High-performance and low thermal conductivity in nano-layered Cu<sub>2</sub>Se prepared by a NaCl-flux method

Liu, Wenting; Shen, Lanxian; Shai, Xuxia; Sun, Luqi; Lü, Jianguo; Chen, Jiali; Ge, Wen; Deng, Shukang

doi:10.1039/c9ce01258c

Cited by 10 publications

(6 citation statements)

References 42 publications

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“…In recent years, various strategies have been proposed to enhance the ZT values of materials, such as band engineering, − nanostructure engineering, nano-composite structures, − secondary-phase incorporation, − and the “phonon-glass electron-crystal” (PGEC) paradigm . Among these approaches, the PGEC is a very effective and popular approach to enhance TE properties of materials, which could reduce the lattice thermal conductivity by enhancing phonon scattering without sacrificing electronic transport properties.…”

Section: Introductionmentioning

confidence: 99%

Synergetic Optimization of Electrical and Thermal Transport Properties by Cu Vacancies and Nanopores in Cu₂Se

Zhao

Ning

et al. 2021

ACS Appl. Mater. Interfaces

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In this study, a series of Cu2+x–y In y Se (−0.3 ≤ x ≤ 0.2 and 0 ≤ y ≤ 0.05) samples were prepared by melting and the spark plasma sintering method. X-ray diffraction measurements indicate that the Cu-deficient samples (x = −0.3 y = 0 and x = −0.2 y = 0) prefer to form the cubic phase (β-Cu2Se). Adding excessive Cu or introducing In atoms into the Cu2Se matrix triggers a phase transition from the β to α phase. Positron lifetime measurements confirm the reduction in Cu vacancy concentration by adding excessive Cu or introducing In atoms into Cu2Se, which causes a dramatic decrease in carrier concentration from 1.59 × 1021 to 5.0 × 1019 cm–3 at room temperature. The samples with In contents of 0.01 and 0.03 show a high power factor of about 1 mW m–1 K–2 at room temperature due to the optimization of the carrier concentration. Meanwhile, the excess Cu content and doping of In atoms also favor the formation of nanopores. These pores have strong interaction with phonons, leading to remarkable reduction in lattice thermal conductivity. Finally, a high ZT value of about 1.44 is achieved at 873 K in the Cu1.99In0.01Se (x = 0 and y = 0.01) sample, which is about twice that of the Cu-deficient sample (Cu1.7Se). Our work provides a viable insight into tuning vacancy defects to improve efficiently the electrical and thermal transport performance for copper-based thermoelectric materials.

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Section: Introductionmentioning

confidence: 99%

Synergetic Optimization of Electrical and Thermal Transport Properties by Cu Vacancies and Nanopores in Cu₂Se

Zhao

Ning

et al. 2021

ACS Appl. Mater. Interfaces

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“…The intrinsic thermoelectric properties of materials are sensitive to lattice strain. , It is necessary to study the lattice strain effect on the thermoelectric properties of β-Cu 2 Se individually. In addition, it has been noticed that Cu 2 Se tends to form Cu vacancies during synthesis and exhibits to be p-type, , which arose the question that why is it hard to synthesize n-type β-Cu 2 Se and what is the thermoelectric performance of n-type β-Cu 2 Se. To address these issues, theoretical methods have been taken to investigate the thermoelectric properties of strained β-Cu 2 Se.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric Properties of Strained β-Cu₂Se

Cao

Wang

Liu

et al. 2021

ACS Appl. Mater. Interfaces

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In recent years, the high-temperature phase of Cu 2 Se, namely, β-Cu 2 Se, has attracted increasing attention due to its outstanding thermoelectric efficiency. The Cu ions in β-Cu 2 Se 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 β-Cu 2 Se 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 β-Cu 2 Se is essential. Utilizing first-principles calculations and molecular dynamics simulations, we investigate the thermoelectric performance of strained β-Cu 2 Se. The results show that the n-type β-Cu 2 Se 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 β-Cu 2 Se 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 Cu 2 Se-based thermoelectric devices.

