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Research Areas

The Center for Interface Science: Solar-Electric Materials (CIS:SEM) is an Energy Frontier Research Center (EFRC) with The University of Arizona as the lead institution. CIS:SEM scientists and engineers are addressing the basic science issues underlying interfacial processes – at nanometer length scales – which currently limit the energy conversion efficiencies and scale-up of inexpensive solar-to-electric energy conversion technologies such as Generation III organic solar cells (OSCs). The focus on interface science and charge transfer across interfaces is the central feature of our effort, which will provide unique student training opportunities. The CIS:SEM team includes scientists and engineers from The University of Arizona, the Georgia Institute of Technology, Princeton University, the University of Washington, and the National Renewable Research Laboratory (NREL).

The need to understand interfacial charge injection and electron-transfer processes for OSCs and related thin-film photovoltaic systems is described in the U.S. DOE Report “Basic Research Needs for Solar Energy Utilization.” Low-cost, area-scalable, energy conversion technologies have multiple interfaces which limit efficiency and lifetime and for which a basic, nanometer-scale understanding is not available. CIS:SEM will develop predictive understandings of interfaces in OSCs: (i) between organic semiconductors and oxides; (ii) between two dissimilar organic semiconductors; and (iii) between organic semiconductors and metals. CIS:SEM scientists and engineers are addressing the basic science issues of interfaces in OSCs through the following Research Areas:

  1. Device Physics: Development of new theories to explain charge transfer between organic semiconductors and oxides, metals, and emerging nontraditional conductors.
  2. Surface Science/Theory: Using state-of-the-art characterization tools to explore interface composition, light absorption, charge formation and transport, and charge collection in OSCs, on time scales from femtoseconds to minutes, and length scales from nanometers to device-scale.
  3. Materials: Development of new nanostructured hybrid organic, metallic and oxide composite materials to precisely control composition near interfaces in nanometer-thick regions, leading to energy conversion devices with disruptively higher efficiency and lower cost.

For example, some of the key scientific questions to be addressed by CIS:SEM include:

  1. How is the rate of (heterogeneous) electron transfer across organic/oxide and organic/metal interfaces controlled by the composition and electronic properties of the contact materials?
  2. How does the heterogeneity of electrical properties in oxide and metal films, at sub-micron length scales, impact macroscopic device properties?
  3. How is electron transfer across an organic/oxide or an organic/metal interface influenced by the surface coverage, bonding, orientation, redox functionality and dipolar nature of surface modifiers?
  4. How is electron transfer across an organic/oxide or an organic/metal interface affected by nano-texturing of the interface?
  5. How can one predict the thermo-mechanical and electrical stability of interfaces from their chemical composition?