Porous carbons that are three-dimensionally periodic on the scale of optical wavelengths were made by a synthesis route resembling the geological formation of natural opal. Porous silica opal crystals were sintered to form an intersphere interface through which the silica was removed after infiltration with carbon or a carbon precursor. The resulting porous carbons had different structures depending on synthesis conditions. Both diamond and glassy carbon inverse opals resulted from volume filling. Graphite inverse opals, comprising 40-angstrom-thick layers of graphite sheets tiled on spherical surfaces, were produced by surface templating. The carbon inverse opals provide examples of both dielectric and metallic optical photonic crystals. They strongly diffract light and may provide a route toward photonic band-gap materials.

A new giant actuation mechanism is demonstrated for sheets of carbon single‐wall nanotubes that produces a 3 % actuator stroke in the in‐plane direction, and amplification to over 300 % in the thickness direction. Electrochemically generated gas bubbles form in the internal pores of the nanotube sheets (see Figure), producing a pneumatic‐type actuation at low application voltages.

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The world's first directly patternedfull‐color OLED microdisplay with > 2600 ppi will be presented. This display is built on a 1920x1200‐pixel CMOS backplane and uses RGB emitters, eliminating the need for color filters. This technology results in very‐high‐luminance microdisplays, ideally suited for wearable AR and VR applications.

The performance details of a full‐color 2K x 2K resolution OLED microdisplay with a brightness of 5,000 cd/m2will be presented. The microdisplay was built on a CMOS‐based silicon backplane using direct patterning of the primary‐color OLED emitters. Additionally, the color gamut of the microdisplays were increased to meet sRGB requirements. Such microdisplays will be ideally suited for wearable VR (virtual reality) and AR (augmented reality) applications.