Requirements for LEP layer to achieve a high-performance OLED:

i) color purity, determined by the polymer bandgap and film morphology,

ii) matching of ionization potentials & electron affinities between LEP and the electrode materials,

iii) high photo-luminescence quantum efficiency,

iv) chemical & thermal stability,

v) high processability (solubility, solution viscosity, solvent-substrate compatibility).

Light emitting mechanism from an OLED device

Absorption and emission spectra in solid state

m= 7 solid line

m= 12 dashed line

Konstandakopoulou, F. D.; Kallitsis, J. K. J Polym Sci Part A: Polym Chem 1999, 37, 3826.

E.K. Pefkianakis, N.P. Tzanetos and J.K. Kallitsis Chemistry of Materials 2008, 20, 6254–6262

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