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Economical Buffer Layer Boosts Performance of Organic Solar Cells
New compositions of matter have been invented, specifically organic buffer layer materials that can greatly enhance power conversion efficiency (PCE) of organic photovoltaic (OPV) devices and can effectively functionalize metal electrodes. Conventional-architecture OPV devices made using the new buffer layer have average PCEs greater than 8%, with the highest PCE value exceeding 9.5%. This new buffer layer can be used with Ag, Cu, and Au cathodes, opening routes to all-solution-based device fabrication and roll-to-roll processing. In addition, the new buffer layer materials can be applied at a layer thickness of up to 55 nm, avoiding processing challenges that occur with ultrathin buffer layers and enabling a simplified and reproducible process for device fabrication.
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A Simple, Robust Route for Generating Unidirectionally Aligned, Nanoscopic Line Patterns of Block Copolymers over Arbitrarily Large Areas
Researchers at UMass Amherst, UC Berkeley and Ulsan National Institute of Science and Technology have collaboratively developed a simple, robust route for producing unidirectionally aligned, nanoscopic line patterns of block copolymers over arbitrarily large areas, with an order parameter in excess of 0.97. The fabrication process combines the “bottom-up,” directed self-assembly of block copolymer approach to generation of nanoscopic surface structures with a unique strategy to guide perfect assembly of horizontally positioned nanocylindrical domains of block copolymers on non-defect-free substrates. In addition, the fabrication process does not require photolithography, e-beam lithography, or other processes employing a “top-down” patterning approach. The exceptional alignment is attainable either on reconstructed, faceted single crystal surfaces or on their replicas made with flexible, inexpensive polymeric materials. The block copolymer line patterns with perfect structural order over arbitrarily large areas can be used in subsequent roll-to-roll type pattern transfer and patterning processes and to serve as templates and scaffolds for the manufacture of a variety of addressable media and devices.
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