Addressable, large-area nanoscale organic light-emitting diodes.
Addressable, large-area nanoscale organic light-emitting diodes.
复制标题
可寻址、大面积纳米级有机发光二极管。
作者：
Scott P. Price;Joel Henzie;Teri W. Odom
在制造和加工用于全彩色显示器的宏尺度有机发光二极管(OLED)方面的进展引起了人们对在纳米尺度上产生OLED的兴趣。减小OLED的尺寸可以产生更高的单位面积器件密度，从而允许制造更高分辨率的显示器，这些显示器具有更强的缺陷容忍度，在近距离可见。此外，纳米OLED(其有效面积约为100 nm)可能被用作高分辨率成像技术和纳米光学光刻的亚波长光源。尽管电子束光刻(EBL)等系列方法已被用于制造纳米OLED阵列，但这些仅限于原型的方法的缺点是图案化面积小(0.2 mm)和低密度(1.10像素/mm)。7]在这里，我们报道了大面积(Cm)的纳米OLED阵列的制备，其像素密度比使用串联技术制备的阵列具有更高的像素密度。我们使用软纳米光刻--使用复合聚二甲基硅氧烷(PDMS)印章通常可以产生小于500 nm特征尺寸的平行图案化方法--在支撑在透明导电基板上的负性光致抗蚀剂中生成直径为250 nm的孔阵列。然后，电致发光分子被组装在这些孔中，以制造纳米OLED。我们获得了每毫米超过10像素的像素密度，而缺陷密度仅取决于PDMS掩模中的缺陷。此外，我们还证明了这些纳米OLED是一维可寻址的。纳米OLED的进展在很大程度上是通过定义电触点的面积来实现的。通过减小氧化铟锡(ITO)阳极的有效面积，纳米球光刻技术已被用于制造亚100 nm像素。SiO_2[6]或Si3N_4[7]等绝缘材料薄膜中的纳米孔(直径60-200 nm)已被用来定义基于聚荧烯和poly-[2-methoxy-5-(2’-ethylhexyloxy)-1，4-phenylene乙烯的纳米OLED(MEHPPV)。尽管EBL可以限制阳极的有效尺寸，但纳米OLED不能单独寻址，因为它们都是在相同的电子背板上图案化的。其他报告使用软接触叠层将阴极图案化为宽度小至150 nm的金色电子ACHTUNGTRENNUNG导线，以生产MEHPPV OLED。基于电致发光联吡啶配合物RuACHTUNGTRENNUNG[(Bpy)3]的OLED器件受到了人们的关注，因为这种分子是一个高效而明亮的发射体。基于Ru ACHTUNGTRENNUNG[(Bpy)3 ACHTUNGTRENNUNG(ClO4)2]的可寻址1D阵列已经在玻璃基板上被制造出来，该玻璃基板上以1.1 mm的间距用五条0.9 mm线或ITO的“指状电极”图案化。17]虽然单独的线被接触，但一个缺点是在该制造过程中使用的湿法蚀刻步骤在ITO线中产生小缺陷。在厘米区域上形成可寻址的纳米OLED图案的能力对于生产实际设备和测试将光发射限制在纳米尺度的可能性至关重要。图1显示了我们制备RuACHTUNGTRENNUNG[(Bpy)3 ACHTUNGTRENNUNG(BF4)2]基纳米OLED的简单步骤。苏-8，一种绝缘材料
Advances in the fabrication and processing of macroscale organic light-emitting diodes (OLEDs) for full-color displays have created interest in generating OLEDs at the nanoscale. Reducing the size of an OLED can produce higher device densities per unit area, which allows the manufacture of higher resolution displays that are more defect tolerant and viewable at close range. Furthermore, nanoOLEDs (those whose active area is on the order of 100 nm) could potentially be used as subwavelength light sources for high-resolution imaging techniques and for nanooptical lithography. Although serial approaches such as electronbeam lithography (EBL) have been used to fabricate arrays of nano-OLEDs, drawbacks of these prototype-only methods include small patterned areas ( 0.2 mm) and low densities (1 .10 pixels per mm). 7] Here we report the fabrication of nano-OLED arrays over large areas ( cm) and with higher pixel densities than those prepared using serial techniques. We have used soft nanolithography—parallel patterning methods that can routinely produce feature sizes less than 500 nm using composite poly(dimethylsiloxane) (PDMS) stamps—to generate arrays of 250-nm-diameter holes in negative photoresist supported on a transparent conducting substrate. Electroluminescent molecules were then assembled within these holes to produce nano-OLEDs. We achieved pixel densities exceeding 10 pixels per mm with defect densities that depended only on imperfections in the PDMS mask. Moreover, we have demonstrated that these nano-OLEDs are addressable in one dimension. Progress toward nano-OLEDs has largely been achieved by defining the area of the electrical contacts. Nanosphere lithography has been used to fabricate sub-100-nm pixels by reducing the active area of the indium tin oxide (ITO) anode. Nanoscale holes (60–200 nm in diameter) within films of insulating materials such as SiO2 [6] or Si3N4 [7] have been used to define nano-OLEDs based on polyfluorene and poly-[2-methoxy-5-(2’-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV). Although EBL could confine the effective size of the anode, the nano-OLEDs could not be individually addressed because they were all patterned on the same electrical back plane. Other reports used soft-contact lamination to pattern the cathode into lines of gold elecACHTUNGTRENNUNGtrodes with widths as small as 150 nm to produce MEHPPV OLEDs. OLED devices based on the electroluminescent ruthenium bipyridyl complex RuACHTUNGTRENNUNG[(bpy)3] have received attention because this molecule is an efficient and bright emitter. Addressable 1D arrays of Ru ACHTUNGTRENNUNG[(bpy)3 ACHTUNGTRENNUNG(ClO4)2]-based OLEDs have been fabricated on glass substrates patterned with five 0.9-mm lines or “finger electrodes” of ITO on a 1.1-mm pitch. 17] Although individual lines were contacted, one drawback was that the wet-etching step used in this fabrication procedure generated small defects in the ITO lines. The ability to pattern addressable, nano-OLEDs over cm areas is critical for producing practical devices and for testing the possibilities of confining light emission to nanoscale dimensions. Figure 1 shows our simple procedure to fabricate RuACHTUNGTRENNUNG[(bpy)3 ACHTUNGTRENNUNG(BF4)2]-based nano-OLEDs. SU-8, an insulating