I lead a project focused on measurements to accelerate the development of organic films and devices for flexible circuits, displays, and solar cells. We apply a suite of techniques to reveal the micro- and nano-scale structure features that control performance, including polarized spectroscopies (IR, vis, and X-ray), ellipsometry and reflectivity, wide and small angle scattering, and electron and scanning probe microscopy. (link: Organic Electronics and Photovoltaics Project)
My work includes a specialization in Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy, which is a powerful synchrotron-based tool that measures the composition and orientation of organic systems. (link: NIST NEXAFS capabilities)
I also specialize in electrochemical measurements and devices, including self assembled systems for energy storage and displays.
Honors and Awards
- Presidential Early Career Award for Scientists and Engineers (PECASE) (2009)
- NIST Bronze Medal Award (2008)
- Sigma Xi young Investigator Award (2008
- NRC/NIST Postdoctoral Fellow Appointment (2003)
- NSF/KOSEF Korea Summer Institute Award (2002)
- MRS Graduate Student Award (2002)
- National Defense Science and Engineering Graduate Fellowship Appointment (1998)
National Research Council Postdoctoral Fellowship – Open to U.S. citizens with an annual stipend of $63,400 per year (as of 2009). link: NRC video
Polymer Semiconductor Film Structure
We determined the detailed film structure in pBTTTs, a series of thiophene ring semiconductors with alkyl side chains and record-setting charge mobilities. We determined the substrate-relative tilts of the pBTTT conjugated plane, side chains, and backbones using our suite of spectroscopies. By combining orientation information with crystal spacings from X-ray diffraction and microscopy, we could discern important structure details. Notably, the conjugated planes have a preferred tilt, and the side chains are highly interdigitated.
Advanced Materials, 2007, 19, (6), 833-837. (link)
Polymer Semiconductor Phase Transitions
We determined the mechanism of performance enhancement in the thermal annealing of pBTTTs. The layer structure dramatically improved when the film entered a mesophase at ≈ 140°C. Polarized IR revealed that the molecular mechanism of performance enhancement was the melting of alkane side chains. Once the side chains melt, the backbones move to eliminate packing defects in a smectic-like liquid crystalline state. Upon cooling, the side chains recrystallize. Side chain interdigitation therefore provides a general mechanism to achieve and then preserve layer order, because it allows "repairs" to defective crystals and then “locks in” the order.
Macromolecules, 2008, 41, (15), 5709-5715. (link)
Oriented Polymer Semiconductors
Oriented domains of pBTTT are created with a flow-coating technique, where films are cast by mechanically spreading a solution with slow and directional drying. Cast films initially exhibit little in-plane orientation, but orientation increases dramatically after films are heated to a liquid-like state and then cooled. The oriented domains appear as terraced ribbons with a terrace height of 2.1 nm and a ribbon width equivalent to the length of a fully extended pBTTT chain. The ribbon interiors have high levels of molecular order and surface-relative orientation.
ACS Nano, 2009, 3, (4), 780-787. (link)
- DS Germack, CK Chan, BH Hamadani, LJ Richter, DA Fischer, DJ Gundlach, DM DeLongchamp, "Substrate-dependent interface composition and charge transport in films for organic photovoltaics." Applied Physics Letters, 2009, 94, 233303. (link)
- DM DeLongchamp, RJ Kline, Y Jung, DS Germack, EK Lin, AJ Moad, LJ Richter, MF Toney, M Heeney, L McCulloch, "Controlling the Orientation of Terraced Nanoscale "Ribbons" of a Poly(thiophene) Semiconductor." ACS Nano, 2009, 3, (4), 780-787. (link)
