Bismuth telluride, Bi2Te3 and its alloys with Sb2Te3 and Bi2Se3are the most important class of thermoelectric materialsbecause they have the highest known efficiency near roomtemperature despite numerous attempts to discover bettermaterials. Being the best material, virtually every Peltier cooler made for efficient thermoelectric coolingor temperature management uses Bi2Te3alloys. Such solid-state devices dominatethe market for temperature control inoptoelectronics. As the need to eliminategreenhouse-gas refrigerants increases,Peltier cooling is becoming more attractive particularly in small systems whereefficiencies are comparable to traditionalrefrigerant based cooling. Such smalldevices may enable distributive heating/cooling (only where and when it is needed)with higher system level energy efficiency,for example in electric vehicles whereenergy for heating/cooling competes withvehicle range. Even for thermoelectricpower generation, e.g., recovery of wasteheat, Bi2Te3 alloys are most used becauseof superior efficiency up to 200 °C and thetechnology to make devices with Bi2Te3 ismost advanced.[1–3]