Nanosys said today it has raised $15 million in a sixth round of funding to expand its manufacturing of materials that enable displays with vivid colors. The Palo Alto, Calif.-based maker of nanotechnology materials — or materials that have unique properties at a scale of a billionth of a meter — will use the investment to expand its manufacturing capacity tenfold. The company makes Quantum Dot Enhancement Film (QDEF), which improves the vividness of color and power efficiency of liquid crystal displays, which are used in everything from tablets to big-screen TVs.