- CE Mauldin, K Puntambekar, AR Murphy, F Laio, JMJ Fréchet, V Subramanian, DM DeLongchamp, DA Fischer, MF Toney, "Solution Processible alpha, omega-Distyryl Oligothiophene Semiconductors with Enhanced Environmental Stability." Chemistry of Materials, 2009, (ASAP). (link)
- DM DeLongchamp, RJ Kline, Y Jung, EK Lin, DA Fischer, DJ Gundlach, SK Cotts, AJ Moad, LJ Richter, MF Toney, M Heeney, I McCulloch, "Molecular Basis of Mesophase Ordering in a Thiophene-Based Copolymer." Macromolecules, 2008, 41, (15), 5709-5715. (link)
- I McCulloch, M Heeney, M Chabinyc, DM DeLongchamp, JR Kline, M Cölle, W Duffy, DA Fischer, DJ Gundlach, B Hamadani, R Hamilton, LJ Richter, A Salleo, M Shkunov, D Sparrowe, S Tierney, W Zhang, "Semiconducting Thienothiophene Copolymers: Design, Synthesis, Morphology and Performance in Thin Film Organic Transistors." Advanced Materials, 2008, in press. (link)
- BM Vogel, DM DeLongchamp, CM Mahoney, LA Lucas, DA Fischer, EK Lin, "Interfacial modification of silica surfaces through gamma-isocyanatopropyl triethoxy silane-amine coupling reactions." Applied Surface Science, 2008, 254, (6), 1789-1796. (link)
- O Esenturk, RJ Kline, DM Delongchamp, EJ Heilweil, "Conjugation Effects on Carrier Mobilities of Polythiophenes Probed by Time-Resolved Terahertz Spectroscopy." Journal of Physical Chemistry C, 2008, 112, (29), 10587-10590. (link)
- J Park, RQ Yang, CV Hoven, A Garcia, DA Fischer, TQ Nguyen, GC Bazan, DM DeLongchamp, "Structural characterization of conjugated polyelectrolyte electron transport layers by NEXAFS spectroscopy." Advanced Materials, 2008, 20, (13), 2491. (link)
- Y Quan, SCB Mannsfeld, ML Tang, M Roberts, MF Toney, DM DeLongchamp, Z Bao, "Microstructure of oligofluorene asymmetric derivatives in organic thin film transistors." Chemistry of Materials, 2008, 20, (8), 2763-2772. (link)
- Y Jung, RJ Kline, EK Lin, DA Fischer, MF Toney, M Heeney, I McCulloch, DM DeLongchamp, "The Impact of the Dielectric/Semiconductor Interface on Microstructure and Charge Carrier Transport in High-Performance Polythiophene Transistors." Electrochemical Society Transactions, 2008, 13, (2), 113-122.
- LA Lucas, DM DeLongchamp, LJ Richter, RJ Kline, DA Fischer, BR Kaafarani, GE Jabbour, "Thin Film Microstructure of a Solution Processable Pyrene-Based Organic Semiconductor." Chemistry of Materials, 2008, 20, (18), 5743-5749. (link)
- Y Jung, RJ Kline, DA Fischer, EK Lin, M Heeney, I McCulloch, DM DeLongchamp, "The Effect of Interfacial Roughness on the Thin Film Morphology and Charge Transport of High-Performance Polythiophenes." Advanced Materials, 2008, 18, (5), 742-750. (link)
- RJ Kline, DM DeLongchamp, DA Fischer, EK Lin, LJ Richter, ML Chabinyc, MF Toney, M Heeney, I McCulloch, "Critical role of side-chain attachment density on the order and device performance of polythiophenes." Macromolecules, 2007, 40, (22), 7960-7965. (link)
- DM DeLongchamp, RJ Kline, EK Lin, DA Fischer, LJ Richter, LA Lucas, M Heeney, I McCulloch, JE Northrup, "High carrier mobility polythiophene thin films: Structure determination by experiment and theory." Advanced Materials, 2007, 19, (6), 833-837. (link)
- TH Epps, DM DeLongchamp, MJ Fasolka, DA Fischer, EL Jablonski, "Substrate surface energy dependent morphology and dewetting in an ABC triblock copolymer film." Langmuir, 2007, 23, (6), 3355-3362. (link)
- NS Zacharia, DM DeLongchamp, M Modestino, PT Hammond, "Controlling diffusion and exchange in layer-by-layer assemblies." Macromolecules, 2007, 40, (5), 1598-1603. (link)
- DM DeLongchamp, EK Lin, DA Fischer, "Near Edge X-ray Absorption Fine Structure (NEXAFS) Spectroscopy." In Organic Field-Effect Transistors, Bao, Z.; Locklin, J., Eds. CRC Press: New York, 2007; pp 277-300.
