Solar Cell

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Technology description Researchers at George Washington University have recently developed an improved Solar Cell material.  While photovoltaic cells based on semiconducting two-dimensional (2D) transition metal dichalcogenides exhibit strong light absorption relative to its thickness; the reported photo absorption is still just a few percent due to their thinness, causing low overall cell efficiencies. However, taking advantage of the mechanical flexibility of 2D materials by rolling a stack to make a spiral solar cell can increase sola absorption up to 90%. The multi-layered cylinder structure is responsible for enhanced light matter interaction and hence for raising the absorption from ~10% for the planar structures to 90% for the cylindrical structures. The researchers have come up with 2 different designs with same basic idea: a) Spiral Cell Structure b) Core-shell Structure as show in the following figure.  Experiments show that planar solar cells using stack of  Graphene, 1 mm thick MoS2, and gold could give current density of about 25.5 mA/cm2 while for spiral structures resulting spectral current density is about 30-43 mA/cm2. The spiral design enables light absorption enhancement (~50%) within only ~10% of the photoactive material used in the conventional planar structures. This design has implemented unique way for enhanced Light Matter Interaction. The power conversion efficiency of these designs range currently ranges up to 13% which is equivalent to current nano-solar cell structures. It is expected that future improvements in growth of these novel materials and design combination can achieve much higher efficiencies.