Light-emitting devices based on organometallic platinum complexes as emitters

This article provides an overview of molecular optoelectronic systems - particularly organic light emitting devices (OLEDs) - that make use of platinum(II) complexes as their emissive components. A comprehensive introduction to the function and classes of OLEDs in general is first provided. The diverse range of parameters that are used to quantify OLED performance can be bewildering, particularly to the chemist, and we set out the relationship between the key parameters, and provide a detailed description of the main physical processes that determine them. We then focus on OLEDs prepared using platinum(II) complexes as dopants. Pertinent recent developments in the chemistry of luminescent Pt(II) complexes containing cyclometallating bidentate and terdentate ligands are presented. Some of these complexes possess outstanding features from the point of view of their electronic structure, photophysical behaviour, processability, and environmental stability. An appreciation of the nature of their molecular excited states has facilitated understanding of the fundamental electronic processes at work within devices, and has led to the fabrication of high-performance OLEDs. In addition to single-colour and white light systems, some of them offer unusual characteristics and applications, such as plant growth OLED (PGOLED) or electro-photoluminescent (EL-PL) switches. Such devices fulfil the requirements to become an important part of 'Green Photonics'.