Low-Temperature Growth of Centimeter-Sized 2D PdSe2 by Self-Limiting Liquid-Phase Edge Epitaxy

Two-dimensional (2D) PdSe₂ atomic crystals hold great potential for optoelectronic applications due to their bipolar electrical characteristics, tunable bandgap, high electron mobility, and exceptional air stability. Nevertheless, the scalable synthesis of large-area, high-quality 2D PdSe₂ crystals using chemical vapor deposition (CVD) remains a significant challenge. Here, we present a self-limiting liquid-phase edge-epitaxy (SLE) low-temperature growth method to achieve high-quality, centimeter-sized PdSe₂ films with single-crystal domain areas exceeding 30 μm. The SLE growth mechanism, clarified by theoretical calculations and time-of-flight secondary ion mass spectrometry (ToF-SIMS), reveals that hydrogen ions on the precursor surface inhibit vertical growth while promoting lateral growth. The as-grown PdSe₂ few-layer exhibits a surface roughness of 1.20 nm and an average conductivity of 1.67 × 10^-6 S/m, demonstrating their smoothness and uniformity. Temperature-dependent electrical measurements and transfer characteristic curves confirm the orthorhombic PdSe₂'s bipolar semiconductor behavior. The photodetector based on few-layer PdSe₂ films exhibit excellent optoelectronic performance in the 405-1650 nm wavelength range, achieving a responsivity of 6262.37 A W^-1, a detectivity of ∼10¹² Jones under 1064 nm illumination, and a fast response time of 37.1 μs, making them highly suitable for broadband photodetection applications. This work provides valuable insights into the scalable synthesis of PdSe₂ few-layers and establishes a foundation for the development of PdSe₂-based integrated functional devices.