Forster Resonance Energy Transfer Sensitized Singlet Fission in BODIPY-Pentacene Dimer Conjugates

In the present work, the energy donor 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) is used for the first time in combination with a pentacene dimer (Pnc(2)) to provide the conjugate BODIPYPnc(2) that features absorption throughout a large part of the solar spectrum. Upon photoexcitation, the singlet excited state energy of BODIPY is transferred to the pentacene dimer via intramolecular Forster resonance energy transfer (FRET). Subsequently, the pentacene dimer undergoes intramolecular singlet fission. In this process, a singlet correlated triplet pair is generated from the first singlet excited state via coupling to an intermediate state. The results show that solvent polarity has an influence on the system, with the largest FRET rate (i.e., 7.46 x 10(11) s(-1)) being obtained in the most polar solvent (namely, benzonitrile) along with the largest triplet quantum yield (i.e., 207 & PLUSMN; 20%).

Automated summary

In this study, the energy donor BODIPY is combined with pentacene dimer to form a conjugate BODIPYPnc(2) that can absorb a broad range of solar spectrum. Upon photoexcitation, the singlet excited state energy of BODIPY is transferred to the pentacene dimer through FRET, and then the pentacene dimer undergoes singlet fission. The results indicate that solvent polarity affects the system, with the highest FRET rate and triplet quantum yield obtained in the most polar solvent benzonitrile.