Organic Light Emitting Diodes (OLED) open the door for a new generation of high quality flat panel displays and energy efficient solid state lighting. The use of organic materials allows for low temperature vacuum sublimation or printing techniques to cover large areas of flexible plastic substrates with very thin layers of semiconducting and electroluminescent organic molecules. In order to design appropriate molecules for charge transport materials as well as emitters on a rational basis, a molecular picture of charge migration as well as radiative decay mechanisms is necessary.<br/>As an example for the simulation of charge carrier mobilities we will discuss the transport properties of a BASF host material for deep blue phosphorescent OLEDs. The study includes realistic disordered morphologies, polarized site energies to describe diagonal disorder, quantum chemically calculated transfer integrals for the off-diagonal disorder, inner sphere reorganization energies and an approximate scheme for outer sphere reorganization energies. Intermolecular transfer rates were calculated via Marcus theory and mobilities were determined via kinetic Monte Carlo simulations. An analysis of charge transport in molecular terms will be given.<br/>Phosphorescent emitters are key ingredients to enable efficient OLED-emission. Short emissive lifetimes in combination with high quantum yields are among the targets of rational design. Details of spin-orbit coupling mechanisms in organometallic emitters will be analyzed by relativistic quantum chemical techniques. The use of triplet excitons via thermally excited singlet states will be discussed as well.

Quantum chemical view on OLEDs: designing charge transport materials and phosphorescent emitters

249th National Meeting (2015)

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