Fig. 2. Mechanism for sensitization-initiated electron transfer (SenI-ET) with the fac-[Ir(ppy)3]/2,7-di-tert-butylpyrene (tBuPy)/N,N-dimethylaniline (DMA) combination. Colored circles mark the four key elementary reaction steps of (1) triplet–triplet energy transfer (TTET, Section 2.1), (2) triplet–triplet annihilation upconversion (TTA-UC, Section 2.2), (3) pyrenyl radical anion formation (Section 2.3), and (4) substrate activation (Section 2.4). Grey circles mark possible side reactions.
