Luminance compensation in top-emitting organic light-emitting diodes with high color purity as quantum dots using horizontal dipole orientation

Abstract

Organic light-emitting diodes (OLEDs) and quantum dots (QDs) are mainstream applications in large-sized displays. Owing to their narrow photoluminescence (PL), QDs offer a wide color gamut. Although OLEDs have a wider PL spectrum bandwidth than that of QDs, a high color purity can be obtained through an optical design of the top-emitting device. However, the luminance improvement from the strong cavity effect in a top-emitting geometry is not significant because of the wide PL spectrum. This insufficient luminance improvement can be compensated by applying organic light-emitting materials with horizontally oriented dipoles. Luminance compensation is color dependent. In a blue light-emitting structure, the luminance improvement by a narrow PL spectrum is more advantageous than by a horizontal dipole orientation. However, in green and red light-emitting structures, even if the full width at half maximum of the PL is about 20-nm-wide, luminance can be compensated using a horizontal dipole orientation while maintaining high color purity. © 2020 Elsevier B.V.