Thermoelectric performance of(AgBiTe_(2))_(1-x)(SnTe)_(x) with stable cubic enabled by enhanced configurational entropy

ABX_(2)(A=Ag,Na,Cu;B=Sb,Bi;X=S,Se,Te)(GroupsⅠ-Ⅴ-Ⅵ_(2))compounds,which are all characterized by the ultralow lattice thermal conductivity because of their strong lattice anharmonicity caused by lone-pair electrons,have aroused wide attention in thermoelectric community.The practical application of thermoelectric devices usually requires both the compatible n-type and p-type materials simultaneously.However,most ofⅠ-Ⅴ-Ⅵ_(2)compounds are intrinsic p-type semiconductors,lacking their n-type counterparts for thermoelectrics.Herein,in this work,we increase the configuration entropy of AgBiTe_(2)by alloying SnTe,in order to stabilize the cubic phase at room temperature.With further optimization of thermal and electrical performance,the thermoelectric performance could be improved simultaneously in both n-and p-type(AgBiTe_(2))_(1-x)(SnTe)_(x)(x=0.3,0.4)solid solutions.Finally,p-type compound with the nominal composition of(AgBi_(0.99)Cd_(0.01)Te_(2))_(0.6)(SnTe)_(0.4)and n-type of(AgBiTe_(2))_(0.7)(SnTe)_(0.3)~Br 6%show the maximum zT of~0.33 and~0.21,at 381 and 423 K,respectively.

Enhanced thermoelectric performance of Cu_(2)SnSe_(3) via synergistic effects of Cd-doping and CuGaTe_(2) alloying

In this work,we show significantly enhanced thermoelectric performance in Cu_(2) SnSe_(3) via a synergistic effect of Cd-doping and CuGaTe_(2) alloying in the temperature range of 300-823 K.Both the electron and phonon transport properties can be simultaneously regulated by Cd doping at Sn site,leading to a higher quality factor.Meanwhile,a maximum figure of merit(zT) value of ~0.68 was obtained for Cu_(2) Sn_(0.93)Cd_(0.07)Se_(3) sample at823 K,which is about four times higher than that of the pristine sample(zT=0.18 at 773 K).Furthermore,Cu_(2) Sn_(0.93)Cd_(0.07)Se_(3) was alloyed with CuGaTe_(2) to reduce the lattice thermal conductivity in the high-temperature region.Consequently,a further enhanced zT value(0.77,823 K) was achieved in the(Cu_(2) Sn_(0.93)Cd_(0.07)Se_(3))_(0.94)(CuGaTe_(2))_(0.06) sample,with a high average zT(zT_(ave)) value of0.30 between 300 and 823 K.These results demonstrate that Cd-doping combined with CuGaTe2 alloying could be an effective method to enhance zT values of Cu_(2) SnSe_(3) based compounds.