Blue Luminescence of Facial Tris(quinolin‐8‐olato)aluminum(III) in Solution, Crystals, and Thin Films

Isolation, mass production, and characterization in solution and in the solid state of the facial stereoisomer of tris(quinolin‐8‐olato)aluminum( III ) (Alq 3 ) is reported. A phase‐ transformation diagram shows how to selectively produce the two blue‐emitting polymorphs of the fac isomer (γ‐ and δ‐Alq 3 ; see Figure) via a solid‐to‐solid reaction, opening the route to the development of blue‐light‐emitting Alq 3 ‐based OLEDs.