Lee Illhwan, Park Jae Yong, Hong Kihyon, Son Jun Ho, Kim Sungjun, Lee Jong-Lam
Department of Material Science and Engineering, POSTECH, Hyojadong, Namgu San 31, Pohang, Kyungbuk, Republic of Korea.
Department of Bioengineering, UC Berkeley, 442 Stanley Hall, Berkeley, California, USA.
Nanoscale. 2016 Mar 28;8(12):6463-7. doi: 10.1039/c5nr07438j.
Three primary colors, cyan, yellow, and green, are obtained from Ag nano-dot embedded organic light emitting diodes (OLEDs) by localized surface plasmon resonance (LSPR). By changing the thickness of the Ag film, the size and spacing of Ag nano-dots are controlled. The generated light from the emissive layer in the OLEDs interacts with the free electrons near the surface of the Ag nano-dots, which leads to LSPR absorption and scattering. The UV-visible absorption spectra of glass/ITO/Ag nano-dot samples show intense peaks from 430 nm to 520 nm with an increase of Ag nano-dot size. And also, the Rayleigh scattering spectra results show the plasmon resonance wavelength in the range of 470-550 nm. The effect of the LSPR of Ag nano-dots on the change of emission color in OLEDs is demonstrated using 2 dimensional finite-difference time-domain simulations. The intensity of the electro-magnetic field in the sample with 5 nm-thick Ag is low at the incident wavelength of 500 nm, but it increases with the incident wavelength. This provides evidence that the emission color change in OLEDs originates from LSPR at the Ag nano-dots. As a result, the emission peak wavelength of OLEDs shifted toward longer wavelengths, from cyan to yellow-green, with the increase of Ag nano-dot size.
通过局域表面等离子体共振（LSPR），从嵌入银纳米点的有机发光二极管（OLED）中获得了三种原色，即青色、黄色和绿色。通过改变银膜的厚度，可以控制银纳米点的尺寸和间距。OLED发光层产生的光与银纳米点表面附近的自由电子相互作用，从而导致LSPR吸收和散射。玻璃/氧化铟锡/银纳米点样品的紫外-可见吸收光谱显示，随着银纳米点尺寸的增加，在430纳米至520纳米处出现强烈的峰值。此外，瑞利散射光谱结果表明等离子体共振波长在470-550纳米范围内。利用二维时域有限差分模拟证明了银纳米点的LSPR对OLED发光颜色变化的影响。在500纳米的入射波长下，银厚度为5纳米的样品中的电磁场强度较低，但随着入射波长的增加而增加。这证明了OLED中的发光颜色变化源于银纳米点处的LSPR。结果，随着银纳米点尺寸的增加，OLED的发射峰值波长向更长波长移动，从青色变为黄绿色。
