Singlet Fission and Electron Injection from the Triplet Excited State in Diphenylisobenzofuran-Semiconductor Assemblies: Effects of Solvent Polarity and Driving Force
Journal article, 2020

Singlet fission has emerged as a promising way to overcome the Shockley-Queisser limit in solar energy conversion devices, and a few studies have claimed proof-of-principle results using dye-sensitized photoelectrodes. However, a detailed understanding of what factors govern the fate of the excited state on mesoporous surfaces is still lacking. Here, we have studied how the excitation progresses into singlet fission, electron injection, or formation of molecular charge separated states in diphenylisobenzofuran derivatives with flexible carbon linkers attached to nanocrystalline mesoporous ZrO2, TiO2, and SnO2 thin films. We show that singlet fission occurs for the molecule attached to ZrO2 films when the assembly is immersed in nonpolar solvents, and that singlet fission is hampered by the formation of a molecular charge separated state in more polar solvents. On TiO2 surfaces, direct electron injection from the singlet excited state outcompetes the singlet fission. Instead, triplet formation occurs via charge recombination from the conduction band of TiO2 in nonpolar solvents. When the molecule is attached to SnO2 films, singlet fission partly outcompetes electron injection from the singlet excited state and the two processes occur in parallel. Subsequent to singlet fission on SnO2, triplet injection into the conduction band of SnO2 is observed. The results presented here provide a detailed picture of the singlet fission dynamics in molecules attached to mesoporous semiconductor surfaces, demonstrating that both the semiconductor substrate as well as the environment around the molecules have a large impact, which can be useful in the design of future devices.

Author

Elin Sundin

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry, Physical Chemistry

Rasmus Ringström

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry, Physical Chemistry

Fredrik Johansson

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry, Physical Chemistry

Betül Kücüköz

Chalmers, Physics, Nano and Biophysics

Andreas Ekebergh

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Victor Gray

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Bo Albinsson

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Jerker Mårtensson

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Maria Abrahamsson

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Journal of Physical Chemistry C

1932-7447 (ISSN) 1932-7455 (eISSN)

Vol. 124 38 Josef Michl Festschrift 20794-20805

Areas of Advance

Nanoscience and Nanotechnology (SO 2010-2017, EI 2018-)

Energy

Materials Science

Subject Categories

Physical Chemistry

Theoretical Chemistry

DOI

10.1021/acs.jpcc.0c06626

More information

Latest update

12/3/2020