Nanowires promise to make LEDs more colorful and solar cells more efficient, in addition to speeding up computers. That is, provided that the tiny semiconductors convert electric energy into light, and vice versa, at the right wavelengths. Researchers have managed to produce nanowires with operating wavelengths that can be freely selected over a wide range. Fine-tuned nanowires could take on several roles in optoelectronic components, thus making them more powerful, more cost-effective, and easier to integrate.