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

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.m.