Understanding the role of polymer structures on electronic processes in polymer optoelectronic devices

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Light emitting polymers are making a major impact in the electronics industry by providing a new technology for low-cost, large-area devices. Provided that issues regarding efficiency, lifetime and durability are resolved, the next generation of polymer devices have the potential for an even greater impact as ultra-high efficiency devices for lighting applications, photovoltaic devices, and field effect transistors.The research proposed here is focussed on understanding the role of polymer structures on three important and related electronic processes that determine the performance and efficiency of polymer devices, with the ultimate aim of developing strategies to enhance the performance of these devices. The electronic processes to be investigated are (i) processes that determine the singlet exciton yield, and hence the electroluminescence quantum efficiency of light emitting devices; (ii) exciton transport in polymer films, which determines the efficiency of photovoltaic devices; and (iii) the role of long-lived interface states on electron-hole recombination and dissociation, which determines the efficiency of either light emitting or photovoltaic devices.These processes are affected by polymer structures on a variety of length scales, including the chemical structure of the polymers, local polymer conformations, the relative packing of polymers, and the global mesoscale morphology. Using a variety of computational techniques (including quantum chemistry calculations of electronic structure, quantum master equation simulations of charge and energy transport, and molecular dynamics simulations of polymer conformation and packing) the present proposal is focussed on understanding the roles of chemical structure, conformation and packing on the efficiency of these processes. This will provide strategies for enhancing the performance of polymer devices. It will also provide guidance as to how the efficiency of present devices compares to their theoretical optimal values.