Au⋅⋅⋅H−C Interactions Support a Robust Thermally Activated Delayed Fluorescence (TADF) Gold(I) Complex for OLEDs with Little Efficiency Roll‐Off and Good Stability

Abstract

The practical use of luminescent mononuclear gold(I) complexes as optoelectronic materials has been limited by their inferior stability. Herein we demonstrate a strategy to improve the stability of gold(I) complexes which display thermally activated delayed fluorescence (TADF). A highly rigid and groove‐like σ‐donating aryl ligand has been used to form dual Au⋅⋅⋅H−C hydrogen bonds. The secondary metal‐ligand interactions have been authenticated by single‐crystal structure, NMR spectroscopy and theoretical simulations. The TADF AuI complex exhibits appealing emission properties (photoluminescence quantum yield=76 %; delayed fluorescence lifetime=1.2 μs) and much improved thermal and photo‐stability. Vacuum‐deposited organic light‐emitting diodes (OLEDs) show promising electroluminescence with a maximum external quantum efficiency (EQE) over 23 % and negligible efficiency roll‐off even at 10 000 cd m−2. An estimated LT50 longer than 77 000 h with initial luminance of 100 cd m−2 reveals good operational stability. This work suggests a way for design of stable luminescent gold(I) complexes.

Highly efficient and stable thermally activated delayed fluorescent palladium(II) complexes for organic light-emitting diodes

“…2 attractive van der Waals interactions are authenticated by the independent gradient model based on Hirshfeld partition (IGMH) analysis of Pd1 based on its optimized structure (41,42). The secondary interactions are surmised to stabilize the metal-amide ligation in Pd1 and Pd2, accounting for their excellent thermal stability (vide infra) (37,38). Therefore, the present work suggests a strategy for robust planar d 8 metal complexes that does not require cumbersome syntheses.…”

“…Moreover, as illustrated in Fig. 1C, intramolecular noncovalent interactions have been integrated into the structural design, which can improve the stability of luminescent transition metal complexes (37,38). Two orange and red TADF Pd(II) complexes (λ max = 598 to 637 nm in doped films) have been synthesized (Fig.…”