Chromaticity Tunable Realizable Solution Process Single Layer White Organic Light-Emitting Diode

The achievement of white color emission required simultaneous emission of optimized composition of blue, green, and red colors or at least two supplementary colors with similar distribution of emission intensities covering the entire visible spectrum ranging from 400 to 700 nm in solution-processable white organic light-emitting diodes (W-OLEDs). In view of this information, different concentrations of polyvinylcarbazole (PVK), red polymer Nile Red, and blue polymers such as poly(9,9-dioctylfluorenyl-2,7-diyl) (PF) and spirobifluorene derivative SPB-02T were utilized to obtain white light emission in single-layer W-OLEDs. Coupled emissions of these materials with blue luminescence from PF and SPB-02T and reddish emission from Nile Red presented white color due to energy transfer between the two polymers. Efficient solution-processed W-OLED devices were fabricated using a single layer light-emitting film with optimized concentration of ternary blends. W-OLED device performances were analyzed for their charge transport behavior depending on concentration of ternary blend. When it has been looked from the viewpoint of the closest to white color coordinates (0.33, 0.33), the W-OLED device named mpn4 with PVK:SPB-02T:Nile Red was the closest (0.33, 0.27). In consideration of energy transaction, voltage dependency in electroluminescence spectra proved that the existence of energy transfer in the mpn4-based W-OLEDs.