Complex electronic structure and compositing effect in high performance thermoelectric BiCuSeO

Abstract

BiCuSeO oxyselenides are promising thermoelectric materials, yet further thermoelectric figure of merit ZT improvement is largely limited by the inferior electrical transport properties. The established literature on these materials shows only one power factor maximum upon carrier concentration optimization, which is typical for most thermoelectric semiconductors. Surprisingly, we found three power factor maxima when doping Bi with Pb. Based on our first-principles calculations, numerical modeling, and experimental investigation, we attribute the three maxima to the Fermi energy optimization, band convergence, and compositing effect due to in situ formed PbSe precipitates. Consequently, three ZT peaks of 0.9, 1.1, and 1.3 at 873 K are achieved for 4, 10, and 14 at.% Pb-doped samples, respectively, revealing the significance of complex electronic structure and multiple roles of Pb in BiCuSeO. The results establish an accurate band structure characterization for BiCuSeO and identify the role of band convergence and nanoprecipitation as the driving mechanism for high ZT.

High ZT 2D Thermoelectrics by Design: Strong Interlayer Vibration and Complete Band‐Extrema Alignment

“…Thermoelectric (TE) conversion technology, through directly converting waste heat into electricity, [ 1–4 ] has drawn strong interest in the energy science sector. To keep pace with the demand of continuous miniaturization of thermoelectric devices, recently much attention has been devoted to the development of 2D high‐efficiency TE materials with controllable thickness.…”

Prediction of higher thermoelectric performance in BiOCuSe by weakening electron-polar optical phonon scattering

“…8,9 BiOCuSe-based materials have emerged as state-of-the-art thermoelectric oxychalcogenides since 2010. 9,10 Various doping strategies, such as substitution of Bi with alkali, 11,12 alkaline earth, 9,[13][14][15][16] and post-transition metals such as lead, [17][18][19][20] have been successfully demonstrated to obtain ZT values close or beyond unity at high temperatures. The highest p-type ZT have reached 1.5 at 873 K by employing a dual-doping method at the Bi site in Bi 0.88 Ca 0.06 Pb 0.06 OCuSe.…”

“…21 However, the low carrier mobility of BiOCuSe (~ 20 cm 2 V -1 s -1 at room temperature vs. 525 cm 2 V -1 s -1 of Bi 2 Te 3 at 300 K) limits further optimization of the thermoelectric performance. 1,20,22 Computational analysis that applies deformation potential (DP) theory has been used to explain the charge transport properties of BiOCuSe by assuming that longitudinal acoustic (LA) phonons dominates charge transport, [23][24][25] which is based on the fact that the measured mobility obeys the temperature power law of T -1.5 . 15 This power law assumes the existence of a single parabolic band (SPB).…”

“…4 . The assumption made until now when investigating mobility in BiOCuSe that LA phonon scattering follows a power law of ~ T -1.5 , 15,20,24 is therefore incorrect. This can be attributed to the multivalley valence bands of BiOCuSe, as occurs for InTe, where LA phonon scattering coupled with intervalley scattering results in a power law of T -2.01 .…”

The structural, electronic, elastic and high thermoelectric properties of a new Zintl compound Ba<sub>3</sub>Sn<sub>3</sub>Sb<sub>4</sub> studiedby first principles

“…材料较低的热电转换效率并不能满 足实际应用需求, 因此, 研究者采用多种措施提高材料 的热电特性. 有的研究人员将Pb [8] 和Li [9] 替换Bi位 [10] 或 La和Pb共掺在Bi位 [10] , BiCuSeO的ZT值有了很大提升;…”