The quest for thermoelectric materials that efficiently convert changes in temperature into electric voltage is challenging. For optimal performance, a material must conduct small amounts of heat and large amounts of electricity. However, crystal structure and electrons that carry electricity also carry heat. Researchers have identified black phosphorus (BP) as a candidate for novel applications. Doping BP with arsenic results in a two-dimensional (2D) material with a structure that may break the link between heat and electrical conductivity. In 2D layered materials, electrons are very mobile within the layers. However, weak chemical bonding between layers limits the transmission of heat between planes. This means the structure selectively reduces the transmission of heat, resulting in better performance.