# Sachio Horiuchi
**Sachio Horiuchi** (堀内 佐智雄) is a Japanese materials chemist who works on organic ferroelectrics, molecular crystals in which the direction of electric polarization can be switched by an applied field. He is a Senior Chief Researcher (上級主任研究員) at the [National Institute of Advanced Industrial Science and Technology](https://www.edgepedia.org/national-institute-of-advanced-industrial-science-and-technology) (AIST) in Tsukuba, where his research fields include organic functional materials and functional solid-state chemistry.[1](https://jglobal.jst.go.jp/en/detail?JGLOBAL_ID=200901084861364868) • [2](https://researchmap.jp/horiuchi-sachio) He is known for showing ferroelectricity near room temperature in hydrogen-bonded co-crystals, for the 2008 review *Organic ferroelectrics* in *Nature Materials*, and, according to the 2010 *Nature* report, for above-room-temperature ferroelectricity in the single-component crystal croconic acid.[3](https://www.aist.go.jp/aist_e/list/latest_research/2010/20100310/20100310.html) • [4](https://doi.org/10.1038/nmat2137)
| Key fact | Detail |
|---|---|
| Field | Organic functional materials, functional solid-state chemistry, ferroelectric molecular solids[1](https://jglobal.jst.go.jp/en/detail?JGLOBAL_ID=200901084861364868) |
| Training | Kyoto University Faculty of Science (1987–1991); Graduate School of Science, Division of Chemistry (1991–1997); Doctor of Science, Kyoto University[1](https://jglobal.jst.go.jp/en/detail?JGLOBAL_ID=200901084861364868) |
| Position | Senior Chief Researcher, AIST (2017 onward; KAKEN lists the role for 2017–2025)[5](https://nrid.nii.ac.jp/nrid/1000030371074/) |
| Signature work | "Above-room-temperature ferroelectricity in a single-component molecular crystal", *Nature*, 2010 ([doi](https://doi.org/10.1038/nature08731)) |
| Croconic acid polarization | 21–22 μC cm−2 in 2010, raised to 30 μC cm−2 in 2017 |[3](https://www.aist.go.jp/aist_e/list/latest_research/2010/20100310/20100310.html) • [6](https://preview-www.nature.com/articles/ncomms14426)
| Transition range | Polarization persists to about 130 °C; no Curie point observed below 120 °C[3](https://www.aist.go.jp/aist_e/list/latest_research/2010/20100310/20100310.html) |
| Recent activity | First and corresponding author of a peer-reviewed, invited paper in *Crystals*, 19 August 2025[2](https://researchmap.jp/horiuchi-sachio) |
## Career
Horiuchi studied science at [Kyoto University](https://www.edgepedia.org/kyoto-university) from 1987 to 1991 and chemistry in its Graduate School of Science from 1991 to 1997, receiving a [Doctor of Science](https://www.edgepedia.org/doctor-of-science) from the university.[1](https://jglobal.jst.go.jp/en/detail?JGLOBAL_ID=200901084861364868) According to his J-GLOBAL researcher profile, in December 1999 he received the JRCAT Award for the development of ferroelectricity and quantum ferroelectrics using charge-transfer complexes.[1](https://jglobal.jst.go.jp/en/detail?JGLOBAL_ID=200901084861364868)
KAKEN lists his 2025 affiliation as the [Electronics](https://www.edgepedia.org/electronics) and [Manufacturing](https://www.edgepedia.org/manufacturing) domain at AIST with the title Senior Chief Researcher.[5](https://nrid.nii.ac.jp/nrid/1000030371074/) His funded projects include "Creation of Materials Science for Advanced Ferroelectrics of Organic Compounds" (2011–2016), "Studies on ferroelectric molecular solids for piezoelectric functionalities" (2016–2019), "Molecular dielectric materials: novel strong electric-field phases and new functions" (2021–2024), and a JSPS Grant-in-Aid for Scientific Research (A) from April 2021 to March 2024.[1](https://jglobal.jst.go.jp/en/detail?JGLOBAL_ID=200901084861364868) • [2](https://researchmap.jp/horiuchi-sachio) • [5](https://nrid.nii.ac.jp/nrid/1000030371074/) In March 2020 he received the AIST BEST PAPER AWARD for the 2017 *Nature Communications* paper on proton tautomerism and polarization switching.[1](https://jglobal.jst.go.jp/en/detail?JGLOBAL_ID=200901084861364868)
