An exciplex-type thermally activated delayed fluorescence material with wide up-conversion fluorescence excitation window

Abstract

Exciplexes play an important role in the field of light-emitting materials due to the effective enhancement on fluorescence efficiency through thermally activated delayed fluorescence (TADF) mechanism. This mechanism is also expected to contribute to nonlinear optical applications. Here, we report an exciplex-type TADF material with significant two-photon excited fluorescence (TPEF) properties. It consists of Di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane (TAPC) as the donor and 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) as the acceptor. The TAPC:TPBi film emits blue fluorescence (peaked at ∼470 nm) under near-infrared excitation. A very wide long-wavelength excitation window of at least 200 nm (660 nm–860 nm) was observed. The reported exciplex material may have the potential to play an important role in the field of one- and two-photon excited fluorescence.