Assessment of Anisotropic Semiconductor Nanorod and Nanoplatelet Heterostructures with Polarized Emission for Liquid Crystal Display Technology
Assessment of Anisotropic Semiconductor Nanorod and Nanoplatelet Heterostructures with Polarized Emission for Liquid Crystal Display Technology
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DOI：
10.1021/acsnano.5b07949
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发表时间：
2016-06-01
期刊：
影响因子：
17.1
通讯作者：
Talapin, Dmitri V.
中科院分区：
文献类型：
--
作者：
Cunningham, Patrick D.;Souza, Joao B., Jr.;Talapin, Dmitri V.
半导体纳米棒可以发射效率超过80%的线偏振光。通过单棒光谱证实，这些系统中的光的偏振可以根据跃迁偶极矩的各向异性和介电限制效应来解释。在这里，我们报道了宏观半导体聚合物复合薄膜中的发射极化，该复合薄膜包括CdSe/CdS纳米棒和胶体CdSe纳米片。各向异性纳米晶分散在聚甲基丙烯酸丁酯-甲基丙烯酸异丁酯(PBiBMA)的聚合物薄膜中，可以通过机械拉伸获得单向排列的阵列。获得了高度的取向，对应于0.87的取向系数，并且大面积表现出偏振发射，对比度I平行/I垂直=5.6，使得这些薄膜适合用于液晶显示(LCD)设备。令人惊讶的是，我们观察到了具有量子阱电子结构的二维CdSe纳米片的显著的光学各向异性和发射偏振。排列的纳米棒阵列作为光学漏斗，吸收非偏振光并重新发射从深绿色到红色的光，量子效率超过90%，线偏振程度很高。我们的结果最终证明了各向异性纳米结构用于LCD背光的好处。与具有随机取向纳米结构的发射层相比，具有定向排列的CdSe/CDS点在棒和棒中棒纳米结构的聚合物薄膜的亮度提高了2倍以上。这种效应可以解释为单个纳米结构的线偏振发光和定向发射的结合。
Semiconductor nanorods can emit linear-polarized light at efficiencies over 80%. Polarization of light in these systems, confirmed through single-rod spectroscopy, can be explained on the basis of the anisotropy of the transition dipole moment and dielectric confinement effects. Here we report emission polarization in macroscopic semiconductor polymer composite films containing CdSe/CdS nanorods and colloidal CdSe nanoplatelets. Anisotropic nanocrystals dispersed in polymer films of poly butyl-co-isobutyl methacrylate (PBiBMA) can be stretched mechanically in order to obtain unidirectionally aligned arrays. A high degree of alignment, corresponding to an orientation factor of 0.87, was achieved and large areas demonstrated polarized emission, with the contrast ratio I-parallel to/I-perpendicular to= 5.6, making these films viable candidates for use in liquid crystal display (LCD) devices. To some surprise, we observed significant optical anisotropy and emission polarization for 2D CdSe nanoplatelets with the electronic structure of quantum wells. The aligned nanorod arrays serve as optical funnels, absorbing unpolarized light and re-emitting light from deep-green to red with quantum efficiencies over 90% and high degree of linear polarization. Our results conclusively demonstrate the benefits of anisotropic nanostructures for LCD backlighting. The polymer films with aligned CdSe/CdS dot-in-rod and rod-in-rod nanostructures show more than 2-fold enhancement of brightness compared to the emitter layers with randomly oriented nanostructures. This effect can be explained as the combination of linearly polarized luminescence and directional emission from individual nanostructures.