Highly emissive gold(I) and gold(III) complexes for potential light-emitting applications: synthesis, excited state properties and devices
Photoactive small molecules (PASMs) are indispensable in today’s technologies as they are widely applied in optoelectronics devices, photocatalysis and photodynamic therapy. Compared to the extensively investigated PASMs containing platinum and iridium as metal centers, research on PASMs with gold metal centers is underexplored and therefore their applications are currently limited. The main goal of this thesis is to develop novel gold based PASMs with interesting light emission properties. Detailed experimental work supported by computational calculations as well as fabrication of devices have been used to explore their light emission properties and their potential applications in optoelectronic devices for lighting technologies.
In Chapter 1, we present the recent conceptual advances in the preparation and excited state properties of neutral luminescent (C^N) and (C^C*) monocyclometalated complexes and correlate experimental findings with computational calculations in order to identify current challenges on this interesting topic.
In Chapter 2, we report the synthesis, characterization and the photophysical properties of highly stable Au(III) complexes having a bis-bidentate ligand framework. Key for the increased stability was the introduction of a dianionic (N^N) type ligand. A combination of various cyclometalating ligands with extended π-system were strategically chosen to tune the triplet excited state systematically to achieve room-temperature emission from the gold(III) complexes.
A unique and unexplored class of highly stable monocyclometalated Au(III) complexes are reported in Chapter 3. Key feature of these complexes is the introduction of a strong σ-donating N-heterocyclic carbene (NHC) cyclometalating ligand framework, leading to more efficient room temperature emitters, which can be applied in OLED devices.
In Chapter 4 we present monocyclometalated (C^N) gold(III) metallacycles bearing a (R^R) type diacetylide chelate. The increased rigidity resulted in long-lived excited states in solution, which favored the energy transfer with triplet oxygen (3O2) to produce singlet oxygen (1O2).
In order to achieve deep-blue emission, a new class of carbene-gold(I)-amides is presented in Chapter 5. Ultimately, the remarkable photophysical properties of these emitters led to the fabrication of a deep-blue emitting OLED device.