The Doping Effects on the NIR Emission Enhancement of Gold Nanoclusters and the Application in Efficient NIR-OLED

Metal nanoclusters (NCs) have emerged as promising near-infrared (NIR) emissive materials. A series of highly red/NIR luminescent Au-Cu nanoclusters have been synthesized, Au_{22- x}Cu_x (^tBuC₆H₄C≡C)₁₈ (x = 0-6) (Au_{22- x}Cu_x). Compared with the parental cluster Au₂₂(^tBuC₆H₄C≡C)₁₈ (Au₂₂), doping effects have been clearly established: the more the amount of doping Cu, the higher photoluminescence quantum yield (PLQY). Remarkable solutions for NIR emission under ambient conditions are found with Au₁₉Cu₃ and Au_17.1Cu_4.9, and the PLQYs at ∼710 nm are ∼55% and ∼72%, respectively. The study on excited state dynamics of these clusters reveals that the more copper atoms doped, the slower nonradiative decay and the faster intersystem crossing rate, the higher PLQY. Surprisingly, an external quantum efficiency (EQE) of ∼15.43% is achieved from a NIR-OLED with Au₁₆Cu₆ as the emitting layer, showing the prospect of metal NCs in potential applications for NIR-OLED.