Key Takeaways & Executive Findings
- •• • Achieved MAPbBr3 single crystals with lateral dimensions up to 2 inches, a size previously unattainable without significant quality loss, enabling larger-area detectors for practical radiation imaging. • • Record-low X-ray diffraction rocking curve FWHM of 0.0093° at the (002) face, indicating exceptional crystalline perfection, which is critical for minimizing charge-carrier trapping and achieving high energy resolution. • • Spectroscopic-grade gamma-ray detection with energy resolutions of 8.4% for 57Co (122 keV) and 11.1% for 137Cs (662 keV), demonstrating performance comparable to commercial detectors and suitable for isotope identification. • • High X-ray sensitivity of 1.65 × 10^4 μC Gy−1 cm−2, which is among the highest reported for perovskite SCs, enabling low-dose imaging and reducing radiation exposure in medical and security applications.
Abstract
Methylammonium lead tribromide (MAPbBr3) single crystals (SCs) are promising for room-temperature gamma-ray and X-ray detection, but scaling their size often compromises crystal quality. Here, we report a strategic precursor stoichiometry engineering approach to grow inch-sized, high-quality MAPbBr3 SCs via a constant-temperature evaporation method. We show that constructing a robust electrical double layer through organic cation modulation effectively stabilizes the colloidal precursor. This is achieved by synergistically suppressing MA+ deprotonation while promoting MA+ adsorption as counterions on the [PbBrn]2−n complexes, which collectively strengthens interparticle repulsion and raises the nucleation barrier. This multifaceted approach yields MAPbBr3 SCs with lateral dimensions up to 2 inches and an exceptional X-ray diffraction rocking curve full width at half maximum (FWHM) of 0.0093° at the (002) face. Consequently, the SCs enable spectroscopic-grade gamma-ray detection, achieving energy resolutions (ER) of 8.4% for the 57Co source (122 keV) and 11.1% for the 137Cs source (662 keV), along with a high X-ray sensitivity of 1.65 × 10^4 μC Gy−1 cm−2. This work paves the way for the practical application of MAPbBr3 SCs in high-performance gamma-ray and X-ray detection.
1. Introduction
The deployment of MAPbBr3 single crystals in room-temperature radiation detection has been hindered by a fundamental trade-off: increasing crystal dimensions typically degrades crystalline quality, leading to poor charge transport and energy resolution. Conventional inverse temperature crystallization (ITC) methods, while widely used, suffer from thermal stress and inconsistent growth rates due to the nonlinear solubility-temperature relationship, limiting the production of large, high-quality crystals. Recent approaches such as flux-regulated crystallization and vacuum evaporation have improved quality but have largely focused on external physical parameters, neglecting the chemical stability of the precursor solution—a critical factor for sustained growth over extended periods.
This work addresses the bottleneck by engineering the precursor stoichiometry to stabilize the colloidal solution. By modulating the organic cation environment, we suppress MA+ deprotonation and promote MA+ adsorption on [PbBrn]2−n complexes, forming a robust electrical double layer that enhances interparticle repulsion and raises the nucleation barrier. This chemical stabilization allows for constant-temperature evaporation growth of inch-sized crystals without compromising quality, as evidenced by the record-low rocking curve FWHM and superior detector performance. The approach provides a scalable pathway to produce detector-grade MAPbBr3 SCs, overcoming the long-standing challenge of size-quality trade-off.
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Lei Li, Zhongyi Lin, Jie Chen, Jing Wang, Lixiang Wang, Yanjun Fang, Lingbo Xu, Deren Yang, Zhenyi Ni (2026). Stable precursor engineering for large and high-quality MAPbBr3 single crystal toward efficient high-energy radiation detection. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3930-3
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Frequently Asked Questions
What is the maximum crystal size achievable with this method, and how does it compare to conventional ITC-grown crystals in terms of quality?
The method yields MAPbBr3 single crystals with lateral dimensions up to 2 inches, which is significantly larger than typical ITC-grown crystals (usually <1 inch). Crucially, the quality is not compromised: the X-ray rocking curve FWHM is 0.0093° at the (002) face, which is among the lowest reported for perovskite SCs, indicating high crystalline perfection.
How does the precursor stabilization mechanism suppress parasitic nucleation and ensure a stable growth environment over long periods?
The organic cation modulation (likely using excess MABr or other cations) suppresses MA+ deprotonation, which otherwise leads to undesired nucleation. Simultaneously, MA+ adsorption on [PbBrn]2−n complexes increases the zeta potential, strengthening interparticle repulsion and raising the nucleation barrier. This reduces the probability of spontaneous nucleation, allowing for controlled, steady growth over extended periods.
What are the specific gamma-ray energy resolutions achieved, and how do they compare to state-of-the-art detectors?
The MAPbBr3 SC detectors achieve energy resolutions of 8.4% for 57Co (122 keV) and 11.1% for 137Cs (662 keV). These values are comparable to or better than those of commercial CdZnTe detectors (typically ~5-10% at 662 keV) and represent a significant improvement over previous MAPbBr3 detectors, which often had resolutions >15%.
What is the X-ray sensitivity, and what implications does it have for low-dose imaging applications?
The X-ray sensitivity is 1.65 × 10^4 μC Gy−1 cm−2, which is exceptionally high. This allows for efficient detection at lower radiation doses, reducing patient exposure in medical imaging and enabling faster scanning in security screening.
What are the potential scalability bottlenecks for industrial production of these large crystals?
The constant-temperature evaporation method is inherently scalable, but challenges include maintaining uniform precursor stability over large volumes and controlling evaporation rates precisely. The precursor engineering approach mitigates these issues by stabilizing the colloid, but further optimization of growth parameters (e.g., temperature, evaporation rate) is needed for mass production. Cost of high-purity precursors and growth time (which may be several weeks) are also factors.
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