**Acknowledgements**

*Nanowires - Recent Progress*

*a*

*b*

*c*

*d*

*e*

**Table 1.**

*Average decay time.*

**Nanowire material** τ**<sup>1</sup>**

*Lifetime of the photo-generated charge in the level 1.*

*Lifetime of the photo-generated charge in the level 1.*

*component determined from the PL decays shown in Figure 5.*

*Weight relative of population of photo-generated charges contributing to level 1.*

*Weight relative of population of photo-generated charges contributing to level 1.*

not entangled, or at least close enough.

pristine PPV (τmean = 118 ps) and shorter than for pristine PVK (τmean = 342 ps). It can be noted that at an emission wavelength of 535 nm, whatever the kind of nanowires, blend or coaxial, the PL of the PPV component dominates because PPV has the shortest lifetime and a quantum yield slightly larger. In one hand, the system which shows the decay closer to PVK is PPV@PVK. Its longer average lifetime can be attributed to the photogenerated excitons in the PVK when considered as a donor. They have an important probability to diffuse to the acceptor PPV and to transfer their energy before any radiative recombination. In another hand, the system which shows the decay closer to PPV is PVK@PPV. It suggests that the emission by the PPV shell is due to the excitation of PPV excitons partly by the laser probe, and partly by the energy transfer from the photogenerated excitons in the PVK acting as a donor. The case of PVK-PPV blend decay is intermediate between the two coaxial configurations, a bit closer from the PVK@PPV arrangement. It suggests that for this blend, PPV and PVK segments do not deeply affect the exciton dynamics of each other, as expected when chains of both polymers are

*Photoluminescence decays times (in picosecond, with error bars estimated at about 10%) and yields of each* 

**a (ps)**

PPV 35 238 0.59 0.41 118 PVK 37 405 0.17 0.83 342 PPV-PVK blend 33 254 0.32 0.68 183 PVK@PPV 35 230 0.37 0.63 158 PPV@PVK 67 221 0.29 0.71 176

τ**2 b (ps)**

**P1 c (%)**

**P2 d (%)** τ**meane (ps)**

These results strongly support the analysis and the conclusion of the steadystate PL study, dominated by morphological issues in relation with the exciton diffusion length of PVK: thin PVK shell for the PPV@PVK nanowires, large PVK diameter for PVK@PPV nanowires, large PVK domains due to a poor intermixing between PPV and PVK obtained during the blending process. This work opens the way to develop alternative solution processing techniques to manage the local organization of donor-acceptor systems at the scale of the exciton diffusion

In this work, the template method with in-solution processes was exploited to control the respective organization of two polymers at the nanoscale in order to tune the donor-acceptor behavior, and then the photoluminescence properties of such nanowires. Two luminophores, PPV and PVK, were used for the fabrication of coaxial architectures and blend arrangement. The analysis of both steady-state and time-resolved photoluminescence study were analyzed by comparing the exciton diffusion length to the domain size of the nanowire shell,

**180**

length.

**5. Conclusion**

The authors would like to thank these colleagues at the Institute of Materials Jean Rouxel in Nantes: Jean-Luc duvail, Florian Massuyeau and Eric Faulques for help in optical study.
