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A Bangladeshi research team has simulated a perovskite-CIGS photovoltaic device that can reportedly achieve a remarkable tandem cell voltage of 2.48 V. The proposed method is also applicable to tandem cells composed of other materials .
A group of researchers from Bangladesh has designed and simulated a completely inorganic and lead-free tandem photovoltaic cell based on copper, indium, gallium and selenium (CIGS) thin film technology and perovskite.
The novel architecture of the device is claimed to have the potential to achieve a power conversion efficiency of 38.39%. “The main objective of this work is to find an effective combination of non-toxic and highly efficient solar cells that saves time and effort before proceeding to their manufacture,” explain the scientists, who point out that the perovskite and the materials used for the cell They do not contain lead.
The proposed solar cell design consists of an upper cell using an absorber made of a perovskite material known as CsGe0.5Sn0.5I3 and a CIGS-based lower cell. Their structural parameters are jointly optimized to achieve the highest possible efficiency.
The scientists used SCAPS-1D solar cell capacitance software, a thin-film solar cell simulation tool developed by Ghent University, Belgium, to simulate the performance of the separately optimized top and bottom cells. “The photovoltaic cell is modeled in this software as a stack of layers, in which the thickness of each layer, doping and other physical properties of the materials that compose it are specified,” they explained.
They built the upper cell with a nickel(II) oxide (NiO) hole transport layer (HTL), the perovskite absorber, a zinc oxide (ZnO) electron transport layer, and a tin oxide layer. doped with fluorine (TFO). The bottom cell was constructed with a Spiro-OMeTAD hole transport layer, a CIGS absorber, a titanium oxide (TiO2) electron transport layer, and an indium tin oxide (ITO) layer.
The two different HTLs are reportedly capable of providing appropriate compensations of the valence and conduction band distributions.
To determine the optimal thickness of the top cell absorber, the researchers simulated the device by varying the thickness of the absorber from 100 nm to 1000 nm. “It is observed that the efficiency increases gradually from 100 nm to 1000 nm, almost begins to saturate at 800 nm and then maximizes at 1000 nm with a value of 36.25%,” they stated.
The simulation showed that the upper and lower cells can achieve a potential efficiency of 24.656% and 25.062%, respectively. “For both subcells, the current density coincides around 18.64 mA/cm2, which means the adaptation current,” the academics stated. “The results demonstrate that the voltage of the upper cell (1.4885 V) and that of the lower cell (1.0006 V) add to give a tandem cell voltage of 2.48 V, with the upper one dominating due to its relatively large open circuit voltage value.
In the simulation, the tandem cell achieved an efficiency of 38.39%, an open circuit voltage of 2.48 V, a short circuit current density of 18.64 mA cm-2 and a fill factor of 83. 40%. “The performance matrices of the proposed tandem structure exceed those of the most recent literature,” the group states.
The solar cell was featured in the article “ Outstanding conversion efficiency of 38.39% from a Perovskite/CIGS tandem PV cell: A synergic optimization through computational modeling ” : A synergistic optimization through computational modeling), published in Heliyon . The research group consists of scientists from Southeast University and the University of Liberal Arts Bangladesh.
“The steps associated with the design are generalized, so the proposed method is also applicable to tandem cells composed of other materials,” they also state. |
