Band alignment and interlayer hybridization in monolayer organic/WSe2 heterojunction

This is the authors' abstract. We don't add key points for this paper.

Semiconducting heterojunctions (HJs), comprised of atomically thin transition metal dichalcogenides (TMDs), have shown great potentials in electronic and optoelectronic applications. Organic/TMD hybrid bilayers hold enhanced pumping efficiency of interfacial excitons, tunable electronic structures and optical properties, and other superior advantages to these inorganic HJs. Here, we report a direct probe of the interfacial electronic structures of a crystalline monolayer (ML) perylene-3,4,9,10-tetracarboxylic-dianhydride (PTCDA)/ML-WSe 2 HJ using scanning tunneling microscopy, photoluminescence, and first-principle calculations. Strong PTCDA/WSe 2 interfacial interactions lead to appreciable hybridization of the WSe 2 conduction band with PTCDA unoccupied states, accompanying with a significant amount of PTCDA-to-WSe 2 charge transfer (by 0.06 e/PTCDA). A type-II band alignment was directly determined with a valence band offset of ∼ 1.69 eV, and an apparent conduction band offset of ∼ 1.57 eV. Moreover, we found that the local stacking geometry at the HJ interface differentiates the hybridized interfacial states.