White Organic Light-Emitting Diode Using the Exciplex Between DNTPD and ET-137

Abstract

Two organic layers of the N,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-biphenyl-4,4′-diamine [DNTPD] and the ET-137 which is a pyran derivative provided from SFC Co. were sequentially deposited between the ITO anode and the LiF/Al cathode for generating blue light-emitting excitons in the electron transport material and yellow light-emitting exciplexes at the interface of two organic layers. In this study, the DNTPD was used as a hole transport layer and the ET-137 as an electron transport and exciton formation layer. The structure of the fabricated devices is very simple compared with those of conventional white organic light-emitting devices (OLEDs) and the emission showed the nearly pure white on the Commission Internationale de I′ Eclarirage (CIE) chart. The device with two organic layers of 500Å-thick DNTPD and 500Å-thick ET-137 showed electroluminescent characteristics of the double peak emission with a peak wavelength of 455 nm from the excitons of ET-137 and a peak wavelength of 561 nm from the exciplexes at the interface of DNTPD and ET-137, the maximum current efficiency of 1.8 cd/A, and the color coordinates of (0.32, 0.37) on the CIE chart.