Unconditionally stable indole-derived glass blends having very high photorefractive gain: The role of intermolecular interactions

Rocco Angelone, Francesco Ciardelli, Arturo Colligiani*, Francesco Greco, Paolo Masi, Annalisa Romano, Giacomo Ruggeri, Jean Louis Stehlé

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


The photorefractivity of an indole derivative and of its polymer blends has been studied at room temperature. The indole derivative 3-[2-(4-nitrophenyl) ethenyl]-l-(2-ethymexyl)-2-methylindole (NPEMI-E) is a typical low-molecular-weight glass-forming molecule having peculiar nonlinear optics characteristics. It is unconditionally soluble in the photoconductive poly-(N-vinyl-2,3-dimethylindole) so that all the possible blends can be studied for a weight percent (wt. %) content of NPEMI-E ranging from zero to 100. A very high and sharp maximum of the photorefractive optical gain Γ2 ≈ 2000cm-1 was obtained for a NPEMI-E wt. % content of about 90. On the basis of recently published theoretical calculations, we have made the hypothesis that the rapid change of Γ2 can also be ascribed to a correspondingly quick variation of the molecular electro-optic parameters of the dissolved chromophore for some well distinguished values of its concentration in the polymer matrix. Differential scanning calorimetry measurements were made and the results carefully analyzed with the aim of obtaining information on the intermolecular interactions. These last measurements also allowed rationalizing the unconditionally stable glass appearance of the obtained blends. Measurements of spectroscopic ellipsometry were also made on blends with different NPEMI-E content.

Original languageEnglish
Pages (from-to)6680-6691
Number of pages12
JournalApplied Optics
Issue number36
Publication statusPublished - 2008 Dec 20
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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