Harnessing White‐Light Luminescence via Tunable Singlet‐and Triplet‐Derived Emissions Based on Gold(III) Complexes *

Abstract

White light emitting gold(III) complexes were synthesized by tuning the percentage of metal dπ contribution in the charge transfer. This was achieved through specific tailoring of the ligand scaffold, which led to increase in the HOMO π-energy properties, resulting in a decrease of efficiency on the intersystem crossing (ISC). As a consequence, monomolecular based singlet- and triplet-derived emission covering the entire visible spectrum with quantum yield up to 28 % and CIE-1931 chromaticity coordinates of (0.29, 0.33) to (0.32, 0.40) could be obtained. Furthermore, two complexes displayed excitation-dependent emission property due to hyper-ISC allowing the regulation of the ratio between fluorescence versus phosphorescence intensity and accomplish precise tuning of white light emission.

Thermally Robust and Tuneable Phosphorescent Gold(III) Complexes Bearing (N^N)‐Type Bidentate Ligands as Ancillary Chelates

“…No oxidation peaks were observed (see Figures S7–S14). The reduction peaks are similar to previously reported mono‐cyclometalated complexes and are ascribed to be a predominately cyclometalating ligand‐centred electrochemical event . Electrochemical data for all final complexes 1 a – 6 b are represented in Table .…”

Single‐Molecular White‐Light Emitters and Their Potential WOLED Applications

“…Later, Venkatesan reported a series of gold(III) complexes ( 106 – 109 , Scheme ) which exhibit the HE singlet emission and the LE triplet emission. As a result, these complexes show the white‐light emission with the blue emission band from 400 to 500 nm and a broad emission from 500 to 650 nm (Figure b) . Besides, the copper cluster [DBFDP] 2 Cu 4 I 4 ( 110 ) shows a broad emission with three emission bands at around 450, 530, and 610 nm (Figure c) due to the mixture of 3 LE/ 3 MLCT, 3 XLCT (halogen‐ligand CT), and cluster centered ( 3 CC) transitions, demonstrating that the copper‐based cluster has a great potential to achieve the white‐light emission …”

“…For the white photoluminescence (PL) emitted from a single molecule, panchromatic or dual emissions are commonly used, which are assigned to both the blue emission in the HE region and a broad emission in the LE region. The blue emission is originated from the excited state of π–π* transition and/or singlet metal‐to‐ligand charge‐transfer ( 1 MLCT), while the low energetic emission could be generated from π···π interaction (dimer or excimer), partially excited energy‐transfer, intramolecular charge transfer (ICT, exciplex), metal‐to‐metal interaction (especially for the platinum(II) (Pt(II)) complexes), excited‐state proton transfer (ESPT), triplet excited states ( 3 MLCT and/or triplet ligand‐to‐ligand charge‐transfer ( 3 LLCT)). The complementary broad emission would occur in both solution and solid film.…”

“…Copyright 2017, American Chemical Society of Chemistry. b,d,e) Reproduced with permission . Copyright 2017 and 2018, John Wiley and Sons.…”

Thermally Stable Donor–Acceptor Type (Alkynyl)Gold(III) TADF Emitters Achieved EQEs and Luminance of up to 23.4% and 70 300 cd m−2 in Vacuum‐Deposited OLEDs

“…[3][4][5][6][7] Due to the electrophilic nature/relatively high reduction potential of Au(III) ion, the luminescent excited states of Au(III) complexes are usually ligand centered with little metal character, resulting in long triplet emission lifetimes, [8][9][10][11][12][13][14][15] thereby posing significant challenges to achieve high performance OLEDs with low efficiency roll-off at high luminance and driving voltage. The first example of gold OLED was reported by Ma and Che in 1999 [1,2] with inferior performance, and device performance has been improved in recent years exploiting luminescent cyclometalated Au(III) complexes.…”