Enhanced Contrast to Circularly Polarized Excitation in Large-Area Continuous MoS2 Monolayer Coupled to Plasmonic Spiral Arrays

Most applications in optoelectronics that utilise two-dimensional transition metal dichalcogenides (TMDs) are currently limited to micron sizes, making the scalability of these devices practically significant. This study investigates the interaction between plasmonic arrays featuring Archimedes spiral patterns and large-area MoS2 films measuring 1 cm². Despite the presence of defect states in these large-area MoS2 monolayers, we recorded a maximum 40% contrast in photoluminescence when comparing left- and right-circularly polarised excitation, with a degree of polarisation of 0.3{plus minus}0.1, considering positional variation using a wide field excitation. We found that bringing the spirals closer together enhances the contrast of the degree of polarisation in the absence of the diffractive lattice mode. Our study demonstrates the potential of large-area TMD-based devices and underscores the importance of improving or engineering material quality to achieve device performances comparable to those based on micrometre-sized TMD flakes.