1 Introduction Modern aircraft and other vehicles often rely on carbon-fiber composites for their high strength-to- weight ratio and ability to be formed into a variety of shapes. However, many of the crucial functionali- ties in aircraft (e.g. communications, power, etc.) are implemented using bulky and failure-prone compo- nents carrying a weight penalty. With increasing emphasis on system-wide energy efficiency and weight reduction, there is an opportunity to create novel architectures of devices and composites that combine energy harvesting, energy storage, commu- nications and load-bearing capabilities into a single composite. Likewise, new methods are needed to fabricate such devices cost-effectively. Here we de- scribe new fiber-based architectures for solar cells, thermal energy conversion devices, and antennas that potentially facilitate integration with structural composites. Additionally, this talk will describe re- cent advances in the fabrication of energy conver- sion devices at ambient conditions. 2 Fiber-based device architectures 2.1 Organic solar cells on fibers To date, thin-film solid-state organic solar cells have been demonstrated by some laboratories to exceed 9% power conversion efficiency at 1 Sun illumina- tion. While this efficiency does not exceed that of the best inorganic-based solar cells, the basic device construction (i.e. 100-200 nm thick organic layers sandwiched between <100 nm thick electrodes) po- tentially lends itself to integration with substrates which possess load-bearing properties (e.g. glass- or carbon-fiber). In our laboratory, we have used ther- mal evaporation to deposit small-molecular organic solar cells onto a variety of substrates, including glass fibers. [1,2] Briefly, initial proof-of-principle OPV cells on fibers consisted of archetypal organic heterojunc- tions sandwiched between two electrodes, one of Fig. 1: (a) An illustration of vacuum thermal evaporation (VTE), in which source materials are deposited onto a substrate under vacuum. In one of our deposition systems, the fiber was rotated about its axis to produce a concentric coating. (b) A schematic of the in vacuo fiber rotation stage allowing deposition of multi-layer thin-film optoelectronic devices onto fibers. (c) A schematic of the photovoltaic (PV) cell layer structure deposited concentrically around a fiber, showing 7 layers and 6 separate materials that must be deposited onto a fiber pre-coated with a polyimide film. Note that this device does not use indium tin oxide (ITO) - a uniquitously utilized anode material that is sub-optimal for flexible and low-cost device applications due to cost and brittleness. 18 TH INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS NOVEL DEVICE ARCHITECTURES FOR ENABLING ENERGY HARVESTING, LIGHTING, AND COMMUNICATIONS FUNC- TIONALITIES IN COMPOSITES M. Shtein 1 *, B. O’Connor 2 , A. Yadav, 2 K. Pipe 2 , S.E. Morris, 3 Y. Bayram, 4 J. Volakis, 4 S. Biswas, 1 K. Luck, 1 M. Hendryx 1 1 Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA 2 Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA 3 Chemical Engineering, University of Michigan, Ann Arbor, MI, USA 4 Electrosciences Laboratory, Ohio State University, Columbus, OH, USA * Corresponding author (mshtein@umich.edu ) Keywords: fiber, solar cell, thermoelectric, woven antenna, deposition