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“…Among the state-of-the-art excellent thermoelectric materials, Cu 2 Se has been widely studied due to its high performance and environmentally friendly nature compared to lead-based thermoelectric materials, in addition to its lower cost than tellurides. [4][5][6][7][8][9][10] It is discovered that Cu 2 Se shows extraordinary "liquid like" behavior of copper ions and reaches a ZT of 1.5 at 1000 K, among the highest value for bulk material. [4] Furthermore, there is a striking feature that Cu 2 Se has an abnormal transport behavior in the temperature range between 340 and 400 K, where a phase transition from the low-temperature 𝛼-Cu 2 Se phase to the hightemperature 𝛽-Cu 2 Se phase takes place, which has attracted extensive attention.…”

Section: Introductionmentioning

confidence: 99%

A Self‐Independent Binary‐Sublattice Construction in Cu₂Se Thermoelectric Materials

Zhao

et al. 2023

Adv Funct Materials

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The atomic‐scale structure of cuprous selenide room temperature phase (α‐Cu2Se), which plays an important role in understanding the mechanism of its high thermoelectric performance, is still not fully determined. Here, direct observation with atomic‐scale resolution is realized to reveal the fine structure of α‐Cu2Se via spherical‐aberration‐corrected scanning transmission electron microscopy. It is observed to be an interesting self‐independent binary‐sublattice construction for Cu and Se in α‐Cu2Se, respectively, which shows a variety of ordered copper fluctuation structures are embedded in a rigid pseudo‐cubic Se sublattice. Ordering of Cu uses a variety of configurations with little energy difference, forming considerable amounts of “boundaries,” which may lead to ultrastrong phonon scattering. Furthermore, density functional theory calculations indicate that the electronic structures are mainly determined by the rigid Se face‐centered cubic sublattice and not sensitive to the various copper fluctuations, which may guarantee the electron transfers with large carrier mobility. The self‐independent binary‐sublattice construction is speculated to enhance phonon scattering while still maintaining good electrical transport property. This study provides new critical information for further understanding the possible correlation between the specific structure and thermoelectric performance of α‐Cu2Se, as well as designing new thermoelectric materials.

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High-performance and low thermal conductivity in nano-layered Cu₂Se prepared by a NaCl-flux method

Abstract: In this study, a nano-layered Cu2Se high-performance material is successfully grown using a NaCl-flux method based on the stoichiometric ratios of Cu2Se(NaCl)x (x = 1.5, 2, 2.5, 3, and 3.5).

Cited by 10 publications

References 42 publications

Synergetic Optimization of Electrical and Thermal Transport Properties by Cu Vacancies and Nanopores in Cu₂Se

Synergetic Optimization of Electrical and Thermal Transport Properties by Cu Vacancies and Nanopores in Cu₂Se

Thermoelectric Properties of Strained β-Cu₂Se

A Self‐Independent Binary‐Sublattice Construction in Cu₂Se Thermoelectric Materials

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High-performance and low thermal conductivity in nano-layered Cu2Se prepared by a NaCl-flux method

Abstract: In this study, a nano-layered Cu2Se high-performance material is successfully grown using a NaCl-flux method based on the stoichiometric ratios of Cu2Se(NaCl)x (x = 1.5, 2, 2.5, 3, and 3.5).

Cited by 10 publications

References 42 publications

Synergetic Optimization of Electrical and Thermal Transport Properties by Cu Vacancies and Nanopores in Cu2Se

Synergetic Optimization of Electrical and Thermal Transport Properties by Cu Vacancies and Nanopores in Cu2Se

Thermoelectric Properties of Strained β-Cu2Se

A Self‐Independent Binary‐Sublattice Construction in Cu2Se Thermoelectric Materials

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Product

Resources

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High-performance and low thermal conductivity in nano-layered Cu₂Se prepared by a NaCl-flux method

Synergetic Optimization of Electrical and Thermal Transport Properties by Cu Vacancies and Nanopores in Cu₂Se

Synergetic Optimization of Electrical and Thermal Transport Properties by Cu Vacancies and Nanopores in Cu₂Se

Thermoelectric Properties of Strained β-Cu₂Se

A Self‐Independent Binary‐Sublattice Construction in Cu₂Se Thermoelectric Materials