Using $G_0W_0$ Level Alignment to Identify Catechol's Structure on TiO$_2$(110)

TL;DR

This study uses advanced $G_0W_0$ calculations to interpret spectroscopic data and identify the structure of catechol on TiO$_2$(110), revealing how deprotonation affects photovoltaic efficiency.

Contribution

It compares $G_0W_0$ and HSE DFT methods to interpret spectroscopic signatures, providing insights into catechol's deprotonation and its impact on solar cell interfaces.

Findings

Spectroscopic peaks can identify catechol deprotonation states.

Deprotonation may enhance photovoltaic efficiency.

$G_0W_0$ offers accurate interpretation of experimental spectra.

Abstract

We perform state-of-the-art calculations for a prototypical dye sensitized solar cell: catechol on rutile TiO$_2$(110). Catechol is often used as an anchoring group for larger more complex organic and inorganic dyes on TiO$_2$ and forms a type II heterojunctions on TiO$_2$(110). In particular, we compare quasiparticle (QP) $G_0W_0$ with hybrid exchange correlation functional (HSE) density functional theory (DFT) calculations for the catechol-rutile TiO$_2$(110) interface. In so doing, we provide a theoretical interpretation of ultraviolet photoemission spectroscopy (UPS) and inverse photoemission spectroscopy (IPES) experiments for this prototypical system. Specifically, we demonstrate that the position, presence, and intensity of peaks associated with catechol's HOMO, intermolecular OH$-$O bonds, and interfacial hydrogen bonds to the surface bridging O atoms (O$_{br}$H$-$C and O$_{br}$H$-$O) may be used to fingerprint deprotonation of catechol's OH anchoring groups. Furthermore, our results suggest deprotonation of these groups, while being nearly isoenergetic at high coverages, may significantly increase the photovoltaic efficiency of catechol$-$TiO$_2$(110) interfaces.