Effects of Electric Fields on Multiple Exciton Generation

Unique properties of lead chalcogenides have enabled multiple exciton generation (MEG) in their nanocrystals that can be beneficial in enhancing the efficiency of third-generation solar cells. Although the intrinsic electric field plays an imperative role in a solar cell, its effect on the multiple exciton generation (MEG) has been overlooked, so far. Using EOM-CCSD as a many-body approach, we show that any electric field can affect the absorptivity spectra of the lead chalcogenide nanocrystals (Pb₄ Te₄ , Pb₄ Se₄ , and Pb₄ S₄ ). The same electric field, however, has insignificant effects on the MEG quantum probabilities and the thresholds in these nanocrystals. Furthermore, simulations show that Pb₄ Te₄ , among the aforementioned nanocrystals, has the lowest MEG threshold and the strongest absorptivity peak that is located in the multi-excitation window, irrespective of the field strength, making it the most suitable candidate for MEG applications. Simulations also demonstrate that an electric field affects the MEG characteristics in the Pb₄ Te₄ nanocrystal, in general, less than it perturbs MEG characteristics in Pb₄ Se₄ and Pb₄ S₄ nanocrystals. Our results can have a great impact in designing optoelectronic devices whose performance can be significantly influenced by MEG.