Tunable photoluminescence in a van der Waals heterojunction built from a MoS2 monolayer and a PTCDA organic semiconductor

Abstract

We report the photoluminescence (PL) characteristics of a van der Waals (vdW) heterojunction constructed by simply depositing an organic semiconductor of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) onto a two-dimensional MoS₂ monolayer. The crystallinity of PTCDA on MoS₂ is significantly improved due to the vdW epitaxial growth. We observe an enhanced PL intensity and PL peak shift of the MoS₂/PTCDA heterojunction compared with the solo MoS₂ and PTCDA layer. The synergistic PL characteristics are believed to originate from the hybridization interaction between the MoS₂ and the PTCDA as evidenced by density functional theory calculations and Raman measurements. The hybridization interfacial interaction is found to be greatly influenced by the crystalline ordering of the PTCDA film on the 2D MoS₂. Our study opens up a new avenue to tune the PL of vdW heterojunctions consisting of TMDs and organic semiconductors for optoelectronic applications.