Microcavity effects and optically pumped lasing in single conjugated polymer nanowires

Abstract

Conjugated polymers have chemically tuneable opto-electronic properties and are easily processed, making them attractive materials for photonics applications. Conjugated polymer lasers, in a variety of resonator geometries such as microcavity, micro-ring, distributed feedback and photonic bandgap structures, have been fabricated using a range of coating and imprinting techniques. Currently, one-dimensional nanowires are emerging as promising candidates for integrated, subwavelength active and passive photonic devices. We report the first observation of optically pumped lasing in single conjugated polymer nanowires. The waveguide and resonator properties of each wire are characterized in the far optical field at room temperature. The end faces of the nanowire are optically flat and the nanowire acts as a cylindrical optical cavity, exhibiting axial Fabry-Pérot mode structure in the emission spectrum. Above a threshold incident pump energy, the emission spectrum collapses to a single, sharp peak with an instrument-limited line width that is characteristic of single-mode excitonic laser action.

Advances in small lasers

“…These materials can be readily prepared as thin films (e.g., with thicknesses << 1 µm) by solution-based processes. In some cases, structures providing optical feedback can even form via self-assembly [33][34][35] . Moreover, the gain spectrum of these materials can be readily tuned by targeted modifications of chemical structure, composition and characteristic dimension (Fig.…”

“…Small nanowire lasers have only been demonstrated under strong optical pumping with recent examples exhibiting complex nanowire growth 29,30 . Self-assembled organic semiconductor nanowires have also yielded small lasers (300 nm diameter, 6 µm length) without the need for lithographic patterning 33 . In a similar fashion, internal reflection in micro-crystals of organic semiconductors has been used to define Fabry-Perot type cavities 35 .…”

Solution-processed, high-performance n-channel organic microwire transistors

“…To date, however, very few solutionprocessable, air-stable organic n-channel semiconductors matching the performance of amorphous silicon (a-Si) ( Ն 0.1 cm 2 /Vs) have been reported (4)(5)(6)(7)(8). Organic semiconductor nano/microwires (NWs/MWs) have recently emerged as promising building blocks for various electronic and optical applications such as light-emitting diodes (LEDs) (9), field-effect transistors (FETs) (10), photoswitches (11), vapor sensors (12), solar cells (13), nanoscale lasers (14), optical waveguides (15), and memory devices (16). These unique materials combine the high-performance of singlecrystalline structures with solution-processability by dispersion (17,18).…”

Fluorene-based macromolecular nanostructures and nanomaterials for organic (opto)electronics

“…They assessed their waveguiding performance and emission tenability in the whole visible range and demonstrated the enhancement of the fibre forward emission. The propagation loss of waveguiding capability of PF-23 (F8BT) had a loss coefficient γ of 3 × 10 2 cm −1 , which is lower than the values reported for semicrystalline PFO (PF-01b) nanowires [61] and thin films (greater than 2 × 10 3 cm −1 ). PFO (PF-01b) nanowire thin films have been used for electrochemiluminescence (ECL) to investigate the mechanisms of charge carrier reactions [253].…”

“…AAO templates are another simple, low-cost and effective method for one-dimensional nanostructures with the special apparatus to generate PFs nanowires that were reported by Redmond and coworkers [17,61,[252][253][254][255]. A representative PF-19 (F8T2) nanowire has an average length of 15 μm and diameter of 200 nm.…”