Highly color-stability flexible white organic light-emitting devices fabricated by color conversion method

Abstract

We demonstrate flexible white organic light-emitting diode (WOLED) with high color stability, which combines vacuum deposited blue flexible organic light-emitting diode (FOLED) with red surface color conversion material (CCM). Firstly, we utilize the novel multiple quantum well (MQW), which consists of the alternate layers of 2, 3, 5, 6-Tetrafluoro-7, 7, 8, 8-tetracyano-quinodimethane (F4-TCNQ) and 4, 4', 4"-tris-(N-3-methylphenyl-N-phenylamino) tripheny-lamine (m-MTDATA) as hole injection layer (HIL), through combining a new blue emitting material of N6, N6, N12, N12-tetrap-tolylchrysene-6, 12-diamine (NCA), to fabricate highly efficient blue FOLED. Then, the CCM of 4-(dicyanomethylene)-2-tert-butyl-6-(1, 1, 7, 7-tetramethyljul-oli-dyl-9-en-yl)-4H-pyran (DCJTB) is deposited on the outside of the ITO flexible substrate. Finally, the thickness of the color conversion film (CCF) is optimized to improve the color purity of flexible WOLED. The results demonstrate that at a driving voltage of 7 V, the CIE coordinates of (0.33, 0.27) which are very close to the white equal-energy area are obtained with the thickness of DCJTB of 120 nm. Moreover, the CIE coordinate migrations of the flexible WOLED are less than (±0.02, ±0.02) in a wide range of driving voltages (from 6 V to 11 V) for the device, indicating the flexible WOLED has excellent color stability.