New design for 2T perovskite-silicon tandem solar cells with 24.6% efficiency

TU Delft scientists have built a tandem perovskite-silicon solar cell with a new approach to interface engineering. The device has an open-circuit voltage of 1.81 V, a short-circuit current of 18.1 mA/cm2, and a fill factor of 75.0%.

A research group led by Delft University of Technology in the Netherlands has developed a new solar cell for applications in perovskite-silicon tandem PV devices.

“Our findings demonstrate the potential of using (n)nc-SiOx:H and (n)nc-Si:H interfacial layers in tandem solar cells to minimize reflection losses at the interfaces between the perovskite and silicon sub-cells,” said Yifeng Zhao, the lead author of the research. “Through optimizing interference effects, these light management techniques can be applied to various tandem structures.”

The perovskite solar cell, with a 19.1% efficiency, features an indium tin oxide (ITO) and glass substrate, a carbazole (2PACz) hole transport layer, a perovskite absorber, a buckminsterfullerene (C60) electron transport layer, a bathocuproine (BCP) buffer layer, and an aluminum (Al) metal contact.

In the tandem device, a nickel(II) oxide (NiOx) layer was employed at the recombination junction to reduce electrical shunting. The presence of hydroxyl-rich NiOx facilitated the assembly of 2PACz, resulting in reduced electrical shunts in the top cells. Additionally, an anti-reflective coating based on magnesium fluoride (MgF2) and the optimization of C60 and SnOx layer thickness helped minimize reflection losses.

The champion solar cell achieved a power conversion efficiency of 24.6%, an open-circuit voltage of 1.81 V, a short-circuit current of 18.1 mA/cm2, and a fill factor of 75.0%.

By using (n)nc-Si:H and (n)nc-SiOx:H layers with thicknesses of around 95 nm and 115 nm, respectively, reflection reductions of 1.35 mA/cm2 and 1.51 mA/cm2 were achieved at the intermediate interfaces between the perovskite and c-Si bottom-cells, allowing for better light coupling into the bottom c-Si solar cells.

They presented the cell in “Optical Simulation-Aided Design and Engineering of Monolithic Perovskite/Silicon Tandem Solar Cells,” which was recently published in ACS Publications. The research group includes scientists from the Eindhoven University of Technology and the Netherlands Organisation for Applied Scientific Research (TNO).

“This technique can be adapted to different tandem designs to realize optimal light management in tandem devices,” the scientists concluded.


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