# Simultaneous enhancement of power factor and suppression of thermal conductivity in bulk TlFe                    <sub>1.6</sub>                    Se                    <sub>2</sub>                    <i>via</i>                    embedded atomically thin FeSe layers

https://mdr.nims.go.jp/datasets/194361f1-76f3-4777-8e4d-ef9ceb975262

## File

- [Main Article.docx](https://mdr.nims.go.jp/filesets/83e16062-4c32-4439-bb1a-997d985aab56/download) ([Detail](https://mdr.nims.go.jp/filesets/83e16062-4c32-4439-bb1a-997d985aab56.md))

## Id

194361f1-76f3-4777-8e4d-ef9ceb975262

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2026-07-09T07:41:05.239524Z

## Updated at

2026-07-09T23:51:05.379272Z

## Published at

2026-07-10T01:24:19.310563Z

## Doi

https://doi.org/10.48505/nims.6393

## First published url

https://doi.org/10.1039/d6ta02075e

## Date published

2026-04-30

## Recorded date published

2026-6-23

## Resource type

journal_article

## Manuscript type

accepted_manuscript

## Collection



## Title

- title: |-
    Simultaneous enhancement of power factor and suppression of thermal conductivity in bulk TlFe
                        <sub>1.6</sub>
                        Se
                        <sub>2</sub>
                        <i>via</i>
                        embedded atomically thin FeSe layers
  title_type: original
  lang: en

## Description

- description: FeSe in the monolayer limit exhibits extremely large thermoelectric
    power factors (PF). Extending the high-PF concept from two-dimensional FeSe to
    bulk materials, together with lattice thermal conductivity suppression, enables
    higher-performance thermoelectrics. Here, layered TlFe1.6Se2 is identified as
    a model system consisting of atomically thin two-dimensional FeSe layers separated
    by Tl atoms; i.e., FeSe monolayers are naturally confined within a bulk crystal.
    This compound uniquely exhibits a transition from Fe-vacancy (VFe)-ordered to
    -disordered states around 200 °C. Although VFe-disordered phase exhibits high
    electrical conductivity, carrier compensation suppresses Seebeck coefficient and
    limits PF. In contrast, VFe-ordered phase shows an enhanced Seebeck coefficient
    associated with Mott gap formation, resulting in improved PF much higher than
    that of bulk FeSe. The lattice thermal conductivity of VFe-ordered phase is lower
    than those of representative thermoelectric chalcogenides, and that of VFe-disordered
    phase further decreases to ~0.2 W/(m·K) at 500 °C due to VFe-induced bond heterogeneity.
    Consequently, the dimensionless figure of merit (ZT) of TlFe1.6Se2 reaches ~0.2
    at 50 °C in VFe-ordered phase, which is two orders of magnitude higher than bulk
    FeSe. These results demonstrate that confining FeSe monolayers within a bulk crystal,
    alongside vacancy order–disorder control, is an effective design strategy for
    next-generation thermoelectrics.
  description_type: abstract
  lang: und

## Creator

- name: Xinyi He
  role: author
- name: Katsuma Ogata
  role: author
- name: Terumasa Tadano
  role: author
  orcid: https://orcid.org/0000-0002-8132-2161
- name: Hidenori Hiramatsu
  role: author
- name: Toshio Kamiya
  role: author
- name: Takayoshi Katase
  role: author
  orcid: https://orcid.org/0000-0002-2593-7487

## Contact agent



## Publisher

organization: Royal Society of Chemistry (RSC)

## Managing organization



## Keyword

- subject: Thermoelectricity
  schema: not_defined
- subject: Thermal conductivity
  schema: not_defined

## Rights

- identifier: https://creativecommons.org/licenses/by/4.0/

## Other identifier(s)



## Data origin



## Embargo



## Journal

- title: Journal of Materials Chemistry A
  issn: '20507488'
  volume: '14'
  issue: '37'
  start_page: 24666
  end_page: 24677

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## Related item



## Funding

- identifier: 20H00302
  funder_name: Japan Society for the Promotion of Science
- identifier: 21H04612
  funder_name: Japan Society for the Promotion of Science
- identifier: 22H04964
  funder_name: Japan Society for the Promotion of Science
- identifier: 24H00314
  funder_name: Japan Society for the Promotion of Science
- identifier: 24H00376
  funder_name: Japan Society for the Promotion of Science
- identifier: 24K21671
  funder_name: Japan Society for the Promotion of Science
- identifier: 25K23539
  funder_name: Japan Society for the Promotion of Science
- identifier: 26K01206
  funder_name: Japan Society for the Promotion of Science
- funder_name: Kanagawa Institute of Industrial Science and Technology
- identifier: JPMXP1122683430
  funder_name: Ministry of Education, Culture, Sports, Science and Technology
- funder_name: Tokyo Institute of Technology

## Instrument



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## Fileset

- id: 83e16062-4c32-4439-bb1a-997d985aab56
  filename: Main Article.docx
  content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
  size: 2047672
  md5: b030b59cc0a1099f2a5cdcd58967b3f2

## Thumbnail

fileset_id: 83e16062-4c32-4439-bb1a-997d985aab56
filename: Main Article.docx