Irvine-Halliday (pictured here with some sample hardware, new and old) realized that then-new white-light LED's could offer a solution - a bright, efficient light source that could be run from simple batteries, which in turn could be recharged by a small array of solar cells. Such simple LED lamps can provide enough light after dark to read, prepare meals, and even engage in small home-based businesses (crafts, making clothing, performing repairs, etc.). He founded the Light Up The World foundation to promote the development and distribution of such lighting. As it says on the LUTW web site:
Light Up The World Foundation (LUTW) is the first humanitarian organization to utilize renewable energy and solid-state lighting technologies to bring affordable, safe, healthy, efficient, and environmentally responsible illumination to people who do not have access to power for adequate lighting. LUTW remains the world’s leader in this endeavour: globally active and setting standards in the field.LUTW is raising money for this effort, but they are also encouraging the use of microcredit loans to allow people to buy the necessary hardware with small payments that would otherwise go to buying kerosene for lamps. This also creates opportunities for local small businesses. They can assemble and sell lamps, batteries, and solar cells and even make money recycling batteries.
This is a great application of optics, solid-state physics, solar photovoltaics, and other advanced technologies to solve a simple problem in a simple way, with immediate and local benefits. It's a great idea and a great cause to support. For more information, you can explore the LUTW web site, or read this technical paper (PDF) from SPIE.