Cover Image, Volume 51, Issue 9


original image

Crystal needles of small molecules embedded in a polymer film are produced by spin-coating the blend solution of PFO and EPPTC in chloroform onto a glass substrate, as presented by Xinping Zhang, Fei Dou, and Hongmei Liu on page 749. Microscopic characterization shows controllable sizes of the crystal needles with changing the spincoating speed. The spatial mapping of the near-field PL spectrum shows new emission on the heterointerface between the PFO and the EPPTC molecules on the outer shells of the crystal needles. The new spectral feature is resolved between the intrinsic emission of individual molecules and pure aggregates of EPPTC and exhibits a rather long lifetime. This results from the formation of charge-transfer states as electrons transfer from PFO to the H-aggregated EPPTCmolecules.