Variation of photoluminescence of organic semiconducting-rubrene microplate depending on the thicknesses of two-dimensional MoS2 layers

Abstract

Organic semiconducting-rubrene (5,6,11,12-tetraphenyltetracene) microplates (MPs) were transferred onto the surface of two-dimensional (2-D) inorganic semiconducting molybdenum disulfide (MoS2). The nanoscale photoluminescence (PL) characteristics of the 2-D hybrid layers of the rubrene/MoS2 were measured using a high-resolution laser confocal microscope (LCM). We observed that the LCM-PL spectra of the rubrene MPs vary drastically according to the thicknesses of the 2-D MoS2 layers. When the organic-rubrene MPs were transferred onto the relatively thin MoS2 layers, the LCM-PL intensities of the rubrene MPs considerably decreased, i.e., PL quenching, because of the photoinduced charge-transfer effect between the p-type rubrene and n-type MoS2 materials. However, the LCM-PL intensities of the organic-rubrene MPs were gradually enhanced with the increasing thicknesses of the MoS2 layers due to the dominance of the reflection of the thicker MoS2 layers whereby the PL quenching is overcome. The results can be used for the data-base to improve the performance of p-n junction photovoltaic devices and light-emitting field-effect transistors.