Research Projects

The increasing demand for high-performance, environmentally friendly, and sustainable optoelectronic devices, including wearable sensors, foldable displays, and bio-integrated sensors, has motivated research toward designing materials with tunable properties. Two-dimensional (2D) van der Waals (vdW) heterostructures, especially semiconducting transition metal dichalcogenides (TMDs), stand out due to their strong light-matter interaction, environmental stability, and tunable electronic properties (band gap, effective mass etc.). The reduced dimensionality and weak intrinsic screening in these systems enhance Coulomb interactions, leading to tightly bound excitons with binding energies of the order of hundreds of meV. Effectively controlling these electronic and excitonic properties is key to enable real-world applications. Recent advancements in twisted TMDs, created by rotational misalignment between layers, have introduced moiré superlattices that exhibit novel functionalities, including flat electronic bands, correlated electronic phases, and tunable excitonic features. However, these systems largely remain unexplored in terms of room-temperature optoelectronic applications. This proposal aims to integrate “dielectric engineering” with “twist engineering” to develop a robust platform for tunable optoelectronic applications. This combined strategy aims to address key limitations in exciton stability and tunability at room temperature by leveraging the complementary effects of dielectric and twist engineering, providing a framework for improved control over excitonic properties. By modulating the dielectric environment through high-dielectric-constant materials (e.g., HfO₂, SrTiO₃) and gate-tunable layers (e.g., bilayer graphene), we can significantly influence the electronic and excitonic properties in twisted TMD heterostructures. The proposed methodology involves a systematic experimental approach, starting with the fabrication of twisted TMD heterostructures using deterministic stacking techniques with precise twist angle control. These heterostructures will be integrated with various dielectric substrates and encapsulants, allowing local environmental modulation. The study will utilize Raman spectroscopy, photoluminescence, atomic force microscopy, and transport measurements to investigate the impact of dielectric engineering on excitonic and electronic properties. Device performance metrics such as sensitivity, response time, and stability under varying conditions will be assessed to ensure practical applicability. In summary, this project addresses critical gaps in understanding the interplay between twist angle and dielectric effects in 2D materials, advancing the design of room-temperature optoelectronic devices. The outcomes are expected to provide transformative insights into material engineering strategies, establishing twisted TMDs as a robust platform for next-generation optoelectronic technologies.