  Antiferromagnets are promising materials for future opto-spintronic
applications since they show spin dynamics in the THz range and no net
magnetization. Recently, layered van der Waals (vdW) antiferromagnets have been
reported, which combine low-dimensional excitonic properties with complex
spin-structure. While various methods for the fabrication of vdW 2D crystals
exist, formation of large area and continuous thin films is challenging because
of either limited scalability, synthetic complexity, or low opto-spintronic
quality of the final material. Here, we fabricate centimeter-scale thin films
of the van der Waals 2D antiferromagnetic material NiPS3, which we prepare
using a crystal ink made from liquid phase exfoliation (LPE). We perform
statistical atomic force microscopy (AFM) and scanning electron microscopy
(SEM) to characterize and control the lateral size and number of layers through
this ink-based fabrication. Using ultrafast optical spectroscopy at cryogenic
temperatures, we resolve the dynamics of photoexcited excitons. We find
antiferromagnetic spin arrangement and spin-entangled Zhang-Rice multiplet
excitons with lifetimes in the nanosecond range, as well as ultranarrow
emission linewidths, despite the disordered nature of our films. Thus, our
findings demonstrate scalable thin-film fabrication of high-quality NiPS3,
which is crucial for translating this 2D antiferromagnetic material into
spintronic and nanoscale memory devices and further exploring its complex
spin-light coupled states.
