Aromatic molecules are a robust and versatile platform for the development of functional materials for electronic and optical applications. Using a tandem organic synthesis / device analysis approach, we seek to determine structure-property relationships that lead to materials with exceptional performance in organic thin-film transistors (for flexible flat-panel displays), organic solar cells (for low-cost generation of electricity) and organic light-emitting diodes (for high-efficiency lighting). Needless to say, students in my group learn a wide range of skills, from organic synthesis to materials characterization and device fabrication.
We are also exploring new functionalization strategies to further enhance the stability of these strongly-absorbing molecules, for use in low-cost solar cells.
Materials: In collaboration with the UK X-ray crystallography facility, we have developed an excellent model that allows us to predict the solid-state order of acenes functionalized by our method - the fine-tuning allows us to make subtle changes that improve film morphology, electrode contacts or photostability. Following this model, we have prepared materials with record-high performance in a number of areas.
Transistors: A field-effect transistor is a three-electrode device that turns current between two of the electrodes (labeled "source" and "drain") off or on by application of voltage across the third electrode (called the "gate"). For use in organic transistors, we have obtained the best results using molecules that exhibit two-dimensional pi-stacking in the sold state. We collaborate with many physics and engineering research groups to discover the device performance of the materials we prepare. For example, collaboration with the Loo group has shown new methods to control the crystal size in anthradithiophene materials, while the Jurchescu group has used spray-coating to form large-area transistor arrays with mobility as high as 5 cm2/Vs.
Solar cells: Acenes can also be used as the donor or acceptor material in organic solar cells. Using acene donors, we've seen power conversion efficiencies > 1% from traditional spin-cast solar cells, and nearly that much from solar cells spray-painted on arbitrary surfaces. The acene acceptors work even better - blends of polythiophene with cyanopentacenes leads to power conversion efficiency over 1.5%.
I am grateful to all of my collaborators (many of whom are not mentioned on this short web page) for their insight, assistance, and for being such fantastic people to work with. I also thank the support (both intellectual and financial) of our research programs by the Office of Naval Research, the National Science Foundation, and the King Abdullah University of Science and Technology.
B. Purushothaman, S. R. Parkin, J. E. Anthony "Synthesis and stability of soluble hexacenes" Org. Lett. 12, 2060 – 2063 (2010).
E. G. Bittle, J. W. Brill, J. E. Anthony "Electro-optic measurement of carrier mobility in an organic thin-film transistor" Appl. Phys. Lett. 97, 013302 (2010).
J. Smith, A. Bashir, G. Adamopoulos, J. E. Anthony, D. D. C. Bradley, M. Heeney, I. McCulloch, T. D. Anthopoulos "Air-stable solution-processed hybrid transistors with hole and electron mobilities exceeding 2 cm2 V-1 s-1" Adv. Mater. 22, 3598 – 3602 (2010).
J. R. Kline, S. D. Hudson, X.-R. Zhang, D. J. Gundlach, A. J. Moad, O. D. Jurchescu, T. N. Jackson, S. Subramanian, J. E. Anthony, M. F. Toney "Controlling the microstructure of solution-processable small molecules in thin film transistors through substrate chemistry" Chem. Mater. 23, 1194 – 1203 (2011)
Z. Li, Y.-F. Lim, J. B. Kim, S. R. Parkin, Y.-L. Loo, G. G. Malliaras, J. E. Anthony "Isomerically pure electron-deficient anthradithiophenes and their acceptor performance in polymer solar cells" Chem. Commun. 47, 7617 – 7619 (2011)
B. Purushothaman, M. Bruzek, S. R. Parkin, A.-F. Miller, J. E. Anthony "Synthesis and structural characterization of crystalline nonacenes" Angew. Chem. Int. Ed. 50, 7013 – 7017 (2011)
J. E. Anthony "Small-molecule, non-fullerene acceptors for polymer solar cells", invited review, Chem. Mater. 23, 583 – 590 (2011)
Y. Shu, Y.-F. Lim, Z. Li, B. Purushothaman, R. Hallani, J. E. Kim, S. R. Parkin, G. G. Malliaras, J. E. Anthony “A survey of electron-deficient pentacenes as acceptors in polymer bulk-heterojunction solar cells” Chemical Sciences 2, 363 – 366 (2011)
K. P. Goetz, Z. Li, J. W. Ward, C. Bougher, J. Rivnay, J. Smith, B. R. Conrad, S. R. Parkin, T. D. Anthopoulos, A. Salleo, J. E. Anthony, O. D. Jurchescu "Effect of acene length on electronic properties in 5-, 6-, and 7-ringed heteroacenes" Adv. Mater. 23, 3698 – 3703 (2011)
. S. S. Lee, M. A. Loth, J. E. Anthony, Y.-L. Loo "Orientation-independent charge transport in single spherulites from solution-processed organic semiconductors" J. Am. Chem. Soc. 134, 5436 – 5439 (2012)
B. Purushothaman, S. R. Parkin, M. J. Kendrick, D. David, J. W. Ward, L. Yu, N. Stingelin, O. D. Jurchescu, O. Ostroverkhova, J. E. Anthony "Synthesis and charge transport studies of stable, soluble hexacenes" Chem. Commun. 48, 8261 – 8263 (2012)
O. L. Griffith, J. E. Anthony, A. G. Jones, Y. Shu, D. L. Lichtenberger "Substituent Effects on the Electronic Characteristics of Pentacene Derivatives for Organic Electronic Devices: Dioxolane-Substituted Pentacene Derivatives with Triisopropylsilylethynyl Functional Groups", J. Am. Chem. Soc. 134, 14185 - 14194 (2012)
R. Li, U. Hadayat, M. M. Payne, D.-M. Smilgies, J. E. Anthony, A. Amassian “Heterogeneous nucleation promotes carrier transport in solution-processed organic field-effect transistors” Adv. Funct. Mater. 23, 291 - 297 (2013)
H. T. Yi, M. M. Payne, J. E. Anthony, V. Podzorov "Ultra flexible solution processed organic field-effect transistors" Nature Communications. 3, 1259 – 1262 (2012)
H. U. Khan, R. P. Li, Y. Ren, L. Chen, M. M. Payne, U. S. Bhansali, D. M. Smilgies, J. E. Anthony, A. Amassian “Solvent vapor annealing in the molecular regime drastically improves carrier transport in small-molecule thin-film transistors” ACS Appl. Mater. & Interface 5, 2325 – 2330 (2013)
J. Lee, M. J. Bruzek, N. J. Thompson, M. Y. Sfeir, J. E. Anthony, M. A. Baldo “Singlet exciton fission in a hexacene derivative” Adv. Mater. 25, 1445 – 1448 (2013)