The functionalization of semiconducting single-wall carbon nanotubes (SWCNTs) with luminescent sp 3 defects creates red-shifted emission features in the near-infrared and boosts their photoluminescence quantum yields (PLQYs). While multiple synthetic routes for the selective introduction of sp 3 defects have been developed, a convenient metric to precisely quantify the number of defects on a SWCNT lattice is not available. Here, we present a direct and simple quantification protocol based on a linear correlation of the integrated Raman D/G + signal ratios and defect densities as extracted from PLQY measurements. Corroborated by a statistical analysis of single-nanotube emission spectra at cryogenic temperature, this method enables the quantitative evaluation of sp 3 defect densities in (6,5) SWCNTs with an error of ±3 defects per micrometer and the determination of oscillator strengths for different defect types. The developed protocol requires only standard Raman spectroscopy and is independent of the defect configuration, dispersion solvent, and nanotube length.

easily processable (e.g., from solution and on flexible substrates), operate at low voltages, have long retention times, allow for a large number of distinguishable conductance states to be programmed, and should be easily readable and erasable in a controlled manner. [4] A wide range of organic semiconductors has been tested and employed for this purpose, often in field-effect transistor structures. [5] The operating mechanism usually depends on photoinduced charge trapping at the interface between the semiconductor and gate dielectric, thus leading to a threshold shift and a large ratio between the channel conductance before and after irradiatio n. [3c,6] A second possible route is mixing the semiconductor with a photochromic molecule that can act as a charge trap in one state but not the other and thus change the effective mobility of the semiconducting layer. [1a,7] A variety of light-switchable molecules were employed in such devices, e.g., diarylethenes or azobenz enes. [1a,8] Another well-known photochromic system is the spiropyran/merocyanine pair. [7d,9] Upon irradiation of spiropyran with ultraviolet (UV) light, its isomer merocyanine is formed. Merocyanine has a much higher dipole moment than spiropyran and due to its more extended π-conjugation absorbs light in the visible range. [9a] Heating as well as excitation with greenyellow light induces the reverse isomerization, which enables repeated switching between the two forms. One desirable application of such optical memory elements is wearable UV dosimeters that can track the total exposure to harmful ultraviolet radiation. [2,10] Practical devices of this kind require mechanical flexibility and low operating voltages. Ideally, these sensors should be blind to visible light and resettable, i.e., reusable. A variety of materials and sensor concepts have been explored in recent years including photoelectric (e.g., ZnO nanowire photodetectors) [11] and again photochromic (e.g., color change of a polyoxometalates) [12] sensors. Among them, mixed networks of single-walled carbon nanotubes (SWNTs) have been tested in photoelectric devices. Kim et al. found an increase of the resistance (by up to 50%) in a two-terminal device with a random network of SWNTs after UV exposure, which was caused by desorption of oxygen and thus decreased p-doping. [13] In general, nanomaterials such Nanohybrids of purified semiconducting single-walled carbon nanotubes and conjugated polymers with attached spiropyran moieties are created as photoresponsive materials for optical memory devices and ultraviolet (UV) light sensors. The hybrids respond to UV light exposure in air with photoisomerization of the spiropyran groups to merocyanine, resulting in significant and persistent p-doping of the nanotubes, as confirmed by photoluminescence quenching and trion emission. The increased carrier concentration after illumination and the inherently high mobility of carbon nanotubes enable an up to two orders of magnitude increased conductivity of the nanotube/polymer hybrid networks in s...

Efficient synthetic approaches for the incorporation of nitrogen into polyaromatic compounds (PACs) in different patterns as stabilising moiety for π‐extended systems and modification tool for optoelectronic properties remain a challenge until today. Herein, we developed a new versatile pathway to napthyridine‐based PACs as non‐symmetric and regioisomeric pendant to pyrazine‐based PACs. A combination of a gold‐catalysed synthesis of 2‐aminoquinolines and the development of an in situ desulfonation and condensation of these precursors are the key steps of the protocol. The shape and type of attached functional groups of the PACs can be designed in a late stage of the overall synthetic procedure by the chosen anthranile and backbone of the ynamide introduced in the gold‐catalysed step. Single‐crystal X‐ray diffraction and the investigation of electronic properties of the compounds show the influence of the attached substituents. All naphthyridine‐based PACs show halochromic behaviour implying their use as highly sensitive proton sensor in non‐protic solvents.

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