Silylene-Copper-Amide Emitters: From Thermally Activated Delayed Fluorescence to Dual Emission

Herein, we report the inaugural instance of N-heterocyclic silylene (NHSi)-coordinated copper amide emitters (2-5). These complexes exhibit thermally activated delayed fluorescence (TADF) and singlet-triplet dual emission in anaerobic conditions. The NHSi-Cu-diphenylamide (2) complex demonstrates TADF with a very small ΔE_ST gap (0.01 eV), an absolute quantum yield of 11 %, a radiative rate of 2.55×10⁵ s^-1, and a short τ_TADF of 0.45 μs in the solid state. The dual emissive complexes (3-5) achieve an absolute quantum yield of up to 20 % in the solid state with a k_ISC rate of 1.82×10⁸ s^-1 and exhibit room temperature phosphorescence (RTP) with lifetimes up to 9 ms. The gradual decrease in the intensity of the triplet state of complex 3 under controlled oxygen exposure demonstrates its potential for future oxygen-sensing applications. Complexes 2 and 3 have been further utilized to fabricate converted LEDs, paving the way for future OLED production using newly synthesized NHSi-Cu-amides.