Cornell Center For Materials Research Research Articles

Model Membrane-Free Li-S Batteries for Enhanced Performance and Cycle Life.

The success of the rechargeable Li-S cell is limited in part by the dissolution of lithium-polysulfide in the electrolyte. Remarkably, it is found that removal of the conventional membrane separator in a Li-S cell improves sulfur utilization and cycling performance, whether the sulfur is initially contained in the cathode or electrolyte. An optimized cell design yields discharge capacities as high as 980 mA h g-1 after 100 cycles.

Ionic‐Liquid‐Tethered Nanoparticles: Hybrid Electrolytes

This work was supported by Award No. KUS-C1-018-02, made by King Abdullah University of Science and Technology (KAUST). Facilities available through the Cornell Center for Materials Research (CCMR), a Materials Research Science and Engineering Center of the National Science Foundation (DMR-0079992) were used for this study.

Designed Synthesis of Coaxial SnO2@carbon Hollow Nanospheres for Highly Reversible Lithium Storage

This publication was based on work supported by Award No. KUS-C1-018-02, made by King Abdullah University of Science and Technology (KAUST). We are also grateful to the National Science Foundation (DMR 0404278) for partial support. Facilities available through the Cornell Center for Materials Research (CCMR), and Cornell Integrated Microscopy Center (CIMC) were used for this study. Supporting Information is available online from Wiley InterScience or from the author. This article has been amended for print publication.

Evolution of the Women in Materials Program: a Collaboration between Simmons College and the Cornell Center for Materials Research

AbstractThe Women in Materials (WIM) program is an on-going collaboration between Simmons College and the Cornell Center for Materials Research (CCMR). Beginning in 2001, during the initial four years of the project, materials-related curricula were developed, a new joint research project was begun, and nearly 1/2 of Simmons College science majors participated in materials-related research during their first two years as undergraduates. We have previously reported the student outcomes as a result of this initial stage of the project, demonstrating a successful partnership between a primarily undergraduate women's college and a federally funded Materials Research Science and Engineering Center. Here, we report the evolution and impact of this project over the last three years, subsequent to the initial seed funding from the National Science Foundation. The Women in Materials project is now a key feature of the undergraduate science program at Simmons College and has developed into an organizing structure for materials-related research at the College. Initially, three faculty members were involved and now eight faculty members from all three laboratory science departments participate (biology, chemistry, and physics). The program now involves research related to optoelectronics, polymer synthesis, biomaterials, and green chemistry, and each semester about 80% of the students who participate in these projects are 1st and 2nd year science majors. This structure has led to enhanced funding within the sciences, shared instrumentation facilities, a new minor in materials science, and a spirit of collaboration among science faculty and departments. It has also spawned a new, innovative curricular initiative, the Undergraduate Laboratory Renaissance, now in its second year of implementation, involving all three laboratory science departments in incorporating actual, on-going research projects into introductory and intermediate science laboratories. Most importantly, the Women in Materials program has embedded materials-related research into our science curriculum and has deepened and broadened the educational experience for our students; the student outcomes speak to the program's success. Approximately 70% of our science majors go on to graduate school within two years of completing their undergraduate degree. Our students also have a high acceptance rate at highly competitive summer research programs, such as Research Experience for Undergraduates (REU) programs funded by the National Science Foundation.

Melissa Hines, director, Cornell Center for Materials Research, Ithaca, New York

Melissa Hines, director, Cornell Center for Materials Research, Ithaca, New York

Women in Materials: a Collaborative Effort between Simmons College and the Cornell Center for Materials Research

AbstractThe Women in Materials (WIM) program, supported by the National Science Foundation, is a collaboration between Simmons College, a predominately undergraduate women’s college, and the Cornell Center for Materials Research (CCMR). For the past four years, this program has provided unusual curricular and research opportunities for undergraduate women at Simmons College. This program demonstrates a successful model for enhancing undergraduate science and technology preparation through collaboration between primarily undergraduate institutions (PUIs) and NSF-supported Materials Research Science and Engineering Centers.

PUI/MRSEC Collaboration to Create Opportunities for Women in Materials-Research

ABSTRACTThis three-year collaboration between a predominately undergraduate women's college (Simmons College) and a NSF-supported Materials Research Science and Engineering Center (the Cornell Center for Materials Research (CCMR)) focuses on establishing a collaborative Simmons/Cornell research program that provides opportunities for students to work with faculty on timely research projects, have access to sophisticated instrumentation, and gain related work experience in industrial settings. To interest women in participating in materials-related research and to encourage them to consider further career exploration in this area, the secondary goal of the project focuses on augmenting women's undergraduate experience. In this regard, the project uses the PUI/MRSEC collaboration to enhance the undergraduate curriculum at Simmons and encourage new Ph.D.s in materials-related disciplines at Cornell to consider academic careers at Primarily Undergraduate Institutions (PUIs).To provide opportunities for students to work on research throughout their undergraduate careers, this program focuses on studying the degradation processes in organic light emitting diodes (OLEDs). These materials are currently of great interest for display applications, and an understanding and control of the degradation processes could ultimately influence their use in various types of consumer products.To widen science students' exposure to materials science, a new minor in materials was developed and materials science topics are being incorporated into physics and chemistry courses. To encourage students to consider graduate or industrial careers in materials science and to ease the transition into these large research environments, CCMR will place students in summer industrial jobs and REU positions. To provide students with further access to sophisticated instrumentation, a portion of the laboratory requirement for the new minor in materials will be co-taught during the summer by Simmons and Cornell collaborators at CCMR's Shared Experimental Facilities. Cornell's graduate students will participate in the program as mentors for Simmons undergraduates and will visit Simmons to better understand postgraduate teaching careers at PUIs.

Current-Induced Degradation in Polythiophene

ABSTRACTThe three-year collaboration between Simmons College and the Cornell Center for Materials Research (CCMR) is focused on undergraduate student/faculty research in organic light emitting diodes (OLEDs). The physics of OLED devices is characterized by three major processes: charge injection, charge transfer, and light emission as a result of the electron-hole recombination. In the first year of the program our research has been related to the first two stages.OLEDs based on small molecule as well as polymeric layers have been investigated. The devices were prepared using mostly aluminum (also nickel and iron) as electrodes and PC:TPD or polythiophene as the organic layer. Electrodes of about 20 nm were formed by vacuum evaporation, and organic layers of approximately 100–200 nm were spin-coated. The current-voltage characteristics, measured under forward and reverse bias up to 10 volts, demonstrate typical semiconductor S-shape behavior, and show variations dependent on aging, thickness of the polymer layer, and type and combination of electrodes.The results presented here specifically track the degradation of devices using polythiophene sandwiched between aluminum electrodes. The I-V curves and successive current response as a function of time and under constant voltage drive are presented along with complementary mass spectra and UV-visible and infrared absorption spectra. These measurements along with preliminary computer modeling of HOMO and LUMO energies for a series of thiophene oligomers suggest a correlation between internal changes in the polymer and variations in the electrical characteristics of the devices.

Steric Turnoff of Vibrationally Mediated Negative Differential Resistance in a Single Molecule.

Negative differential resistance (NDR), mediated by vibrational excitation, is strongly dependent on molecular structure and dynamics, according to scanning tunneling microscopy on Cu(001)-bound pyrrolidine and N-methylpyrrolidine at 9 K. Tunneling electrons cause the former to switch between conformations I and II, so that NDR is observed. The methyl group of of the latter compound restricts it to a single conformation, and a linear current-voltage characteristic results.