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Halogen Substitution as a "Chirality Editor" for Amplifying Spin-Selective Transport in Lead-Free Metal-Halide
Xinmei Liu1, Xinyi Geng1, Yuting Xu2
1Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Provincial Basic Discipline (Surface and Interface Chemistry) Research Center, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an, China.
Angewandte Chemie (International Ed. in English)
|August 14, 2026
Summary
Halogen substitution in bismuth-based hybrids enhances spin-selective transport for flexible X-ray detectors. This "chirality editing" boosts carrier mobility and detector performance, enabling sensitive radiation detection.
Area of Science:
- Materials Science
- Solid-State Physics
- Optoelectronics
Background:
- Lead-free metal-halide hybrids are promising for flexible X-ray detectors but suffer from poor carrier transport.
- Efficient spin-selective transport is crucial for enhancing detector performance.
Purpose of the Study:
- To investigate halogen substitution on chiral molecular cations as a "chirality editor" to improve carrier transport in bismuth-based hybrids.
- To establish a structure-property-performance framework for optimizing radiation detectors.
Main Methods:
- Synthesis and characterization of nine (S/rac/R-XPEA)4Bi2I10 compounds with varying halogen substitutions (F, Cl, Br).
- Investigation of chiroptical activity, Rashba spin splitting, and spin polarization efficiency using magnetoconductive atomic force microscopy.
- Fabrication and testing of optimized flexible X-ray detectors.
Main Results:
- Halogen substitution (F to Br) modulates molecular dipoles and structural distortions, enhancing Rashba spin splitting.
- Chiroptical activity increased by nearly an order of magnitude, and spin polarization efficiency rose from 68% to 89%.
- Optimized detectors showed a 3.4-fold increase in carrier mobility-lifetime product (up to 3.26 × 10⁻³ cm² V⁻¹), threefold reduced dark-current drift, high sensitivity (8865.82 ± 403 µC Gy⁻¹ cm⁻²), and low detection limit (7.16 nGy s⁻¹).
Conclusions:
- Halogen-based "chirality editing" effectively modulates the chiral electrostatic environment and amplifies spin-selective transport.
- This strategy significantly enhances carrier transport properties and device performance for flexible X-ray detectors.
- The established framework provides a pathway for designing high-performance radiation detectors based on metal-halide hybrids.
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