Langmuir-Blodgett organic films deposition for the formation of conformal 2D inorganic-organic heterostructures

Abstract

2D inorganic materials offer the opportunity to design and build heterostructures with unprecedented atomic control down to a monolayer. Integrating inorganic 2D layered materials, with the unlimited variety of organic molecules, provides a good platform for basic research and the formation of functional 2D organic-inorganic heterostructures, with tailored optoelectronic properties. In this work, we propose to employ a Langmuir-Blodgett (LB) monolayer deposition technique for the large-scale assembly of 2D inorganic-organic heterostructures. First, the transition-metal dichalcogenidemonolayers (TMDCs), MoS2 and WSe2, are grown by a chemical vapor deposition (CVD)-based method. This is followed by the LB deposition of a monolayer(s) of Zn(II)-5-(4-aminophenyl)-10,15,20-(triphenyl)porphyrin (Zn-TPP(1f)). The morphology, optical and electrical properties were systematically studied for the two TMDC systems. Despite the similarities between both TMDCs, their heterostructures with Zn-TPP(1f) monolayers show a very different optical response; a strong quenching of the photoluminescence intensity is measured for the Zn-TPP(1f)/MoS2 system, an opposite trend, PL enhancement, is obtained for the WSe2 based heterostructure. These results are explained by the differences within their electronic band diagrams, as elucidated using a wide variety of spectroscopic methodologies. The orthogonal impact on the PL emission may serve as a general platform for the formation of 2D organic-inorganic heterostructures, with controlled optical properties.