**2. Materials and techniques**

## **2.1 Materials**

Poly(N-vinylcarbazole) PVK powder, chloroform, methanol, used for the synthesis of the studied compounds were purchased from Sigma Aldrich, Merk, and Fluka. The materials were used as received. The PPV precursor was synthesized by addition of 33 mL of tetrahydrothiophenium in the dichloroparaxylene dissolved in methanol. The aqueous solution of PPV precursor was dialyzed with deionized water for several days. The PPV precursor was kept at 0°C in the dark. The mass concentration of the PPV precursor is about 2.4 mg mL. Commercial AAO membranes purchased from Whatman (anodisc 13) have been used. They are 60 μm thick with a real pore diameter showing a polydispersity between200 nm and around 250 nm as revealed by SEM analysis.

## **2.2 Fabrication of the coaxial NWs**

The coaxial NWs were fabricated by a wetting template method in anodic alumina oxide (AAO) nanoporous template. For the synthesis of coaxial NWs, two steps of wetting are required. The first step consists in the wetting of AAO membrane with the PPV precursor in methanol solution. To obtain PPV nanotubes, the concentration of PPV precursor in methanol was chosen at 1.2 mg/mL and 200 μL of this solution was drop-casted on AAO membrane, as described elsewhere. The precursor embedded in AAO membrane was then thermally converted under a dynamic secondary vacuum (≈10–6 Torr) for 4 h to obtain PPV. The coaxial nanowires are then obtained by a secondary-template strategy. The AAO membrane containing PPV nanotubes was wetted with the solution containing PVK dispersed in chloroform. The wetted templates were left overnight under ambient condition to allow solvent evaporation. For some characterization, the AAO templates containing coaxial NWs was completely etched in H3PO4 (25 wt %) overnight and washed several time with DI water. The coaxial NWs were homogeneously dispersed in DI water solution by ultrasonication during 10 s with a power of 140 W (Fisher Scientific FB 15052). Ultrasonication results in the shortening of the nanowire length.
