National Creative Research Initiative Center for Block Copolymer Self-Assembly, Department of Chemical Engineering and Polymer Research Institute, Pohang University of Science and Technology, Kyungbuk 790-784, Korea.
Langmuir. 2010 Apr 6;26(7):5110-4. doi: 10.1021/la9035858.
Broadband antireflection (AR) covering from visible light to near infrared (NIR) wavelengths (400-2000 nm) was obtained by using three sequential spin-coatings of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) copolymers with different volume fractions of PMMA block (f(PMMA)) on a glass. PS-b-PMMA having the lowest PMMA volume fraction (f(PMMA) approximately 0.3) among three PS-b-PMMAs was first spin-coated on a glass substrate. After spin-coating, the film was irradiated by ozone to prevent dissolution during the next spin-coating process. Then PS-b-PMMA with the next larger volume fraction of PMMA block (f(PMMA) approximately 0.46) was spin-coated and irradiated again by ozone. Finally, PS-b-PMMA with the largest volume fraction of PMMA block (f(PMMA) approximately 0.69) was spin-coated. After three sequential spin-coatings, the entire film was irradiated under UV followed by rinsing with acetic acid, which removed PMMA blocks. This process allowed us to have the triple layers with spongelike nanoporous structures where the refractive index increases from the top to the bottom of the film. The morphology of the triple-layered nanoporous block copolymer films was investigated by scanning electron microscopy. The nanoporous film exhibited excellent broadband AR at wavelengths from 400 to 2000 nm. The measured reflectance curves are in good agreement with the calculation from the characteristic matrix theory. This AR coating would be used for the development of solar cells with high power convergence efficiency.
通过在玻璃上依次旋涂三种不同 PMMA 嵌段体积分数（f(PMMA)）的聚苯乙烯-聚甲基丙烯酸甲酯（PS-b-PMMA）共聚物，实现了从可见光到近红外（NIR）波长（400-2000nm）的宽带抗反射（AR）覆盖。在三种 PS-b-PMMA 中，PMMA 嵌段体积分数最低（f(PMMA)约为 0.3）的 PS-b-PMMA 首先旋涂在玻璃基底上。旋涂后，用臭氧照射薄膜，以防止在下一次旋涂过程中溶解。然后，旋涂 PMMA 嵌段体积分数更大（f(PMMA)约为 0.46）的 PS-b-PMMA 并再次用臭氧照射。最后，旋涂 PMMA 嵌段体积分数最大（f(PMMA)约为 0.69）的 PS-b-PMMA。经过三次连续旋涂后，整个薄膜在紫外光下照射，然后用乙酸冲洗，去除 PMMA 嵌段。该过程允许我们拥有三层具有海绵状纳米多孔结构的薄膜，其中折射率从薄膜的顶部到底部逐渐增加。通过扫描电子显微镜研究了三层纳米多孔嵌段共聚物薄膜的形态。纳米多孔薄膜在 400-2000nm 波长范围内表现出优异的宽带 AR。测量的反射率曲线与特征矩阵理论的计算吻合较好。这种 AR 涂层将用于开发具有高功率会聚效率的太阳能电池。
