Presentation on theme: "CHESS DMR-0936384 2013 L. A. Perez, K. W. Chou, J. A. Love, T. S. van der Poll, D.-M. Smilgies, T.-Q. Nguyen, E. J. Kramer, A. Amassian and G. C. Bazan,"— Presentation transcript:
CHESS DMR L. A. Perez, K. W. Chou, J. A. Love, T. S. van der Poll, D.-M. Smilgies, T.-Q. Nguyen, E. J. Kramer, A. Amassian and G. C. Bazan, Solvent Additive Effects on Small Molecule Crystallization in Bulk Heterojunction Solar Cells Probed During Spin Casting, Advanced Materials 25(44), (2013). Intellectual Merit: Solvent additive processing is a pre- electrode deposition technique that has been implemented in many high performance and record-breaking solution- processable conjugated polymer-fullerene bulk heterojunction (BHJ) solar cell devices. Here, the Santa Barbara group reports the first demonstration of structural evolution of thin films during spin casting, with and without solvent additive processing. The study used in situ grazing incidence wide angle X-ray scattering (GIWAXS) with sub- second time resolution to demonstrate that the addition of small amounts of additives to primary solutions can promote and accelerate the rate at which a thermodynamically stable polymorphs can form. The additive invokes three effects: the formation of a metastable polymorph, kinetically favors its transformation into a more stable polymorph, and increases the degree of crystallinity and the crystallite correlation length at the onset of film formation during the spin-casting process. These measurements provide experimental evidence of the crystallization kinetics of spun-cast solution processable small molecule based BHJ films and of complex structural evolution during casting owing to solvent additive processing. Bulk Heterojunction Solar Cells Probed During Spin Casting Joel Brock, Cornell University, DMR In situ GIWAXS image plots during spin- casting (a) and (b) during metastable phase formation and drying.
CHESS DMR L. A. Perez, K. W. Chou, J. A. Love, T. S. van der Poll, D.-M. Smilgies, T.-Q. Nguyen, E. J. Kramer, A. Amassian and G. C. Bazan, Solvent Additive Effects on Small Molecule Crystallization in Bulk Heterojunction Solar Cells Probed During Spin Casting, Advanced Materials 25(44), (2013). Broader Impacts: Solvent additive processing is a pre- electrode deposition technique that has been implemented in many high performance and record-breaking solution- processable conjugated polymer-fullerene bulk heterojunction solar cell devices. This solution processing technique adds a small volume, ≈ 1–6%, of a high-boiling-point liquid to the casting solution. This small addition improves several key solar cell device metrics, in certain cases significantly increasing the power conversion efficiency. Unlike solvent or thermal annealing, solvent additive processing doesn’t require an extra processing step for device optimization. The Santa Barbara group used CHESS’s x-ray facilities to probe the crystallization kinetics of chemical blends during film casting and drying, with and without solvent additive processing. These studies provide critical insight into the crystallization sequence by showing when the additive effect occurs during film evolution. These results will aid in determining the mechanism by which additives modify the structure and will assist future studies of technologically candidate organic solar cell systems Bulk Heterojunction Solar Cells Probed During Spin Casting Joel Brock, Cornell University, DMR
CHESS DMR Ada Yonath gave the 2013 Efraim Racker Lecture in Biology and Medicine, “Life Expectancy”, on Nov. 14 in Call Auditorium, Kennedy Hall, Cornell University. For previous articles on her work at CHESS: Community Outreach: Ada Yonath is a professor of structural biology at Israel's Weizmann Institute of Science and co-recipient of the 2009 Nobel Prize in chemistry "for studies of the structure and function of the ribosome", along with Thomas Steitz of Yale University and Venkatraman Ramakrishnan of Cambridge. Starting in the mid-1980s, Ada Yonath was a frequent CHESS user, utilizing the newly constructed F1 station designed especially for macromolecular crystallography. Her extensive work on well-diffracting ribosome crystals, developing new approaches to mounting and cryocooling the samples, ultimately led to high- resolution structural models. Based on these models, new antibiotics, blocking the functioning of bacterial ribosomes, can be developed. Nobel laureate talks life expectancy, antibiotics Joel Brock, Cornell University, DMR
