Oxide-based thermoelectric materials that show a high figure of merit are promising because of their good chemical and thermal stabilities and their relative harmlessness compared with chalcogenide-based state-of-the-art thermoelectric materials. Although several high-ZT thermoelectric oxides (ZT > 1) have been reported thus far, their reliability levels are low due to the lack of careful observations of their stabilities at elevated temperatures. Herein, we review the epitaxial film growth and thermoelectric properties of representative p-type layered cobalt oxides: Na_3/4CoO₂, Ca_1/3CoO₂, Sr_1/3CoO₂, Ba_1/3CoO₂, and Ca₃Co₄O₉. Among these specimens, Ba_1/3CoO₂ and Ca₃Co₄O₉ are stable in air at elevated temperatures (~600 °C). The ZT of Ba_1/3CoO₂ reaches ~ 0.55 at 600 °C in air, which is reliable and the highest among thermoelectric oxides. Moreover, this value is comparable to those of p-type PbTe and p-type SiGe.

与硫族化物基最先进的热电材料相比，氧化物基热电材料具有良好的化学稳定性和热稳定性，并且相对无害，因此具有高品质因数，因此前景广阔。尽管迄今为止已经报道了几种高ZT热电氧化物（ZT  >1），但由于缺乏对其在高温下的稳定性的仔细观察，它们的可靠性水平较低。在此，我们回顾了代表性p型层状钴氧化物的外延薄膜生长和热电性能：Na _3/4 CoO ₂、Ca _1/3 CoO ₂、Sr _1/3 CoO ₂、Ba _1/3 CoO ₂和Ca ₃ Co ₄ O ₉。在这些样品中，Ba _1/3 CoO ₂和Ca ₃ Co ₄ O ₉在高温（~600 °C）的空气中是稳定的。Ba _1/3 CoO _{2在空气中600} ℃时的ZT达到~0.55，这是可靠的并且是热电氧化物中最高的。而且，该值与p型PbTe和p型SiGe的值相当。