| AVS 66th International Symposium & Exhibition | |
| Thin Films Division | Wednesday Sessions |
| Session TF1-WeM |
| Session: | Vapor Deposition of Functional Polymer Thin Films and Composites |
| Presenter: | Spencer Ferguson, Duke University |
| Authors: | S. Ferguson, Duke University B. Zhang, Duke University A.D. Stiff-Roberts, Duke University |
| Correspondent: | Click to Email |
An important goal for functional polymer thin film deposition is to selectively deposit semi-crystalline phases to enable unique properties. As a specific example, semi-crystalline β-polyfluorene (β-PFO) could improve the performance of blue polymer light emitting diodes (LEDs) due to better color purity and enhanced charge conduction. However, it has been challenging to directly investigate the impact of this crystalline phase on the performance of PFO-based LEDs films deposited by spin-casting due to poor surface quality with prominent pinholes resulting from the poor solvents or additives used to promote β-PFO[1,2]. Previous work[3] has shown that emulsion-based, resonant infrared matrix-assisted pulsed laser evaporation (RIR- MAPLE) enables deposition of pinhole-free thin films containing β-PFO.
In order to further study the ability of the emulsion target used in RIR-MAPLE to promote the deposition of β-PFO, the emulsion surfactant will be investigated to study the impact of the polarity difference between the primary PFO solvent (trichlorobenzene) and the water within the emulsion. The standard surfactant used in RIR-MAPLE is sodium dodecyl sulfate, and it has a single hydrophobic tail. In a reported study on PFO, phospholipids were used to form a lamellar structure within an emulsion to drop cast films with high concentrations of β-PFO[4]. In contrast to SDS, the phospholipid surfactant has multiple hydrophobic tails, which could significantly impact the formation of β-PFO by RIR-MAPLE. In addition, sodium alkyl aryl sulfonate will be investigated as a surfactant to determine the impact of aromatic rings on the promotion of β-PFO. As a second study, the annealing of deposited films below the glass transition temperature of PFO will be investigated to determine the impact on β-PFO concentration and the overall film morphology.
For each study, UV-Vis absorbance, photoluminescence, and surface morphology will be characterized. This work will provide a path to the fabrication of thin films containing greater concentrations of β-PFO for inclusion as the active region in blue polymer LEDs.
This material is based upon work supported by the National Science Foundation under Grant No. NSF CMMI-1727572.
1. J. Peet, E. Brocker, Y. Xu, and G. C. Bazan, Adv. Mater. 20, 1882 (2008).
2. B. Liu, T. Li, H. Zhang, T. Ma, J. Ren, B. Liu, J. Lin, M. Yu, L. Xie, and D. Lu, J. Phys. Chem. C 122, 14814 (2018).
3. S. Ferguson, C. V. Williams, B. Mohapi, and A. D. Stiff-Roberts, J. Electron. Mater. 48, 3388 (2019).
4. M. J. Tapia, M. Monteserín, H. D. Burrows, J. S. Seixas De Melo, J. Pina, R. A. E. Castro, S. García, and J. Estelrich, J. Phys. Chem. B 115, 5794 (2011).