\backslash$ninteraction \{(SAC-CI)\} that charging of small \{PbSe\} nanocrystals$\backslash$n\{(NCs)\} greatly modifies their electronic states and optical excitations.$\backslash$nConduction and valence band transitions that are not available in$\backslash$nneutral \{NCs\} dominate low energy electronic excitations and show$\backslash$nweak optical activity. At higher energies these transitions mix with$\backslash$nboth single excitons \{(SEs)\} and multiple excitons \{(MEs)\} associated$\backslash$nwith transitions across the band-gap. As a result, both \{SEs\} and$\backslash$n\{MEs\} are significantly blue-shifted, and \{ME\} generation is drastically$\backslash$nhampered. The overall contribution of \{MEs\} to the electronic excitations$\backslash$nof the charged \{NCs\} is small even at very high energies. The calculations$\backslash$nsupport the recent view that the observed strong dependence of the$\backslash$n\{ME\} yields on the experimental conditions is likely due to the effects$\backslash$nof \{NC\} charging.