Photoluminescence enhancement of semiconducting-carbon-nanotubes-based thin films

Abstract

Semiconducting single wall carbon nanotubes (s-SWNT) are unique monodimensional material of particular interest in photonics for their direct band-gap, allowing tunable near-IR luminescence from electron-hole recombinaison. However, the presence of metallic nanotubes and impurities in real carbon nanotubes samples creates several non radiative relaxation mechanisms, leading to an effective quenching of s-SWNT photoluminescence and limiting their usability in photonics devices. Recently, we have developed a process to selectively extract s-SWNT and embedded them in polyfluorene (PFO) thin films. A removal of metallic nanotubes leads to an enhancement of the photoluminescence properties, with a 6-fold increase of the photoluminescence intensity of (8,6) s-SWNT. Development of nanotubes based photonics devices is also reported. The SWNT-based layer was inserted between two Bragg mirrors to form a Fabry-Perot cavity, leading to a huge photoluminescence enhancement by a factor of 30 in comparison with an identical film and by a factor of 180 in comparison with a non s-SWNT enriched film.

Advanced carbon nanotubes functionalization

“…While the aryl functionalization described in Section 3.2 efficiently activates such dark excitonic state, it still degrades the crystalline structure of the tubes. To escape this boundary, SWNTs have been embedded in special optical environments such as cavities [162], [163] or photonic crystals [164] to exploit their ad-hoc designed electromagnetic modes. Another suitable approach comprises plasmons, the special electromagnetic modes arising from the collective free-electrons oscillations in metals and localized close to the metal surface.…”

Integration of Semiconducting Carbon Nanotubes Within a Silicon Photonic Molecule

“…Previously reported light emission enhancement from nanotubes was by embedding a layer of CNT-PFO between two dielectric mirrors, formed by a SiO 2 /Si 3 N 4 multilayer-stack, which created a Fabry-Perot cavity and resulted in reinforced light emission [25]. A more clear demonstration later in a silicon 2D photonic cavity [14] has shown that CNTs PL emission is largely enhanced with sharp resonance peaks when CNTs are placed in or near cavity centre, otherwise no resonance emission peaks for off cavity can appear.…”

Carbon nanotube for photonics: light emission in silicon and optical gain

“…Carbon nanotube thin films and their subsequent integration into photonic devices was seldomly studied, with few results. 23,24 In fact, while s-SWNT individually displays very strong photonic properties, metallic carbon nanotubes (m-SWNT), catalytic impurities and bundled s-SWNT remaining in samples quenches photoluminescence by non radiative desexcitation paths, from m-SWNT interactions or s-SWNT exciton transfert. 25,26 The extraction of s-SWNT is a real challenge, and in recent years, several approachs to extract them from nanotube powders have been explored, using for instance chemical functionalization, DNA, polymers wrapping and density gradient ultracentrifugation techniques.…”