Park Ho-Cheol, Park Jong-Wook, Oh Seong-Geun
Department of Chemical Engineering, Hanyang University, Seoul 133-791, Korea.
J Nanosci Nanotechnol. 2009 Dec;9(12):7260-4. doi: 10.1166/jnn.2009.1658.
New type of White-Light Emitting Diode (WOLED) that emits three primary colors of red, green and blue has been demonstrated. WOLED is properly laid out with emitting layers so that all three wavelengths of light can be emitted by using fit energy level, and the organic functional layer named white balanced layer (WBL) is introduced. As for the material used as WBL, the experiment used NPB that has electron blocking effect with its large LUMO value. The color purity of such WOLED can be easily adjusted through the adjustment of the number of electron carriers injected into light emitting layer. Therefore, the experiment organized WOLED by using doping concentration of highest efficiency demonstrated by RGB single color device, and adjusted color purity of white color through the adjustment of WBL thickness adjustment. In the case of WOLED device that possesses the device structure of ITO/m-MTDATA 40 nm/NPB 5 nm/NPB + P-1 (3%) 3 nm/NPB 0.1 nm/Alq3 + C-545T(5%) 0.5 nm/IDE-120 + IDE-105(7%) 35 nm/LiF 1 nm/Al 150 nm in this study, color coordinate was (0.341, 0.424) and light emitting efficiency was 16.5 cd/A at current density 10 mA/cm2, so the WOLED demonstrated highly efficient characteristics of over commercial level.
已证明了一种新型的发白光的发光二极管（WOLED），它能发出红、绿、蓝三种原色。WOLED通过发射层进行合理布局，以便利用合适的能级发射出所有三种波长的光，并引入了名为白平衡层（WBL）的有机功能层。至于用作WBL的材料，实验使用了具有电子阻挡效应且LUMO值较大的NPB。通过调整注入发光层的电子载流子数量，可以轻松调节这种WOLED的色纯度。因此，该实验利用RGB单色器件所展示的最高效率掺杂浓度来构建WOLED，并通过调整WBL厚度来调节白色的色纯度。在本研究中，对于具有ITO/m-MTDATA 40 nm/NPB 5 nm/NPB + P-1（3%）3 nm/NPB 0.1 nm/Alq3 + C-545T（5%）0.5 nm/IDE-120 + IDE-105（7%）35 nm/LiF 1 nm/Al 150 nm器件结构的WOLED器件，在电流密度为10 mA/cm2时，色坐标为（0.341, 0.424），发光效率为16.5 cd/A，因此该WOLED展示出超过商业水平的高效特性。
