The effect of electric field on multiple exciton generation in lead chalcogenide nanocrystals

TL;DR

This study investigates how electric fields influence multiple exciton generation in lead chalcogenide nanocrystals, revealing that electric fields affect absorption spectra but have limited impact on MEG probabilities, with Pb4Te4 being the most promising for applications.

Contribution

It provides the first detailed analysis of electric field effects on MEG in lead chalcogenide nanocrystals using advanced many-body simulations.

Findings

Electric fields alter absorption spectra of nanocrystals.

MEG quantum probabilities are minimally affected by electric fields.

Pb4Te4 exhibits the lowest MEG threshold and strongest absorption peak.

Abstract

Unique properties of lead chalcogenides have enabled multiple exciton generation (MEG) in their nanocrystals that can be beneficial in enhancing the efficiency of the 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 (Pb4Te4, Pb4Se4, and Pb4S4). The same electric field, however, has insignificant effects on the MEG quantum probabilities and the thresholds in these nanocrystals. Furthermore, simulations show that Pb4Te4, 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 Pb4Te4 nanocrystal, in general, less than it perturbs MEG characteristics in Pb4Se4 and Pb4S4 nanocrystals. Our results can have a great impact in designing optoelectronic devices whose performance can be significantly influenced by MEG.