Domain-Based Charge-Transfer Decomposition and Its Application to Explore the Charge-Transfer Character in Prototypical Dyes

We introduce a new domain-based charge-transfer analysis tool exploiting the locality of pair Coupled Cluster Doubles orbitals. Unique features of the proposed model include the ability to monitor the direction of the charge flow between different parts or moieties of the system and its quantitative evaluation. We assess the predictive power of our new method for selected dye candidates of dye-sensitized solar cells with different doping and structural arrangements and compare our results for excitation and orbital energies to various density functional approximations and the domain-based local pair natural orbital variant of coupled cluster singles doubles. Our work confirms that the dyes with S-doped bridges are the most promising candidates for dye-sensitized solar cells applications, featuring the largest donor → bridge → acceptor directed charge transfer and the most favorable electrodonating and electroaccepting powers.