Blue fluorescent OLED materials and their application for high-performance devices

Figures & data

Figure 1 Structures of DSA host and stylylamine dopant (Ar and R denote an arylene group and a substituent, respectively).

Figure 2 Structures of arylamine dopants (Ar and R denote an arylene group and a substituent, respectively).

Figure 3 Energy diagram and excited level of each layer in an OLED with an EEL.

Table 1 Performance of BD-6 and BD-7 devices with or without an EEL (J = 10 mA cm⁻²).

Device	BD	EEL	Voltage (V)	CIEx	CIEy	L/J (cd/A)	EQE (%)	Peak^a (nm)	LT50^b (h)
1	BD-6	—	3.8	0.147	0.116	7.1	6.8	450	8000
2	BD-6	EEL-2	3.8	0.146	0.115	9.0	8.7	451	10 000
3	BD-7	—	3.9	0.144	0.080	5.5	7.1	452	11 000
4	BD-7	EEL-2	3.8	0.143	0.078	6.5	8.6	452	9000

a Peak wavelength of EL spectrum.

b Initial luminance of 500 cd m⁻², constant current driving condition at room temperature.

Figure 4 Transient EL curves of devices 1 and 3: (a) transient EL curves as a function of log-scaled time; (b) inverse square root of transient EL intensity as a function of linear-scaled time.

Figure 5 S′ of BD-C doped host film with a thickness of 100 nm.

Table 2 Material properties of the four BDs.

BD	EgS (eV)	IP (eV)	Ovality	kx	kz	S	S′
A	0.00	0.00	1.84	3.10×10^−1	1.27×10^−1	−0.245	0.830
B	0.02	0.05	1.89	2.41×10^–1	7.71×10^–2	−0.293	0.862
C	−0.01	−0.09	1.94	3.65×10^–1	8.64×10^–2	−0.341	0.894
D	−0.01	−0.11	2.06	3.42×10^–1	4.64×10^–2	−0.405	0.936

Table 3 Device performance at a current density of 10 mA cm⁻².

Device	Voltage (V)	CIEx	CIEy	L/J (cd/A)	EQE (%)
BD-A	3.39	0.145	0.120	8.39	7.97
BD-B	3.37	0.145	0.104	7.87	8.33
BD-C	3.38	0.143	0.128	10.8	9.83
BD-D	3.38	0.143	0.127	11.0	10.1

Figure 6 (a) V-J curves and (b) J-L/J curves.

Figure 7 (a) Impedance spectroscopy results and (b) transient EL decay curves.

Figure 8 Calculated photonic mode density of a fluorescent blue device.

Figure 9 Relationship between orientation factor S′ and external quantum efficiency of an OLED (blue circle: results of BD-A–D; red square: modified BDs; red dotted line: ideal case with 100% of PLQY, 40% of singlet exciton formation ratio).