10.1021/acs.jpcc.8b04931.s001 Christopher S. Kerr Christopher S. Kerr Artem Kryukovskiy Artem Kryukovskiy Jennifer I. L. Chen Jennifer I. L. Chen Effects of Surface Passivation on Trap States, Band Bending, and Photoinduced Charge Transfer in P3HT/TiO<sub>2</sub> Hybrid Inverse Opals American Chemical Society 2018 polymer framework TiO 2 nanoparticles photoinduced charge transfer TiCl 4 polaron P 3HT 2 Hybrid Inverse Opals TiO 2 passivation reagent Photoinduced Charge Transfer unpassivated P 3HT 2 metal oxide opal 2018-07-12 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Effects_of_Surface_Passivation_on_Trap_States_Band_Bending_and_Photoinduced_Charge_Transfer_in_P3HT_TiO_sub_2_sub_Hybrid_Inverse_Opals/6847463 We investigate the effect of a common TiO<sub>2</sub> passivation reagent, TiCl<sub>4</sub>, on the photoinduced charge transfer of poly­(3-hexylthiophene) (P3HT) to TiO<sub>2</sub> in the inverse opal structure. Treating the inorganic oxide framework with TiCl<sub>4</sub> leads to an increase in the size of the TiO<sub>2</sub> nanoparticles, a thickening of the inverse opal framework, and a decrease in the trap-state photoluminescence. These changes lead to different energy alignments at the interface. In comparison to the unpassivated P3HT/TiO<sub>2</sub> inverse opal, we measured a larger polaron yield, by as high as ninefold, and significantly shorter and more uniformly distributed polaron lifetimes in TiCl<sub>4</sub>-treated samples. We show that downward band bending in the polymer can be circumvented by tuning the trap states on the metal oxide using TiCl<sub>4</sub>, thereby eliminating the energetic barrier for photoelectron injection from the polymer to the metal oxide. The findings suggest a way to overcome a potential factor that has plagued the performance of metal oxide–polymer hybrid photovoltaics.