This career proposal focuses on the research and education in the development of organic spintronics based on spin injection and modification of spin-orbital coupling in magnetic organic light-emitting diodes (OLEDs). The goal of this career project is to develop a novel approach to control the excited state processes and charge transport in organic semiconductor devices by using magnetic field.
Intellectual Merit: The integrated research will address two critical challenges: spin-polarized charge injection and modification of spin-orbital coupling in magnetic OLEDs by using nano-dot ferromagnetic electrodes and soluble organic materials mixing. Spin-polarized charge injection and modification of spin-orbital coupling will be used to control magnetic field-dependent charge transport and spin-dependent exciton dynamic processes. The investigations will focus on three critically important fundamental issues: spin transport across nanoscale ferromagnetic/organic heterojunction, spin-orbital-coupling dependent magnetoresistance, and cooperative interaction of spin injection-generated excitons based on magnetic organic OLEDs for the development of organic spintronics.
Broader Impact: The proposed career project has two broader impacts on research and education. The research impact includes the development of new approach to control excited state processes and charge transport by using both spin injection from nano-dot ferromagnetic electrodes and modification of spin-orbital coupling from organic materials mixing. The proposed studies will increase the critical understanding of spin transport and spin-dependent excitonic processes in organic semiconductor devices. The new understanding will largely contribute to the development of magnetic organic light-emitting, magnetic lasing, and magnetic photovoltaic devices in the applications of national defense and energy technologies. The educational impact includes the curriculum development, student mentoring, minority and women involvement, and outreach activities to high school students in the education of engineering disciplines with concentration in magnetic organic semiconductor devices through using the PI's experience and project-specific interaction with existing College of Engineering diversity and outreach programs at the University of Tennessee.
has produced two significant outcomes in intellectual merit and broader impact. In intellectual merit, this project has established a new strategy to solve challenging problem in organic spintronics by combining the concept of nanomaterails with magnetic properties. Furthermore, this project has also developed a unique methodology to magnetically control electronic, optic, and optoelectronic properties in organic semiconductors by using intermolecular excited states. In broader impact, this project has made two particular impacts. First, the project has largely enhanced education by developing new courses for graduate and undergraduate students. Second, this project has involved a large number of high-school students, undergraduate students, female graduate students, and minority graduate students in the research. During the project period, this project has prepared 5 Ph.D students and 2 master students. The specific outcomes include: Spin injection: we discovered an effective method to efficiently inject spin-polarized carriers into organic semiconductors by using nanoscale ferromagnetic/organic heterojunctions [Phys. Review B, 75, 075213 (2007)]. Magnetic field effects on charge transport: We discovered a significant mechanism to tune magnetoresistance between positive and negative values by adjusting exciton dissociation and exciton-charge reaction [Nature Materials, 6, 985 (2007)]. Magnetic field effects on excited states: We discovered a new mechanism to generate magnetic field effects on photoluminescence and electroluminescence by using intermolecular excited states in non-magnetic organic semiconductors [Adv. Mater. 21, 1500, 2009]. Tuning spin-orbital coupling: We found an effective method to tune spin-orbital coupling in organic semiconductors by using intermolecular magnetic interactions between spin of delocalized p electron and orbital magnetic field of localized electron through materials mixing [Phys. Rev. B, 75, 035214 (2007)]. Hall effects based spintronics: We discovered a new mechanism to generate magnetic field effects by using Hall effect [Adv. Mater. 23, 2216-2220, 2011]. By using Hall effect, we demonstrated giant magnetic field effects on electroluminescence (> 500 %) in liquid states. Electric-magnetic coupling: We discovered a unique mechanism to couple electrical that delocalized p electrons and spin-polarized d electrons can be coupled in organic + magnetic nanocomposites through charge transfer in excited states to show both charge density and mobility based magnetoresistance simultaneously [J. Am. Chem. Soc. 134, 3549-3554, 2012].
