Large scale GW-BSE calculations with N3 scaling: excitonic effects in dye sensitised solar cells

TL;DR

This paper introduces a new computational scheme that significantly reduces the complexity of GW-BSE calculations, enabling accurate modeling of excitonic effects in large dye-sensitized solar cell systems.

Contribution

The authors develop a Wannier function-based method that reduces GW-BSE scaling from O(N^4) to O(N^3), allowing large-scale excitonic calculations in solar cell materials.

Findings

Quantitative analysis of interfacial excited states in dye-sensitized TiO2.

A general rule for evaluating energy levels in organic solar cells.

Demonstration of the method's efficiency in large systems.

Abstract

Excitonic effects due to electron-hole coupling play a fundamental role in renormalising energy levels in dye sensitised and organic solar cells determining the driving force for electron extraction. We show that first-principles calculations based on many-body perturbation theory within the GW-BSE approach provide a quantitative picture of interfacial excited state energetics in organic dye-sensitized TiO2 , delivering a general rule for evaluating relevant energy levels.To perform GW-BSE calculations in such large systems we introduce a new scheme based on maximally localized Wannier functions. With this method the overall scaling of GW-BSE calculations is reduced from O(N4) to O(N3).