For decades, physicists have toyed with ways to convert heat into electricity directly. Materials known as thermoelectrics use temperature differences to drive electrons from one end to another. The displaced electrons create a voltage that can in turn be used to power other things, like a battery. But, existing technologies can turn only 5–7% of heat energy into electricity. So, building a better thermoelectric totally depends on finding materials that conduct electricity, but not heat. Recently, some scientists at Northwestern University have created a new material from lead telluride and believes that the material is able to convert waste heat to electricity.