Superior Thermoelectric Performance of Black Phosphorus in Elemental Tellurium

Abstract Simple elemental thermoelectrics are an ideal platform to demonstrate fundamental physics in materials and develop new strategies for high‐efficiency energy conversion devices. Recently, black phosphorus (BP) is theoretically predicted as a superior thermoelectric candidate, however it meets a great challenge in practical application because of its poor stability. Here, it is reported that the BP phase can be stabilized from 300 to 610 K through creation of a heterojunction structure in Te‐based thermoelectrics, leading to simultaneously enhanced electrical behaviors and reduced thermal conductivity. The peak and average z T values at a temperature range of 300–610 K are increased by 49% and 30% in (Sb, Se, Ge)Te‐BP system, respectively. Maximum z T up to 1.1 at 610 K has been achieved, as the highest value in elemental Te‐based thermoelectrics throughout the measured temperature region. This study clarifies the multiple benefits of engineering a heterojunction structure in independently modulating the coupled parameters, and opens up a pathway searching high performance thermoelectric materials in BP‐based structures.