Cho et al. Nanoscale Research Letters 2011, 6:578 http://www.nanoscalereslett.com/content/6/1/578 Page 4 of 6 Figure 3 Cross-sectional SEM micrograph of micro and nano- complex polymer structure formed on LED device with spin coating speed of (a) 1,000 rpm, (b) 3,000 rpm, and (c) 5,000 rpm. Figure 4 Scanning electron microscopy (SEM) image of (a) cross-sectional view of the light emitting diode (LED) that was grown on the patterned sapphire substrate; SEM image of surface of the LED device after the reactive ion etching process in the (b) top view and (c) tilt view. micro- and nanoscale complex polymer structures. PSS were used for both LED devices. The EL measurement was taken from one randomly selected device, measured ten times, and then averaged. As shown in Figure 5a, the EL emission of the LED structure with micro- and nanoscale complex polymer structures increased up to 13%. This increase in photon extraction efficiency is additional; thus, it is very meaningful since the LED structure was grown on a PSS wafer to increase the photon extraction efficiency up to 30% [11,12]. The