CHESS DMR In situ measurements reveal new insights into packed bundles of carbon nanotubes. The pixel- array-detector (PAD) indicated at right provides very fast framing capabilities for capturing structural evolution on the microsecond timeframe. See also: And: E.R. Meshot, E.A. Verploegen, M. Bedewy, S. Tawfick, A.R. Woll, K.S. Green, M. Hromalik, L.J. Koerner, H.T. Philipp, M.W. Tate, S.M. Gruner, and A.J. Hart; "High-speed in situ X-ray Scattering of Carbon Nanotube Film Nucleation and Self-organization", ACS Nano. 6: (2012). Intellectual Merit: A new endstation capability for performing in situ growth of carbon nanotube systems while characterizing them with x-ray scattering is now available to CHESS users. Two user groups have used the custom-built glass-tube furnace (Absolute Nano, Plymouth, MI) at G1 for in situ studies of thermal behavior in thin films. The furnace is based on a design originally brought to G1 by John Hart’s group (MIT, then at University of Michigan) to study fabrication and kinetic effects in carbon nano-tube forests. The furnace uses highly doped, single-crystal silicon as the sample stage and heater. The temperature response is fast (~100C/second), accurate, and results in relatively little sample motion from thermal expansion. The furnace can be operated in air or under gas flow, and exchanging samples is straightforward and fast. GISAXS/GIWAXS Furnace Ready For Action Joel Brock, Cornell University, DMR
CHESS DMR Photo of the in situ x-ray scattering furnace. E.R. Meshot, E.A. Verploegen, M. Bedewy, S. Tawfick, A.R. Woll, K.S. Green, M. Hromalik, L.J. Koerner, H.T. Philipp, M.W. Tate, S.M. Gruner, and A.J. Hart; "High-speed in situ X- ray Scattering of Carbon Nanotube Film Nucleation and Self- organization", ACS Nano. 6: (2012). Broader Impacts: This furnace brings a new end station capability to the CHESS user community. CHESS staff have worked with graduate students from two research groups, one based at Cornell and another at Princeton, to commission and fine-tune the instrument. Upon delivery, initial assembly and tests were performed by graduate students Joerg Werner and Hiroaki Sai (PhD, 2012) in Ulrich Weisner's group at Cornell. Next, CHESS post-doc Robin Baur interfaced the RS-232 temperature control interface to the SPEC control software. Finally, Anna Hispanski, a graduate student in Lynn Loo's group (Chemical and Biological Engineering, Princeton) worked with CHESS scientist Arthur Woll to characterize and optimize the temperature measurement, response and control of the system. As of November 2013, the system was running well. The furnace is ready for general use. Interested users should contact Arthur Woll or Kathy Dedrick. GISAXS/GIWAXS Furnace Ready For Action Joel Brock, Cornell University, DMR
CHESS DMR Post-doctoral associate Matthew Ward, designer of the glovebox facility at CHESS. Specimens enter the box using the portals at left; the interior environment is oxygen and moisture free down to parts per million. New Specimen Prep Capability: CHESS has added an MBraun Labmaster glovebox to its suite of sample preparation facilities. The new glovebox provides users with an air and moisture free environment to store and prepare air sensitive samples for measurement at CHESS. Currently the glovebox provides a dry nitrogen environment; however, future upgrades will allow users to select nitrogen, argon, or helium environments dependent upon experimental needs. During the fall x- ray running period the glovebox was installed and commissioned MBraun and tested by two local Cornell experimental groups. The Abruña Group, from the Department of Chemistry, used the glovebox facility to load a custom battery cell for real time diffraction experiments during battery cycling. The Robinson Group, from the Department of Materials Science and Engineering, used the glovebox to initiate a chemical transformation reaction for real time wide angle x-ray scattering measurements during the chemical transformation. The glovebox will be available to all CHESS users in New Oxygen-Free, Environmental Glovebox Facility Joel Brock, Cornell University, DMR Ward, CHESS