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Tin selenide solar cells have so far achieved limited efficiencies in real applications. Scientists in Bangladesh claim to have found a way to dramatically improve its performance by adding a copper/indium/selenium thin film (CIS) layer and a back surface field (BSF) layer.
Researchers at the University of Rajshahi in Bangladesh have made a new attempt to design solar cells based on a tin selenide (SnSe) absorber and say their new solution could lead to the development of highly efficient devices.
“SnSe has an innate p-type electrical conductivity that raises the possibility of using it as an absorbent material in photovoltaic solar energy technology,” say the scientists, who point out that this compound has so far achieved low efficiencies in practical solar cell applications. . “According to the Shockley-Queisser index, the maximum photovoltaic conversion efficiency for each type of SnSe structure is estimated around 32%.”
The solar cell is planned to be manufactured with an indium tin oxide (ITO) substrate, an n-type cadmium sulfide (CdS) window layer with a bandgap of 2.40 eV, a p-type SnSe absorber with a bandgap of 1. 20 eV, a p-type copper/indium/selenium (CIS) thin film layer with a bandgap of 1.12 eV, a tungsten diselenide (WSe2) back surface field (BSF) layer with a bandgap of 1.65 eV and a nickel (Ni) metal contact.
In the proposed cell configuration, the CdS window has a thickness of 100 nm, which the scientists say mitigates stray absorption, and the SnSE absorber has a thickness of 600 nm, which should balance between maximizing absorption and avoid losses due to carrier recombination.
“The 200 nm thickness for the CIS magnifier represents an optimized value where a greater thickness does not significantly improve efficiency,” they further explained. “Finally, the 100 nm thickness for the WSe2 BSF was chosen because its impact was relatively low in this context.”
The research group tested the solar cell design through a series of simulations using the SCAPS-1D solar cell capacitance software, which is a simulation tool for thin film solar cells developed by Ghent University (Belgium). to model the performance of solar cells.
The researchers chose as their reference cell a single junction photovoltaic device with a power conversion efficiency of 26.12% and based solely on an SnSE absorber and a CdS layer. Their simulations showed that with the addition of the BSF layer, the cell efficiency can be raised to 33.88%, and that by adding a CIS layer it can be raised to 36.45%.
“But the final proposed n-CdS/p-SnSe/p+-CuInSe2/p++-WSe2 device is capable of generating high current and voltage,” they stated. “This figure clearly indicates that the current increases enormously to 42.54 from 38.62 mA/cm2.” The cell also achieved an open circuit voltage of 1.010 V and a fill factor of 85.01%.
The design of the solar cell was presented in the article “ Modeling and efficiency enhancement of SnSe thin film solar cell with a thin CIS layer” , published in Results in Materials . “These in-depth simulation results demonstrate the enormous potential of the SnSe absorber with the CIS current boosting layer for the creation of a thin film solar cell that is affordable and highly efficient,” the academics conclude. |
