Superior Thermoelectric Performance of Black Phosphorus in Elemental Tellurium

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 zT values at a temperature range of 300-610 K are increased by 49% and 30% in (Sb, Se, Ge)Te-BP system, respectively. Maximum zT 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.