## Quantum phase transitions in charge-transfer complexes
The 2003 *Science* paper, published 10 January 2003 in volume 299, showed that a phase transition in an organic charge-transfer complex, originating from the neutral–ionic valence instability, can be tuned toward zero kelvin using external pressure or chemical modification as a control parameter.[7](https://doi.org/10.1126/science.1076129)
## Hydrogen-bonded co-crystal ferroelectrics and the 2008 review
In work published in *Nature Materials* in February 2005, ferroelectricity near room temperature was demonstrated in molecular compounds prepared from nonpolar conjugated acid–base molecules linked by hydrogen bonding, described as the first such attempt worldwide.[8](https://www.aist.go.jp/aist_e/list/latest_research/2005/20050201/20050201.html) The co-crystals pair phenazine (Phz) with dihydroxy-*p*-benzoquinone derivatives such as bromanilic acid (H2ba) or chloranilic acid (H2ca) in one-dimensional hydrogen-bonded networks. The transition temperature is 138 K for Phz-H2ba and 253 K for Phz-H2ca; compressing Phz-H2ca at around 6000 atm moves the transition to room temperature. At the transition the permittivity grows to a colossal value approaching 3000, in a barium-titanate-type transition driven by relative displacement of nearly nonpolar molecules.[8](https://www.aist.go.jp/aist_e/list/latest_research/2005/20050201/20050201.html)
The review *Organic ferroelectrics*, published in *Nature Materials* 7:357-366 on 24 April 2008, became a standard reference for the field ([doi](https://doi.org/10.1038/nmat2137)).[4](https://doi.org/10.1038/nmat2137)
## Croconic acid: single-component ferroelectricity above room temperature
**Representative work.** "Above-room-temperature ferroelectricity in a single-component molecular crystal", *Nature* 463:789-792, 11 February 2010, with Horiuchi as first author from AIST, Tsukuba ([doi](https://doi.org/10.1038/nature08731)).[9](https://pubmed.ncbi.nlm.nih.gov/20148035/) The paper reported ferroelectricity in croconic acid, the largest room-temperature polarization among low-molecular-weight organic compounds. Croconic acid contains only carbon, hydrogen, and oxygen, and a single molecule bears the polarization through proton movement along hydrogen-bond chains rather than a pair of ions.[3](https://www.aist.go.jp/aist_e/list/latest_research/2010/20100310/20100310.html)
The spontaneous polarization of 21–22 μC cm−2, measured with the field parallel to the hydrogen-bond chains, is close to the first-principles theoretical value of 26 μC cm−2 and comparable to barium titanate, far above the earlier organic record of 12–13 μC cm−2 for PVDF-type polymers. The field needed to reverse polarity is about 15 kV cm−1, one to two orders of magnitude smaller than for ferroelectric polymers. Polarization persists to about 130 °C, and no Curie phase-transition temperature was observed below about 120 °C, then the highest among low-molecular-weight organic ferroelectrics.[3](https://www.aist.go.jp/aist_e/list/latest_research/2010/20100310/20100310.html) In 2017, optimized switching raised the spontaneous polarization to 30 μC cm−2, exceeding some commercial ferroelectrics such as SrBi2Ta2O9 and BaTiO3, and reduced the discrepancy with first-principles calculations to less than 15%.[6](https://preview-www.nature.com/articles/ncomms14426)
## How organic ferroelectrics compare with oxides and polymers
Proton-transfer ferroelectrics of the croconic acid type offer three practical advantages. Their polarizations are comparable to or stronger than PVDF-type polymers while their coercive fields are two orders of magnitude weaker, switching at one to several tens of kV cm−1 against several hundred kV cm−1 for polymers.[6](https://preview-www.nature.com/articles/ncomms14426) They contain no lead, and their organic nature and vacuum sublimability make croconic acid a candidate for non-toxic, lead-free device applications.[10](https://pubs.rsc.org/en/content/articlelanding/2022/tc/d1tc05310h) The main practical limitation is domain-wall pinning: solution-grown crystals show strong pinning of ferroelectric domain walls, though excellent switching is recovered by thermal annealing and/or repetitive high-voltage bipolar pulses that depin the walls.[6](https://preview-www.nature.com/articles/ncomms14426)
