Facile fabrication of multi-color electroluminescent devices by tricomponent exciplex regulation

Constructing solid-state electroluminescent devices with different emission colors is of central importance in full-color displays and multi-color illumination. However, the precise selection among various luminescent materials and the design of integrated devices to realize multi-color electroluminescence are usually tough, raising the fabrication costs of organic light-emitting diodes (OLEDs). Here, a facile strategy is proposed to develop multi-color OLEDs simply using only three organic compounds in the device architectures. Three commercially available materials including one electron-accepting (A1) and two electron-donating (D1 and D2) molecules can establish blue and yellow exciplexes. When an ultrathin D2 interlayer with varied thickness is employed at lower surface of D1:A1 layer, a monochromatic OLED with tunable emission wavelength from blue (480 nm) to green (544 nm), then to yellow (572 nm) is achieved. Further, a dichromatic white OLED with a color rendering index (CRI) of 75 is obtained when this interlayer is employed at upper surface. Therefore, four-color emissions with the least component have been ultimately realized by regulating the charge recombination zone. These results illustrate a simple yet promising approach utilizing a tricomponent system to realize multi-color electroluminescence, which would promote the construction of colorful OLEDs by merely variating device architectures with minimum materials.