Title: Transition metal dichalcogenide monolayers and heterostructures for hybrid optoelectronic devices
Speaker: Dr. Sylke Blumstengel, Institut für Physik, Institut für Chemie & IRIS Adlershof, Humboldt-Universität zu Berlin, Germany
Abstract: Transition metal dichalcogenides (TMDC) hold promise as building blocks for flexible ultrathin optoelectronic devices. Their application requires the growth of continuous monolayers, heterostructures and alloys in a controlled fashion. In the talk, I will present a facile pulsed thermal deposition method which provides precise control over the number of layers and the composition of two-dimensional systems. The versatility of the method is demonstrated on ternary monolayers of Mo1-xWx S 2 and on heterostructures combining metallic TaS2 and semiconducting MoS 2 layers.
The functionality of TMDCs can be further expanded by combining them with conjugated organic molecules in hybrid structures. This is demonstrated exemplary on a MoS2 phototransistor hybridized with phthalocyanine (H2 PC) molecules. Optical spectroscopy and electrical measurements show that the spectral sensitivity of the MoS 2/H2PC phototransistor is extended into a spectral region where MoS2 is transparent. The mechanism of photocurrent generation is discussed.