Chromophore Orientation Dynamics, Phase Stability, and Photorefractive Effects in Branched Azobenzene Chromophores

Abstract

The increased solubility and uniform dispersal of branched azobenzene chromophores over their monomeric analogues have been shown to improve the electrooptic performance of high glass transition temperature (T g ) blended polymers. We report here the application of these branched chromophores as guest nonlinear optical molecules in the plasticized low-T g photoconducting host polymer poly(vinylcarbazole) and demonstrate the presence of orientationally enhanced photorefractive index gratings. When compared with their monomeric analogues, branched chromophores were compatible over a broader range of concentrations and resulted in higher quality optical films; these films have retained their optical clarity for 1 year. A new branched electrooptic chromophore with r 33 of 14 pm/V at 1550 nm was synthesized and exhibited photorefractive two-beam coupling over a range of applied fields, including a net two-beam coupling amplification coefficient of 6.4 cm -1 at 780 nm.

Organic Photorefractive Materials and Applications

“…[ 179 ] Nevertheless, it is observed empirically , [ 13 ] that the maximum content of chromophore that can be incorporated into a material scales with the alkyl content. Similarly, branched chromophores [ 181 ] and aromatic substitution of aliphatic endgroups [ 171 ] were discussed to increase the shelf lifetime of the materials. It should be pointed out, that substitutions on the NLO molecule may adversely affect the orientational mobility of the chromophore under applied fi elds.…”

“…Furthermore, these issues tend to aggravate in light of the higher polarity of optimized ( μ 2 δ a) chromophores with regard to traditional ( μβ ) chromophores (see Table 4 ). [ 170 ] 45 DMNPAA, [ 62 ] 46 DMNPAPOE, [ 171 ] 47 DMNPAPBE, [ 171 ] 48 DMNPAPhBUE, [ 171 ] 49 7-DCST, [ 46 ] 50 PDCST, [ 29,46 ] 51 AODCST, [ 46 ] 52 DEANST, [ 115 ] 53 F-DEANST, [ 82,162 ] 54 DB-IP-DC, [172,173] 55 NPEMI-A, [ 174 ] 56 NPEMI-E, [ 174 , 175 ] 57 H1, [ 176 ] 58 H2, [ 176 ] 59 DANS, [ 168 , 165 ] 60 DBA-TCP, [ 177 ] 61 DBP-TCP, [ 177 ] 62 IDOP-20, [ 162 ] 63 ATOP-1, [162,166,178] 64 ATOP-4, [ 162,179 ] 65 DHADC-MPN, [86,180] 66 , [ 181 ] 67 .…”

“…66 , 67 ), [ 181 ] the use of mixtures of chromophores (e.g. the 1:1 wt.% eutectic mixture of DMNPAA and MNPAA, [ 170 ] or a 4:1 mixture of DBDC/7-DCST, [ 184 ] ) or incorporating chromophores of high structural similarity with the respective photoconducting host.…”

Azobenzene Polymers for Photonic Applications

“…Dendritic and branched molecular architectures can have better solubility properties and can be used to control undesired aggregation, resulting in higher quality films for optical applications (Campbell et al, 2006;Ma et al, 2002). Dendrimers with strongly absorbing pendants can act as antenna, harvesting light and making it available, via intramolecular energy transfer, to the dendrimer core.…”

Ar–ArF Self‐Assembly of Star‐Shaped Second‐Order Nonlinear Optical Chromophores Achieving Large Macroscopic Nonlinearities

“…[5,[9][10][11] In the past two decades, a wide variety of dendritic NLO materials with very promising macroscopic NLO effects have www.advelectronicmat.de their low synthetic complexity but high NLO activities. [16,18,[28][29][30][31][32][33][34] Thus, to further explore the advantages of this structure, in this communication, three simple, multibranched NLO materials T1-T3 (Figure 1) were prepared using triphenylamine as the core to link pentafluorobenzene groups modified azobenzenebased chromophores. In T1-T3, the number of chromophore arms attached to the core was changed from one to three with an attempt in studying the effect of this adjusted molecular structure on the bulky structure and consequent macroscopic NLO effects.…”