IR fluorescent material for outdoor use
A commercial solution would be a dye like IRF940A (from QCR Solutions) with an excitation maximum at $\lambda_{\mathrm{exc}} = 405\,\mathrm{nm}$ and an  emission maximum at $\lambda_{\mathrm{em}} = 940\,\mathrm{nm}$. The supplier does not provide any information on the structure of the dye.
What compounds are promising candidates?
Ytterbium(III) complexes!
In a recent article,published in J. Photochem. Photobiol. A, 2015, *309, 65-71 (DOI), J. Legendziewicz and coworkers prepared a $\ce{Yb(III)}$ phthalocyanine with acetate as a chelating axial ligand and examined the optical properties in solution and in PMMA polymer. In PMMA, the compound shows a Soret band with a maximum at $\lambda_{\mathrm{abs}} = 350\,\mathrm{nm}$. Excitation in the Soret band result in emission with a maximum around around $\lambda_{\mathrm{em}} = 700\,\mathrm{nm}$.
Other examples for even larger wavelength differences, resulting from ligand-to-metal energy transfer are known  for $\ce{Yb(III)}$ complexes bound to eosines or fluoresceines as the primary chromophor.