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There is a great demand for high performance materials and technology in space photovoltaics (PV) to meet the power needs of satellites. Transition Metal Di-Chalcogenides (TMDCs) are strong candidates for such applications, as they are very lightweight and resilient to high energy radiation, compared to most PV semiconductors. We have modeled an ultra-thin photovoltaic system based on tungsten disulfide (WS2) and demonstrated performance enhancement by addition of light trapping and anti-reflection coating. Our photovoltaic model consists of a 100 nm thick WS2-based heterojunction solar cell, similar to the Hetero Junction Intrinsic Thin Layer (HIT) solar cell structure. A 1-D grating light trapping structure has been implemented using silver as the reflector material, with the grating period and thickness optimized for highest absorption enhancement. An antireflection coating layer was added to further enhance absorption, with the thickness optimized to minimize surface reflection. We have simulated our model under AM0 solar spectrum over the temperature range of geostationary satellite orbits (313-343K). The baseline photovoltaic model design was calculated to have an efficiency around 12%. The absorption enhancement from light trapping increased the short-circuit current (JSC) by 25%, which gave an efficiency around 16%. The additional absorption due to anti-reflection coating increased the JSC by a further 15%, leading to efficiency around 19%. In addition, TMDC-based solar cells have lower temperature coefficient for efficiency degradation compared to low bandgap semiconductor solar cells. These results show that our TMDC-based photovoltaic system with light trapping and anti-reflection coating is a strong candidate for space photovoltaic applications.
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