Crystal Facet Engineering in Thermally Evaporated Ytterbium-Doped Perovskite Near-Infrared Light-Emitting Diodes.

Zhang, Shuhan; Wang, Shuo; Wei, Qilin; Li, Xin; Huang, Dan; Liu, Feng; Bi, Wengang; Chen, Zhaolai et al. · ACS Nano · 2026

basic_science · Level V

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Abstract

Quantum-cutting CsPbCl<sub>3</sub>:Yb perovskites represent a compelling class of emitters for high-performance near-infrared (NIR, >950 nm) light-emitting diodes (LEDs). The intrinsic anisotropy in dielectric response, surface termination chemistry, and strain fields across different crystallographic facets significantly influences perovskite optoelectronic performance. However, precise control over facet-selective growth in CsPbCl<sub>3</sub>:Yb thin films remains challenging due to pronounced disparities in surface and formation energies. Here, we introduce a thermal evaporation strategy to achieve controlled crystallographic orientation of CsPbCl<sub>3</sub>:Yb films for enhanced NIR emission. By modulating thermodynamic and kinetic processes, we enable selective growth of (100)- and (110)-oriented films. Comparative analysis reveals that (110)-oriented films provides a more favorable dielectric environment, resulting in stronger exciton binding and enhanced energy transfer to Yb<sup>3+</sup> ions. Leveraging this facet-guided design, our optimized device delivers an external quantum efficiency (EQE) of 7.05% and a radiance of 639 mW/sr/m<sup>2</sup> for vacuum-processed NIR (>950 nm) LEDs.