Temperature Dependence of Blue Phosphorescent Cyclometalated Ir(III) Complexes

This chapter focuses on Ir(III) complexes with emission energies ranging from the near-UV to green in order to develop a better understanding of the processes that limit the luminescent efficiency from this class of materials. Key information about the photophysical properties of phosphorescent transition metal complexes can be obtained by studying the temperature dependence of emission from these materials. The temperature dependence of luminescent cyclometalated Pd(II), Rh(III), Pt(II), and Pt(IV) complexes has also been investigated, and these compounds show behavior similar to that of the Ru(II) and Os(II) complexes. The authors have measured the activation energies and kinetic parameters for deactivation of the excited state. Their analysis indicates that thermal population to a MC state is the most likely deactivation processes for high-energy cyclometalated Ir(III) complexes.