Secondly, the TTEnT dynamics were studied (Supporting Information). We used PdPc as triplet photosensitizer due to its near unity ISC efficiency, its high molar extinction coefficient of 1.8 × 10 5 M -1 cm -1 at 730 nm, and the minimal spectral overlap between its absorption in the range of 600 to 800 nm and the tetracene fluorescence between 500 to 650 nm (Figure ). Upon photoexcitation of PdPc at 730 nm in toluene, efficient intermolecular TTEnT (inter-TTEnT) from PdPc to the tetracene annihilators is confirmed via Stern-Volmer analyses, and the underlying inter-TTEnT rate constants are determined (kTTEnT; Supporting Information). Considering (T1) energies of 1.13 and 1.21 eV for PdPc and tetracene, respectively, inter-TTEnT is endergonic by +0.08 eV. All kTTEnT values are within the same range of 10 9 M -1 s -1 (Figure and Table ).