Impact of Ga–V Codoping on Interfacial Electron Transfer in Dye-Sensitized TiO₂

Abstract

The improvement of charge transfer between an organic molecule and a semiconductor is an important and challenging goal in the fields of photovoltaics and photocatalysis. In this work, we present a time-dependent density functional theory investigation of the impact of Ga-V codoping of TiO2 on the excited-state electron injection from perylene-3-carboxylic acid. The doping is shown to raise the charge-transfer efficiency for the highest possible surface dye uptake by ∼16%. The strength of the effect depends on the dopant-pair-dye separation, dopant concentration, and distribution of Ga, V atoms in TiO2. The doping of the superficial level turns out to be more favorable than those in the bulk. The changes in electron injection dynamics are attributed to the modification of accepting semiconductor levels and hybridization profile between molecular and semiconductor states.

Charge Transfer at the Hybrid Interfaces in the Presence of Water: A Theoretical Study

“…According to the DOS structure (Figure ), the position of the first excited state gets closer to the conduction band edge compared to the clean TiO 2 surface; hence, fewer TiO 2 states are available for injection. The CT decrease is also in line with the previously observed important role of the surface layer in sheltering of injected electrons . Indeed, the hydroxylation of the surface Ti 5c sites restores the bulk coordination number of 6 for these Ti atoms.…”

“…The CT decrease is also in line with the previously observed important role of the surface layer in sheltering of injected electrons. 29 Indeed, the hydroxylation of the surface Ti 5c sites restores the bulk coordination number of 6 for these Ti atoms. At the same time, lower coordination states of Ti are known 30 to be more favorable for the accommodation of reduction electrons.…”

Efficient Computation of Nonadiabatic Coupling Coefficients for Modeling Charge Carrier Recombination in Extended Systems: The Case of Metal–Organic Frameworks

“…The SH simulations in extended solid-state systems, such as MOFs, are typically performed within the classical path approximation (CPA) ,,, to partially reduce the computational cost, which is particularly resource demanding due to the slow decay rates across the band gap, resulting in prolonged simulation times. In extended solid-state systems, in the absence of bond formation or breaking events, the electron dynamics often has a negligible effect − on the ionic dynamics, which justifies the application of CPA, assuming the nuclear motion to be driven by thermal motions and decoupled from the evolution of the electronic subsystem (the back-reaction of nuclei on the motion of electrons is neglected). This approach partially reduces the cost of the SH simulation, but for MOFs, in contrast to molecules and regular solids, it still stays quite resource intensive (Table S1) in view of the large number of atoms and extended unit cell sizes.…”

Computing the Effect of Metal Substitution in Metal–Organic Frameworks on the Recombination Times of Charge Carriers

“…To account for the loss of coherence in the slow relaxation processes, such as electron–hole recombination across the band gap, a decoherence-induced surface hopping (DISH) formulation is proposed by Prezhdo and co-workers . To make such simulations feasible for extended systems like MOFs, it is important to recall that in solid-state systems, excited electron dynamics often produces only a minimal effect on a large number of heavy nuclei, − sometimes even justifying a clamped nuclear approximation. This fact allows us to resort to the classical-path approximation (CPA), , within which the dynamical trajectory is assumed to be dominated by the thermal nuclear motion, while the electron dynamics have a negligible impact on the ionic one.…”