Molecular aggregation greatly affects the fluorescence quantum efficiency, transient lifetime, and amplified spontaneous emission (ASE) of bis-styrylbenzene derivatives. We compare the optical properties for various morphologies (solution, film, doped film, and single crystalline state) (see figure) and demonstrate that ambi-polar operation of a 1,4-bis(4-methylstyryl) benzene layer in field-effect transistors leads to intense blue electroluminescence with a rather sharp emission width.