Atomically thin 2D layered semiconductor materials such as Transition Metal Di-Chalcogenides (TMDCs) have great potential for use as flexible, ultra-thin photovoltaic materials in solar cells due to their favorable photon absorption and electronic transport properties. The electronic properties, such as band structure and bandgap, and optical absorption properties of Tungsten Disulfide (WS2) were obtained from Density Functional Theory (DFT) calculations; the properties of WS2 make it a favorable photovoltaic material. DFT is a computational quantum mechanical modelling method for investigating the electronic structure and properties of many-body systems (atoms, molecules, etc.). Using these properties, a solar cell based on monolayer and bulk WS2 together with amorphous silicon (a-Si) was modelled, using numerical calculations and simulations. Our device was based on a PN junction solar cell similar to a standard silicon solar cell. The maximum efficiency of this cell is 23.26% with open-circuit voltage (VOC) of 0.843 V and short-circuit current (JSC) of 33.49 mA/cm2. The performance of this solar cell is comparable to many commercial cells. The results show how monolayer WS2 can serve as a suitable photovoltaic material, opening possibilities to develop solar cells based on 2D TMDC materials. Hybrid compounds and alloys of TMDCs are being studied for further enhancement of solar cell efficiency.
Sayan Roy is currently a 5th year Ph.D. student in Electrical Engineering at Purdue University, USA. He received the B.S. and M.S. degrees in Electrical Engineering from Purdue University in 2013 and 2017, respectively. His research interests are in nanoelectronics and photonics. His research topic is novel ultrathin materials for photovoltaic applications with a focus on Transition Metal Di-Chalcogenides (TMDCs). He was awarded the Magoon Award for Excellence in Teaching at Purdue in 2017.