Thermoelectric optimization of AgBiSe2 by defect engineering for room-temperature applications

• DOI: 10.1103/physrevb.99.155203
• Publication Date: 2019-04-17T13:44:09Z
• Authors: Zhenzhen Feng; Xiaoli Zhang; Yuanxu Wang; Jihua Zhang; Tiantian Jia; Bingqiang Cao; Yongsheng Zhang
• Keywords: 01 natural sciences; 0104 chemical sciences

The hexagonal phase of $\mathrm{AgBiS}{\mathrm{e}}_{2}$ has been discovered as a promising thermoelectric material for room-temperature applications. However, its basic conduction type is still ambiguous, and current ZT value pretty low. To improve the performance $\mathrm{AgBiS}{\mathrm{e}}_{2}$, we apply band engineering to modify structure by introducing defects increase degeneracy. From calculated intrinsic point defect formation energies at different growth conditions, clarify that conducting behavior $p$-type semiconductor, Ag vacancy dominated acceptor. Based on scrutinizing two kinds methodologies can be used achieve high degeneracy: (i) shifting Fermi level into valence using defects, (ii) converging several valence-band maxima extrinsic defects. We find helpful significantly power factor, leading large vacancy-doped $\mathrm{AgBiS}{\mathrm{e}}_{2}$: maximum increased 0.3--0.5 near room temperature. analyzing bonding characters atomic energy levels in compound, predict dopants (Cu, Rh, Pd) converge three maxima. Our work provides applications tuning structures or