Color-tuning and stability enhancement of cyclometallated iridium (III) complexes in light-emitting electrochemical cells

Abstract

In this thesis, the design and synthesis of cyclometallated iridium(III) complexes for use in light-emitting electrochemical cells (LEECs) are presented, divided into six chapters. Focus is put on the emission color-tuning of various compounds, covering almost the whole visible spectrum between blue and red including first steps towards white-light emission. Secondly, a new systematic approach for an intrinsic stability enhancement of highly pure Ir(III) complexes is investigated. The work is rounded off by the test results of all compounds for potential commercial application in LEECs. Chapter 1 highlights the historical progress of artificial light from the incandescent light bulb towards ultrathin highly-efficient flexible LEECs and their working principle. Chapter 2 describes the synthesis and photophysical properties of orange-emitting Ir(III) complexes supported by theoretical calculations. Chapter 3 addresses the synthesis and characterization of green-emitting Ir(III) complexes supported by theoretical calculations. Chapter 4 reports the design of linking a blue-emitting naphthyl group to an orange-luminescent Ir(III) complex as well as mixing experiments of a blue and orange compound towards white-light emission. Chapter 5 comprises the effect of multiple intra-cation π-stacking interactions on the long-term stability of Ir(III) complexes in LEECs. Chapter 6 concludes the previous chapters and gives a short outlook for future work in the field of Ir(III) based LEECs.