Nearly 100% Internal Quantum Efficiency in an Organic Blue‐Light Electrophosphorescent Device Using a Weak Electron Transporting Material with a Wide Energy Gap

A blue-light electrophosphorescence with an internal quantum efficiency of nearly 100%, much higher than that of a stronger electron transporting (ET) material, was achieved with a weak ET silane. This result contradicts the conventional notion that weak ET materials result in low efficiency.