Separation of electrical and optical energy gaps: selectively adjusting the electrical and optical properties for a highly efficient blue emitter

The design concept of separation of optical and electrical bandgap for wide bandgap materials is further developed in DCzSiPI. The HOMO/LUMO levels can be tuned by incorporation of PI and DCz substituents. The tetraphenylsilane core avoids the intramolecular charge transfer from DCz to PI (DCz = dimer carbazole, PI = phenanthro[9,10-d]imidazole). The allowed transitions are found to be from HOMO-1 to LUMO providing DCzSiPI with sufficient bandgap.