Magneto‐Electroluminescence as a Tool to Discern the Origin of Delayed Fluorescence: Reverse Intersystem Crossing or Triplet–Triplet Annihilation?

A novel use of magneto-electroluminescence (MEL) is reported to discern the delayed fluorescence coming from reverse intersystem crossing (RISC) or triplet–triplet annihilation (TTA). The results indicate MEL could be used as a "fingerprinting" technique to exploit the phenomena behind highly efficient fluorescent OLEDs with quantum efficiencies exceeding the 25% theoretical limit.