Ortho-Heterofluorene perylenediimides: synthesis, photophysical, and exciton dynamic properties. Issue 48 (28th November 2016) - Yu, Zhenyi
Abstract : We designed heavy-atom-free perylenediimides (PDIs) to prompt the intersystem crossing (ISC) by introducing electron donating heterofluorene groups at the head positions of electron-deficient PDI core. Abstract : Previous studies suggest the perylenediimide (PDI) triplet excited state (T1 ) have been accessible only through bimolecular sensitization, the internal heavy-atom effect or a sophisticated cascade of nonradiative processes. Here, we designed heavy-atom-free PDIs to prompt the T n ← S1 intersystem crossing (ISC) by introducing electron donating heterofluorene groups at the head positions of the electron-deficient PDI core. We obtained relatively high ISC efficiency up to 92% yield. Furthermore, promptly generated PDI triplets can sensitize the molecular oxygen quantitatively to yield 1 O2, with singlet oxygen generation efficiencies ( Φ Δ ) near to unity. These results further suggest that the ISC process of PDIs can be enhanced through the intramolecular charge transfer (ICT) interaction, providing guidelines for developing triplet-generating PDIs and related rylene diimides for optoelectronic applications.