Discovery of blue singlet exciton fission molecules via a high-throughput virtual screening and experimental approach

Collin F Perkinson; Daniel P Tabor; Markus Einzinger; Dennis Sheberla; Hendrik Utzat; Ting-An Lin; Daniel N Congreve; Moungi G Bawendi; Alán Aspuru-Guzik; Marc A Baldo

doi:10.1063/1.5114789

Discovery of blue singlet exciton fission molecules via a high-throughput virtual screening and experimental approach

J Chem Phys. 2019 Sep 28;151(12):121102. doi: 10.1063/1.5114789.

Affiliations

¹ Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
² Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
³ Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
⁴ Rowland Institute at Harvard University, Cambridge, Massachusetts 02142, USA.

PMID: 31575171
DOI: 10.1063/1.5114789

Abstract

Singlet exciton fission is a mechanism that could potentially enable solar cells to surpass the Shockley-Queisser efficiency limit by converting single high-energy photons into two lower-energy triplet excitons with minimal thermalization loss. The ability to make use of singlet exciton fission to enhance solar cell efficiencies has been limited, however, by the sparsity of singlet fission materials with triplet energies above the bandgaps of common semiconductors such as Si and GaAs. Here, we employ a high-throughput virtual screening procedure to discover new organic singlet exciton fission candidate materials with high-energy (>1.4 eV) triplet excitons. After exploring a search space of 4482 molecules and screening them using time-dependent density functional theory, we identify 88 novel singlet exciton fission candidate materials based on anthracene derivatives. Subsequent purification and characterization of several of these candidates yield two new singlet exciton fission materials: 9,10-dicyanoanthracene (DCA) and 9,10-dichlorooctafluoroanthracene (DCOFA), with triplet energies of 1.54 eV and 1.51 eV, respectively. These materials are readily available and low-cost, making them interesting candidates for exothermic singlet exciton fission sensitization of solar cells. However, formation of triplet excitons in DCA and DCOFA is found to occur via hot singlet exciton fission with excitation energies above ∼3.64 eV, and prominent excimer formation in the solid state will need to be overcome in order to make DCA and DCOFA viable candidates for use in a practical device.