This work has been accepted for publication in Advanced Functional Materials (2008 ISI Impact Factor: 6.808).
Electroluminescent polymers are attractive for developing all-organic light-emitting devices due to the potential advantages that polymeric systems may off er in the large-scale manufacturing of electronics. Nonetheless, many of these electroluminescent pi-conjugated polymers are inherently insoluble in the solvents employed in the intended solution-based manufacturing processes. One such polymer is poly(2,5- dioctyl-1,4-phenylenevinylene) (POPPV), where the inherent lack of solubility of POPPV in organic solvents has frustrated its widespread application in devices and no organic light emitting devices (OLED) have been presented that exploit its electroluminescence characteristics. In this e ort, a unique strategy is presented for the preparation of hybrid nanoparticle composed of POPPV, a green emitter (lambda_em = 505 nm), and poly(9,9-di-n-octyl uorenyl-2,7-diyl) (PFO), a blue emitter (lambda_em = 417 nm). The aqueous-based nanoparticle dispersion composed of these hybrid particles was stable to aggregation and employed in the construction of OLEDs. The color characteristics of the electroluminescence for the devices could be tuned by exploiting the Forster resonance energy transfer between the polymers within a particle, while suppressing energy transfer between particles. These aqueous-based nanoparticle dispersions are amenable to being printed into devices through high-throughput manufacturing techniques, for example, roll-to-roll printing.
foulger
The range of hole mobilities varied from 2.4x10−8cm2/Vs for copolymers containing 50 mol. % of the carbazole-containing monomer residue to 3.0x10−7cm2/Vs for copolymers which incorporated 88 mol. % of the residue. Density functional theory (B3LYP/6-31G*) and optical absorption derived HOMO & LUMO energies of the carbazole containing methacrylate monomer were -5.39 eV and -1.94 eV, respectively, while the corresponding oxadiazole monomer had a HOMO energy of -5.99 eV and a LUMO energy of -2.23 eV. Mean luminous efficiency of coumarin 6 doped single-layer devices constructed from the copolymers indicated a relatively flat efficiency of ca. 0.25 cd/A over a wide carbazole mole fraction content of 0.30 to 0.70.
The cover of the Journal of Materials Chemistry for October, 2008 depicts research in our group on electroluminescent colloidal particles.
These particles were synthesized and could be designed to produce a range of colors by mixing together various ratios of red-, green-, and blue-emitting particles and were utilized in colloidally-based organic light emitting devices. In addition, the colloids were converted into inks that were printed on a flexographic roll-to-roll printer. You can find more information about this research by visiting the story on this
A news item about our collaborative work with 
the Sonoco Institute on
Electroluminescent Colloidal Inks for Flexographic Roll-to-Roll Printing
is now available on the
The academic and commercial interest in organic light-emitting devices (OLEDs) is motivated in-part by the potential of building devices utilizing inexpensive polymers coupled with simple & inexpensive fabrication routes. For example, OLEDs have been developed that utilize an established electroluminescent (EL) dye embedded in a hole and an electron transporting polymer host. In this effort, we exploit methyl methacrylate derived monomers functionalized with pendant carbazole & oxadiazole moieties and copolymerized to form a charge-transporting random copolymer. The glass transition temperature of the copolymers could be predicted with a Fox equation and ranged from 140 °C to 191 °C. The photoluminescent characteristics of the copolymers, both in solution and in solid films, exhibited emission that was a combination of sharp and broad peaks, suggestive of monomeric and chromophore aggregation emission. These trends were also apparent in the electroluminescent response of the copolymers, where the appearance of an electromer emission was evident and was tentatively assigned to the carbazole moieties.
The academic and commercial interest in organic light-emitting devices (OLEDs) is motivated in-part by the potential of building devices utilizing simple & inexpensive fabrication routes, for example, commercial printing techniques. The focus on synthetically challenging small molecules and pi-conjugated polymers, or cost-prohibitive quantum dot (QD) systems, for these devices is countered by the alternative of developing emissive materials that utilize an established electroluminescent (EL) dye embedded in a hole and an electron transporting host. In this effort, we exploit readily obtainable materials and simple fabrication routes to produce light emitting colloidal particles, which in turn, allows us to invoke the concept of a “particle-device”. The major theme of this submission centers around the development of EL devices based on inexpensive & readily available materials that can be fabricated using high-throughput (e.g., hundreds of meters per second) commercial printing technologies. 
In our group, we have recently been exploring the direct patterning of intrinsically conductive polymer inks through various printing methods. In an earlier publication, we reported the roll-to-roll printing of polyaniline (PANI) coated poly(butyl methacrylate) (PBMA) core-shell particles 
Christopher F. Huebner, a PhD candidate in the Foulger Group, will present a talk and poster at the 4th Annual Excellence in Polymer Graduate Research Symposium for the 235th ACS National Meeting in New Orleans.
Individuals were nominated by their respective institutions to represent their university as the top graduate students in polymer chemistry/science.
Selection in this symposium, which is sponsored by the