Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 13, Issue 29, Pages 34367-34373Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.1c08686
Keywords
thermoelectric; Cu2Se; electronic structure; molecular dynamics; phonon transport
Funding
- National Natural Science Foundation of China [91963207, 11774271]
- Suzhou Key Industrial Technology Innovation Project [SYG201921]
- Supercomputing Center of Wuhan University
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The high-temperature phase of Cu2Se, beta-Cu2Se, has attracted attention for its excellent thermoelectric efficiency. Studying the effect of strain and the possibility of n-type beta-Cu2Se is essential, with compressive strain promoting the power factor and tensile strain reducing lattice thermal conductivity. Predicted zT values for n-type and p-type beta-Cu2Se can reach 1.65 and 1.71 at 800 K respectively, and a feasible strategy to manipulate the lattice structure and carrier type is proposed through doping halogen elements.
In recent years, the high-temperature phase of Cu2Se, namely, beta-Cu2Se, has attracted increasing attention due to its outstanding thermoelectric efficiency. The Cu ions in beta-Cu2Se show a distinct ion-liquid behavior between the framework of a Se ion lattice. Many experimental operations may lead to a discrepancy in the lattice structure. Experimentally synthesized beta-Cu2Se was p-type, and a thermoelectric device needs both p-type and n-type materials with a close figure of merit. Studying the effect of strain and the possibility of n-type beta-Cu2Se is essential. Utilizing first-principles calculations and molecular dynamics simulations, we investigate the thermoelectric performance of strained beta-Cu2Se. The results show that the n-type beta-Cu2Se can exhibit superior zT values like the p-type one. Applying compressive strain is an effective way to promote the power factor. The tensile strain will lead to a low lattice thermal conductivity and thus boost the p-type zT values. The predicted maximum zT values for n-type and p-type beta-Cu2Se can reach 1.65 and 1.71 at 800 K, respectively. Considering the fact that applying strain is challenging in experiments, we propose a feasible strategy to manipulate the lattice structure and carrier type: doping halogen elements. Our results provide a guide for Cu2Se-based thermoelectric devices.
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