## Applications and recent work (2016–2025)
A 2018 study of prototropic organic ferroelectrics, motivated by demand to replace lead-containing piezoceramics in electromechanical devices, found that the piezoelectric coefficient d33 correlates positively with spontaneous polarization.[11](https://pubs.rsc.org/en/content/articlelanding/2018/tc/c8tc01046c)
Horiuchi has remained active through 2025: a 2024 review of molecule-based printed electronics materials lists his affiliation as the Research Institute for Advanced Electronics and [Photonics](https://www.edgepedia.org/photonics) (RIAEP) at AIST, Tsukuba, and describes an integrated approach using cryo-electron microscopy and [X-ray free-electron laser](https://www.edgepedia.org/x-ray-free-electron-laser) methods.[12](https://pmc.ncbi.nlm.nih.gov/articles/PMC11626872/) He is first and corresponding author of the invited, peer-reviewed paper "Field-Effect Crystal Engineering in Proton-π-Electron Correlated Systems", *Crystals* 15(8):736, published 19 August 2025. His current research topics include single-component organic molecular ferroelectrics based on disk- or wheel-like molecular rotation and the wavelength dependence of electro-optic performance in croconic acid crystals.[2](https://researchmap.jp/horiuchi-sachio)
## Representative work
- **"Above-room-temperature ferroelectricity in a single-component molecular crystal"**, *Nature* (2010), [doi:10.1038/nature08731](https://doi.org/10.1038/nature08731).
## References
1. [Horiuchi Sachio | Researcher Information | J-GLOBAL](https://jglobal.jst.go.jp/en/detail?JGLOBAL_ID=200901084861364868)
2. [堀内 佐智雄 (Sachio Horiuchi) - researchmap](https://researchmap.jp/horiuchi-sachio)
3. [Discovery of Ferroelectricity of Croconic Acid, a Low-molecular-weight Organic Compound, at Room Temperature (AIST, 2010)](https://www.aist.go.jp/aist_e/list/latest_research/2010/20100310/20100310.html)
4. [Organic ferroelectrics (Nature Materials, 2008)](https://doi.org/10.1038/nmat2137)
5. [KAKEN, Researchers | Horiuchi Sachio (30371074)](https://nrid.nii.ac.jp/nrid/1000030371074/)
6. [Proton tautomerism for strong polarization switching (Nature Communications, 2017)](https://preview-www.nature.com/articles/ncomms14426)
7. [Quantum Phase Transition in Organic Charge-Transfer Complexes (Science, 2003)](https://doi.org/10.1126/science.1076129)
8. [Organic Ferroelectric Materials of Low-Molecular-Weight with Excellent Dielectric Property (AIST, 2005)](https://www.aist.go.jp/aist_e/list/latest_research/2005/20050201/20050201.html)
9. [Above-room-temperature ferroelectricity in a single-component molecular crystal (PubMed record, Nature 463:789-792, 2010)](https://pubmed.ncbi.nlm.nih.gov/20148035/)
10. [Organic ferroelectric croconic acid: a concise survey from bulk single crystals to thin films (J. Mater. Chem. C, 2022)](https://pubs.rsc.org/en/content/articlelanding/2022/tc/d1tc05310h)
11. [Piezoelectricity of strongly polarized ferroelectrics in prototropic organic crystals (J. Mater. Chem. C, 2018)](https://pubs.rsc.org/en/content/articlelanding/2018/tc/c8tc01046c)
12. [Exploration and development of molecule-based printed electronics materials (Sci. Technol. Adv. Mater., 2024)](https://pmc.ncbi.nlm.nih.gov/articles/PMC11626872/)
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*Topic: Encyclopedia › Physical world and mathematics › Physical and mathematical scientists › Chemists › Researchers in polymer, supramolecular, and materials chemistry › Conjugated and organic electronic materials*
*Initially written Sep 21, 2026 · Reviewed: Sep 25, 2026; Sep 30, 2026 · Edited: Sep 25, 2026; Sep 30, 2026; Oct 25, 2026 · Last review: Sep 30, 2026*
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