Large-scale GW-BSE calculations with N~3 scaling: Excitonic effects in dye-sensitized solar cells

摘要

Excitonic effects due to electron-hole coupling play a fundamental role in renormalizing energy levels in dye sensitized 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 TiO_2, delivering a general rule for evaluating relevant energy levels. To perform GW-BSE calculations in such large systems we introduce a scheme based on maximally localized Wannier's functions. With this method the overall scaling of G W-BSE calculations is reduced from 0(N~4) to O(N~3).