- RJ Kline, DM DeLongchamp, DA Fischer, EK Lin, M Heeney, I McCulloch, MF Toney, "Significant dependence of morphology and charge carrier mobility on substrate surface chemistry in high performance polythiophene semiconductor films." Applied Physics Letters, 2007, 90, (6). (link)
- MC Gurau, DM Delongchamp, BM Vogel, EK Lin, DA Fischer, S Sambasivan, LJ Richter, "Measuring Molecular Order in Poly(3 alkylthiophene) Thin Films with Polarizing Spectroscopies." Langmuir, 2007, 23, (2), 834 -842. (link)
- LA Lucas, DM DeLongchamp, BM Vogel, EK Lin, MJ Fasolka, DA Fischer, I McCulloch, M Heeney, GE Jabbour, "Combinatorial screening of the effect of temperature on the microstructure and mobility of a high performance polythiophene semiconductor." Applied Physics Letters 2007, 90, (1). (link)<
- DM DeLongchamp, MM Ling, Y Jung, DA Fischer, ME Roberts, EK Lin, ZN Bao, "Thickness dependence of microstructure in semiconducting films of an oligofluorene derivative." Journal of the American Chemical Society, 2006, 128, (51), 16579-16586. (link)
- C Xu, SE Barnes, T Wu, DA Fischer, DM DeLongchamp, JD Batteas, KL Beers, "Solution and surface composition gradients via microfluidic confinement: Fabrication of a statistical-copolymer-brush composition gradient." Advanced Materials, 2006, 18, (11), 1427. (link)
- ML Chabinyc, F Endicott, BD Vogt, DM DeLongchamp, EK Lin, YL Wu, P Liu, BS Ong, "Effects of humidity on unencapsulated poly(thiophene) thin-film transistors." Applied Physics Letters 2006, 88, (11), 3. (link)
- DM DeLongchamp, YS Jung, DA Fischer, EK Lin, P Chang, V Subramanian, AR Murphy, JMJ Frechet, "Correlating molecular design to microstructure in thermally convertible oligothiophenes: The effect of branched versus linear end groups." Journal of Physical Chemistry B, 2006, 110, (22), 10645-10650. (link)
- DM DeLongchamp, BM Vogel, Y Jung, MC Gurau, CA Richter, OA Kirillov, J Obrzut, DA Fischer, S Sambasivan, LJ Richter, EK Lin, "Variations in semiconducting polymer microstructure and hole mobility with spin-coating speed." Chemistry Of Materials, 2005, 17, (23), 5610-5612. (link)
- DM DeLongchamp, S Sambasivan, DA Fischer, EK Lin, P Chang, AR Murphy, JMJ Frechet, V Subramanian, "Direct correlation of organic semiconductor film structure to field-effect mobility." Advanced Materials, 2005, 17, (19), 2340-+. (link)
- AR Murphy, PC Chang, P VanDyke, JS Liu, JMJ Frechet, V Subramanian, DM DeLongchamp, S Sambasivan, DA Fischer, EK Lin, "Self-assembly, molecular ordering, and charge mobility in solution-processed ultrathin oligothiophene films." Chemistry Of Materials, 2005, 17, (24), 6033-6041. (link)
- DM DeLongchamp, EK Lin, DA Fischer, "Organic semiconductor structure and chemistry from near-edge X-ray absorption fine structure (NEXAFS) spectroscopy." Proceedings of the SPIE, 2005, 5940, 54-64.
- BD Vogt, HJ Lee, VM Prabhu, DM DeLongchamp, EK Lin, WL Wu, SK Satija, "X-ray and neutron reflectivity measurements of moisture transport through model multilayered barrier films for flexible displays." Journal of Applied Physics, 2005, 97, (11). (link)
- DM DeLongchamp, BD Vogt, CM Brooks, K Kano, J Obrzut, CA Richter, OA Kirillov, EK Lin, "Influence of a water rinse on the structure and properties of poly(3,4-ethylene dioxythiophene): poly(styrene sulfonate) films." Langmuir, 2005, 21, (24), 11480-11483. (link)
- DM DeLongchamp, PT Hammond, "Electrochromic polyaniline films from layer-by-layer assembly." In Chromogenic Phenomena in Polymers, 2005; Vol. 888, pp 18-33.
- DM DeLongchamp, PT Hammond, "High-contrast electrochromism and controllable dissolution of assembled Prussian blue/polymer nanocomposites." Advanced Functional Materials, 2004, 14, (3), 224-232. (link)
- DM DeLongchamp, PT Hammond, "Highly ion conductive poly(ethylene oxide)-based solid polymer electrolytes from hydrogen bonding layer-by-layer assembly." Langmuir, 2004, 20, (13), 5403-5411. (link)
- DM DeLongchamp, PT Hammond, "Multiple-color electrochromism from layer-by-layer-assembled polyaniline/Prussian Blue nanocomposite thin films." Chemistry of Materials, 2004, 16, (23), 4799-4805. (link)
- DM DeLongchamp, M Kastantin, PT Hammond, "High-contrast electrochromism from layer-by-layer polymer films." Chemistry of Materials, 2003, 15, (8), 1575-1586. (link)
- DM DeLongchamp, PT Hammond, "Fast ion conduction in layer-by-layer polymer films." Chemistry of Materials, 2003, 15, (5), 1165-1173. (link)
- D DeLongchamp, PT Hammond, "Layer-by-layer assembly of PEDOT/polyaniline electrochromic devices." Advanced Materials, 2001, 13, (19), 1455-+. (link)
Project Leader: Organic Electronics and Photovoltaics
Electronics Materials Group
- Ph.D., MIT Chemical Engineering, 2003.
Advisor: Paula T. Hammond
(link: Paula's Group)
- M.S.C.E.P. MIT Chemical Engineering, 2000.
(link: Practice School)
- B.S. Georgia Tech Chemical Engineering, 1998.