Optimizing carrier mobility with composition and processing is key for thermoelectric coolers Thermoelectric technology enables direct and reversible conversion between thermal and electrical energies, which includes waste heat recovery and solid-state cooling ( 1 ). Compared with power generation, because of the Peltier effect, thermoelectric cooling has application advantages in precise temperature control, fast response, and size controllability. Because it is mainly used around ambient temperature with a small temperature difference, the issue of device failure under large temperature differences is no longer a problem ( 2 ). In addition to use in civil and industrial areas, thermoelectric cooling has an important role for precise temperature control in key areas such as 5G communications and electronic devices. The development of highly integrated and miniaturized communication technologies and circuit systems and the urgent demand for lower power dissipations have put forward higher requirements for the development of thermoelectric cooling.