Spectral single and stable green exciplex emission was demonstrated from organic light-emitting diodes (OLEDs) with 4,4′,4″-tris[3-methylphenyl(phenyl)amino] triphenylamine and 4,7-diphenyl-1,10-phenanthroline that function as electron donor (D) and acceptor (A), respectively. As 8-hydroxyquinoline aluminum (Alq3) was attached to the acceptor layer, electroluminescent (EL) properties of the two exciplex-type OLEDs with D/A-bilayer and D:A mixture layer configurations were markedly improved, i.e., a peak current efficiency of 7.6 cd/A at 2.38 mA/cm2 in three-layer device and a maximum luminance of 6620 cd/m2 at 8.7 V in blend layer device were obtained, respectively, without changing the peak position (535 nm) and the shape of EL spectrum. Discussion is given on the harvest of the pure green exciplex emission and enhancement of luminance which is obtained by inserting Alq3 layer. [ABSTRACT FROM AUTHOR]