Synergy of Micro‐Nano Engineering Templates and Additives for FAPbI₃‐Based 1D Triangular Array Photodetector Fabrication

Abstract In optoelectronic materials, 1D arrays play a significant role in augmenting optoelectronic properties. FAPbI 3 is highly regarded for its nearly theoretical optimal bandgap and remarkable optoelectronic performance. However, black‐phase metastability and high‐reflectance light loss limit practical applications. Here, a low‐vacuum spatial confinement method with the synergy of NMP/MACl is used to fabricate stable triangular α‐FAPbI 3 ‐based 1D arrays. The low‐vacuum spatial confinement provides reaction pressure and space, guiding precursor molecules to assemble directionally, precisely defining the 1D growth mode, and forming a unique triangular low‐reflective cross‐section. NMP/MACl interact with the precursors, stabilizing the α‐phase, reducing phase‐transition barriers, and optimizing crystal growth, yielding high‐quality arrays. The impact of dimensionality on device performance is also investigated. Photodetectors based on the 1D arrays exhibit lower defect density, broader UV–vis photoresponse, and enhanced environmental stability, achieving a responsivity of (45.2 ± 3.0) A W −1 , detectivity of (1.4 ± 0.3) × 10 13 Jones, and fast response speeds of 1.2 and 1.3 µs. This work provides a practical approach for high‐quality 1D α‐FAPbI 3 ‐based perovskites and associated devices.