Efficient triplet-triplet annihilation upconversion in binary crystalline solids fabricated: Via solution casting and operated in air

Abstract

Binary crystalline solids consisting of a sensitizer (Pt-octaethylporphyrin) and an emitter (9,10-diphenylanthracene (DPA) or its alkyl-strapped derivative (C7-sDPA)) were fabricated by solution casting under rapid drying conditions and found to show efficient triplet-triplet annihilation upconversion by the suppression of component segregation. Microspectroscopic studies of individual crystalline particles of the binary solids revealed threshold intensities as low as 5 mW cm-2, close to solar levels, and UC quantum yields of 20% were possible when using C7-sDPA as an emitter, even in air.