Systematic Computational Design and Optimization of Light Absorbing Dyes

Abstract

We present a workflow to aid the discovery of new dyes for the role of a photosensitive unit in the dye-sensitized photo-electrochemical cells (DS-PECs). New structures are generated in a fully automated way using the Compound Attachment Tool (CAT) introduced in this work. These structures are characterized with efficient approximate density functional theory (DFT) methods, and molecules with favorable optical properties are suggested for possible further use in DS-PECs. As around 2500 structures are generated in this work, and as we aim for still larger volumes of compounds to screen in subsequent applications, we have assessed the reliability of low-cost screening methods and show that simplified time-dependent density functional theory (sTDDFT) provides a satisfying accuracy/cost ratio. From the dyes considered, we propose a set that can be suitable for panchromatic sensitization of the photoelectrode in DS-PECs to further increase DS-PEC efficiency.

Automated assessment of redox potentials for dyes in dye-sensitized photoelectrochemical cells

“…A great advantage is the modularity of the DS-PEC system, thus one may study its molecular components separately and define suitable components before constructing an overall model. Studies on molecular components therefore encompass dyes with favourable light absorption properties, 17 anchoring groups between the dye and the semiconductor for ultrafast electron injection 18 and the WOC-dye complex for driving the water splitting process. 19,20 Analysis and screening of the individual components will help to define optimal DS-PECs and to improve upon the hydrogen production efficiency.…”

Two‐Channel Model for Electron Transfer in a Dye‐Catalyst‐Dye Supramolecular Complex for Photocatalytic Water Splitting

“…The family of NDI chromophores has shown excellent thermal, chemical and photochemical stability and good photoelectronic properties in various fields, which makes them promising candidates for organic electronics applications, photovoltaic devices, and artificial photosystems [14] . Moreover, the optical properties of the NDI chromophores can be easily tuned over a wide light‐spectrum by adding one or more substituents to the core molecule [15] . Specifically, the NDI dye with diethoxy functional groups considered in this work has been demonstrated to be able to perform fast electron injection in the TiO 2 semiconductor conduction band on a time scale of picoseconds upon photooxidation [5,13a] .…”

“…[14] Moreover, the optical properties of the NDI chromophores can be easily tuned over a wide light‐spectrum by adding one or more substituents to the core molecule. [15] Specifically, the NDI dye with diethoxy functional groups considered in this work has been demonstrated to be able to perform fast electron injection in the TiO 2 semiconductor conduction band on a time scale of picoseconds upon photooxidation. [ 5 , 13a ] The stability of the mononuclear WOC [(cy)Ru II bpy(H 2 O)] 2+ has been investigated using online electrochemical mass spectrometry (OLEMS) and in situ surface enhanced Raman spectroscopy (SERS) in our previous work.…”

Efficient workflow for the investigation of the catalytic cycle of water oxidation catalysts: Combining GFN‐xTB and density functional theory

“…Electronic configurations change through the catalytic cycle, which affects the nature of the HOMO and its energy. Computational investigations with for example, estimation of redox potentials, orbital energies, and excitation energies can help in finding suitable combinations of dye and WOC candidates 9 . Dynamics and solvent effects should also be taken into account to simulate both water oxidation as well as the initial photooxidation of a dye‐WOC complex to obtain reliable insight in electron and hole transfer processes 10 .…”

“…Computational investigations with for example, estimation of redox potentials, orbital energies, and excitation energies can help in finding suitable combinations of dye and WOC candidates. 9 Dynamics and solvent effects should also be taken into account to simulate both water oxidation as well as the initial photooxidation of a dye‐WOC complex to obtain reliable insight in electron and hole transfer processes. 10 DFT‐based ab initio molecular dynamics coupled with enhanced sampling techniques have been employed quite successfully in determining reaction barriers for water oxidation processes with oxidized WOCs, 11 , 12 , 13 , 14 redox mediators 15 , 16 or photo‐oxidized dyes.…”