Formation of Oriented Nanostructures from Single Molecules of Conjugated Polymers in Microdroplets of Solution:  The Role of Solvent

Abstract

We examine the role of solution-phase polymer geometries on the favorability of forming oriented nanostructures from single conjugated polymer molecules formed from microdroplets of ultradilute solution. To our knowledge, this is the first time single molecule fluorescence correlation spectroscopy has been used to extract structural information from solution-phase fluorescence measurements. We find that production of oriented species is strongly favored in “poorer” solvents, where the polymer chains have more compact solution-phase structures. While charging during droplet generation is essential for orientation, we conclude that most of the internal organization associated with these interesting structures takes place in solution, independent of the droplets.

Solvent-induced photoemissions of high-energy chromophores of conjugated Polymer MEH-PPV: Role of conformational disorder

“…The partially collapse of polymeric chains is indicated by the shift of absorption and emission spectra to relatively high energy region, which is consistent with the results from dynamic light scattering 15,16 and computer simulation. 17,18 The λ max of absorption and emission spectra are detected at 490 and 554 nm, respectively. We observe the same concentration effect on the emission of high-energy chromophores.…”

“…[8][9][10][11] In addition, the conjugated backbone can fold or twist introducing physical defects when chain length exceeds the persistence length. [12][13][14][15][16][17][18][19] The existence of the chemical and physical defects is an important factor that dictates the photophysics of conjugated polymers. The delocalization of π electrons or conjugation length is known to be confined between these defects.…”

“…19 One can control the averaged value of conjugation length, which in turn affects its emission behaviors, by tuning amount of the defects along conjugated backbone. This can be achieved by adjusting chain conformation [15][16][17][18][20][21][22] or incorporating a controllable quantity of chemical defects. 9,10 Chemical modification of the polymeric architectures is also an effective method for tuning the optical properties.…”

“…[15][16][17][18] In this study, we perform systematic experiments to explore the relationship between conformational change of MEH-PPV in dichloromethane, chloroform, tetrahydrofuran and the photoemissions of various chromophores. The magnitude of chain collapse in THF is lesser than our previous studies, implying larger separation between chromophores in single chain.…”

Stacking of oligo- and polythiophene cations in solution: Surface tension and dielectric saturation

“…The orientation and alignment of polymers in a solid matrix, the formation of aggregates in films and solution, or the ability of organic semiconductors to selfassemble, are the outcome of a complex balance between the spatial features of the molecules and the substrate and the interactions between them at the conditions of synthesis. [1][2][3][4][5][6][7][8][9] By dictating rules for aggregation, these interactions eventually shape properties such as charge delocalization and mobility 2,[9][10][11] or optical 3,[12][13][14] and electromechanical 15 responses. Thiophene-derived oligomers and polymers represent today one of the most promising class of organic semiconductors, finding potential applications in a variety of electronic and electroactive devices.…”