吡啶类双偶极主体材料及有机电致磷光器件

doi:10.6023/A25080281

摘要/Abstract

在平板显示和白光照明领域, 同时具有高效率和低效率滚降仍然是有机电致发光器件(OLED)必须满足的关键要求. 因此以咔唑为空穴传输单元(p-型基团), 亚苯基作为连接单元, 将吡啶引入分子结构中作为电子传输单元(n-型基团), 通过邻位和间位的连接形式设计并制备了两种双偶极主体材料o-2CzPy和m-2CzPy. 这两种主体材料具有良好的热稳定性和双偶极电荷传输能力, 掺杂FIrpic和Ir(ppy)₃的蓝色和绿色磷光器件获得了高色纯度、高效率和低效率滚降. 其中, 基于o-2CzPy的蓝光器件最大外量子效率和电流效率分别达到了24.44%和45.16 cd•A⁻¹, 接近于目前文献报道的掺杂FIrpic蓝色磷光器件中的最佳数据. 此外, 基于o-2CzPy的绿光器件也获得了较高的外量子效率和电流效率, 分别为28.58%和96.91 cd•A⁻¹; 稳定的发光颜色, CIEy变化不超过0.0001. 这些结果表明这些主体材料有望在高效率且稳定的OLED显示领域中得到实际应用.

关键词: 磷光有机电致发光器件(PhOLEDs), 双偶极主体材料, 吡啶, 低效率滚降, 咔唑

Achieving an excellent device performance with low efficiency roll-off is still a crucial requirement for organic light-emitting diodes (OLED) in displays and white lighting applications. Therefore, we selected carbazole as the hole transporting group (p-type unit), phenylene as the linkage unit and pyridine as the electron transporting unit (n-type unit), to construct two bipolar host materials o-2CzPy and m-2CzPy, by varying the ortho- and meta-linking modes. Their chemical structures were confirmed by mass spectrometry (TOF-MS-EI), ¹H and ¹³C NMR spectroscopy, and elemental analysis. These two materials have good thermal stability with the thermal decomposition temperatures of than 360 ℃ and efficient hole- and electron-transporting properties. FIrpic and Ir(ppy)₃ based blue and green PhOLEDs incorporating o-2CzPy and m-2CzPy as hosts show pretty color purity, high efficiencies and low efficiency roll-off. Among them, the maximum current efficiency of 45.16 cd•A⁻¹ and external quantum efficiency of 24.44% were achieved for o-2CzPy based blue device, which are close to the best values for FIrpic-based blue PhOLEDs with single bipolar host reported in recent literatures. Furthermore, the o-2CzPy based green device achieved the high efficiencies of 28.58% and 96.91 cd•A⁻¹, and stable emission color of ΔCIEy≤0.0001. Even at the practical brightness of 1000 cd•m⁻² and 6000 cd•m⁻², the external quantum efficiencies of o-2CzPy hosted green device still keep as high as 28.03% and 24.70%, with the slight efficiency reduction of 1.9% and 13.6%. These excellent results indicate that these bipolar host materials may find practical applications in highly efficient and stable OLED displays.

Key words: phosphorescent organic light-emitting diodes (PhOLEDs), bipolar host materials, pyridine, low efficiency roll-off, carbazole

引用此文

徐冬青, 童海姗, 史路延, 张婷. 吡啶类双偶极主体材料及有机电致磷光器件[J]. 化学学报, 2026, 84(2): 240-247.

Dongqing Xu, Haishan Dong, Luyan Shi, Ting Zhang. Pyridine-Based Bipolar Host Materials for Phosphorescent Organic Light-emitting Diodes[J]. Acta Chimica Sinica, 2026, 84(2): 240-247.

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图/表 10

图1. 化合物o-2CzPy和m-2CzPy的结构和合成路线

Figure 1. The chemical structures and synthetic protocol of o-2CzPy and m-2CzPy

图2. o-2CzPy和m-2CzPy的DSC曲线(第二次加热)

Figure 2. DSC curves of the second heating cycle for o-2CzPy and m-2CzPy

图3. o-2CzPy和m-2CzPy在(a)二氯甲烷溶液中的紫外吸收和荧光发射光谱; (b) 2-甲基四氢呋喃溶液中的低温磷光光谱(77 K)

Figure 3. (a) Absorption and fluorescence spectra of o-2CzPy and m-2CzPy in CH2Cl2 at ambient temperature; (b) Low-temperature phosphorescence spectra of o-2CzPy and m-2CzPy in 2-MeTHF at 77 K

Compd.	$ \lambda_{\max }^{\mathrm{abs}}$/nm	$ \lambda_{\text {max }}^{\mathrm{em}}$/nm	E_g^a/eV	E_T^b/eV	HOMO/eV	T_g/℃	T_d/℃
Compd.	CH₂Cl₂		E_g^a/eV	E_T^b/eV	HOMO/eV	T_g/℃	T_d/℃
o-2CzPy	293, 324, 338	417	3.48	2.74	－5.59	71	365
m-2CzPy	293, 326, 340	431	3.47	2.64	－5.61	95	417

表1. o-2CzPy和m-2CzPy的物理性质数据

Table 1. Summary of physical parameters for o-2CzPy and m-2CzPy

图4. o-2CzPy和m-2CzPy的循环伏安曲线

Figure 4. Cyclic voltammograms of o-2CzPy and m-2CzPy at ambient temperature

图5. o-2CzPy和m-2CzPy的HOMO和LUMO电子云分布和优化分子构型

Figure 5. Theoretical calculated HOMO and LUMO orbitals, and molecular structures of o-2CzPy and m-2CzPy

图6. o-2CzPy和m-2CzPy的(a)单空穴和(b)单电子器件的电流密度-电压曲线

Figure 6. The current density versus voltage curves for o-2CzPy and m-2CzPy based (a) hole-only and (b) electron-only devices

图7. 基于o-2CzPy器件B1的(a)电流密度-电压-亮度和(b)效率曲线

Figure 7. (a) The J-V-B characteristics and (b) efficiency curves for o-2CzPy hosted blue device B1

Device	Host	Dopant	V_on^a/V	L_max/(cd•m⁻²)	η_c^b/(cd•A⁻¹)	η_p,max/(lm•W⁻¹)	η_ext^b/%	FWHM/nm	CIE (x, y) at 6 V	Φ_PLQY^c/%	τ^c/μs
B1	o-2CzPy	FIrpic	2.9	19880	45.16, 40.54, 28.62	37.60	24.44, 21.94, 15.49	46	(0.14, 0.28)	92.0	2.21
G1	o-2CzPy	Ir(ppy)₃	2.9	108810	96.91, 95.05, 83.74	88.22	28.58, 28.03, 24.70	56	(0.28, 0.63)	95.4	0.92
G2	m-2CzPy	Ir(ppy)₃	3.1	59386	83.84, 78.99, 62.77	73.56	24.48, 23.06, 18.33	60	(0.29, 0.63)	80.8	1.14

表2. 基于o-2CzPy和m-2CzPy的电致发光器件数据总结

Table 2. Electroluminescent performance for o-2CzPy and m-2CzPy based blue and green devices

图8. 基于o-2CzPy和m-2CzPy器件G1和G2的(a)电流密度-电压-亮度和(b)效率曲线

Figure 8. (a) The J-V-B characteristics and (b) efficiency curves for o-2CzPy and m-2CzPy hosted green devices G1 and G2

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