Scalable Cyclic Olefin Copolymer Encapsulation for High Optical Quality of TMD Monolayers

Suprova Das; Md Tarik Hossain; Zlata Fedorova; Zifei Zhang; Axel Printschler; Begimai Adilbekova; Honey Jayeshkumer Shah; Stefan Velja; Caterina Cocchi; Andrey Turchanin; Isabelle Staude

arXiv · 2608.20973

Scalable Cyclic Olefin Copolymer Encapsulation for High Optical Quality of TMD Monolayers

Suprova Das·Md Tarik Hossain·Zlata Fedorova·Zifei Zhang·Axel Printschler·Begimai Adilbekova·Honey Jayeshkumer Shah·Stefan Velja·Caterina Cocchi·Andrey Turchanin·Isabelle Staude

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Abstract

Monolayer transition metal dichalcogenides (TMDs) combine a direct bandgap, strongly bound excitons, and pronounced second-order optical nonlinearity, which makes them promising materials for ultrathin optoelectronic and nanophotonic devices. However, their optical performance is often degraded by environmental exposure and substrate-induced charge trapping, motivating the development of scalable encapsulation strategies. Here, we investigate spin-coated cyclic olefin copolymer (COC) as a scalable encapsulant for TMDs. Room-temperature and cryogenic optical spectroscopy reveal enhanced photoluminescence and second-harmonic generation, accompanied by excitonic linewidth narrowing and an increased exciton-to-trion ratio. In addition, COC encapsulation induces an excitonic peak splitting and an overall spectral blueshift. First-principles calculations attribute these spectral modifications to local symmetry breaking at the chalcogen interface and macroscopic compressive strain, respectively. These findings establish spin-coated COC as an effective, scalable encapsulation strategy and a potential platform for post-growth excitonic and band-structure engineering.

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Suprova Das, Md Tarik Hossain, Zlata Fedorova, Zifei Zhang, Axel Printschler, Begimai Adilbekova, Honey Jayeshkumer Shah, Stefan Velja, Caterina Cocchi, Andrey Turchanin, Isabelle Staude. 2026-08-21. Scalable Cyclic Olefin Copolymer Encapsulation for High Optical Quality of TMD Monolayers. https://arxiv.org/abs/2608.20973

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