Synthesis and Light-Matter Interaction of Low-Dimension Ordered-Disordered Layered Semiconductors

Well-structured and ordered 2D layered semiconducting materials have excellent optical properties but limited advanced optoelectronic applications in their natural state. Altering their natural arrangement, through artificial heterostructures, strain and pressure engineering, chemical doping, intercalation, and alloying, can impart them with unusual optical properties and potentially enhance their performance in various applications. Among these approaches, alloying is generally difficult to control and disrupts the well-ordered homophilic crystal phase of these 2D crystals, albeit with the capability to control materials as thin as a single atomic layer. In this work, the synthesis of a low-dimension ordered-disordered layered 2D alloy of Mo_(1-x)W_xSe₂ with clearly ordered in-plane segregations of nano-sized islands of individual MoSe₂ and WSe₂ across the material surface is reported. The optical analysis of this ordered-disordered layered Mo_(1-x)W_xSe₂ reveals unique interfacial and interlayer coupling physics, such as the co-existence of intralayer (interfacial) and interlayer excitons and enhanced valley polarization of up to 50%, which is traditionally absent in ordered MoSe₂, WSe₂, or their heterostructures. Furthermore, the structure exhibits implies open circuit voltage (up to 1130 mV), signifying its excellent open-circuit voltage potential if employed in photovoltaic devices. Overall, the reported low-dimension ordered-disordered semiconductor alloys can be useful in various optoelectronic applications.