Scientists design 30.22% efficient perovskite-silicon tandem solar cell with heterojunction subtechnology – pv magazine International

22 November 2024
Emiliano Bellini

An international research team has developed a perovskite-silicon tandem solar cell using a subcell based on heterojunction (HJT) design.enhanced hole transport layers (HTLs).

“The novelty of our approach Angelika Harter, lead author of the study, said it provides a variety of innovative techniques and results for the development of perovskite-silicon tandem solar cells. pv magazine. “We increased the wettability of the perovskite layer and reduced maneuverability problems common in phosphonic acid-based conventional HTLs. methyl-substituentcontrolled carbazole (Me-4PACz). “This innovation leads to better film formation while maintaining the very good HTL properties of Me-4PACz.”

Additionally, the research group used submicron-sized textured silicon subcells, which they say overcome challenges associated with traditional micrometer-sized tissues. “These textures enable better integration of solution-processed perovskite films, reducing reflection losses and increasing light penetration, while maintaining compatibility with industrial production methods,” said Harter.

Moreover, scientists have optimized thickness of the perovskite layer and spin coating parameters; It reportedly allows efficient film formation on a submicron textured surface and demonstrates the feasibility of using cost-effective and scalable solution-based methods to fabricate high-efficiency tandem cells. “The approaches used in this work were designed to be compatible with industrial manufacturing capabilities, such as the use of commercially available Czochralski silicon wafers. Here, we demonstrate compatibility with a solution-processed supercell, also highlighting the potential for upscaling possibilities,” explained Harter.

Academics presented the new cell design in the article “Perovskite/Silicon Tandem Solar Cells Over 30% Conversion Efficiency in Submicron-Sized Textured Czochralski-Silicon Subcells with Improved Hole Transport Layerspublished in ACS Applied Materials and InterfacesThey explained that they used a sub-HJT cell textured by wet etching of random pyramids to improve reflection and passivation.

As for the perovskite film used in the top cell, they placed Me-4PACz HTL combined with smaller PA molecules at the bottom of the perovskite. “These additional PAs also enable the formation of more dipole-dipole interactions through hydrogen bridge bonding to adjacent phosphonic acid linking groups,” the group explained. “Different PAs were diluted in ethanol (EtOH) and mixed with Me-4PACz (in EtOH) at a ratio of 1:4 and spin coated onto glass/ITO samples.”

The team built the tandem device with silver (Ag) metal contacts, with passivating contacts. silicon monoxide (SiO_X), lower HJT cell, proposed HTL, a perovskite absorber, Buckminster fullerene (C60) and tin oxide (SnO2)-based electron transport layer (ETL), a transparent back contact made of indium zinc oxide (IZO), and silver (Ag) metal contact.

“After optimizing perovskite absorber fabrication for submicron tissues, proof-of-concept tandems with initial advances of the sequential application spin-annealing process of Me-4PACz with PAA enabled a champion device with 30.22% power conversion efficiency double sided submicron-sized textured Cz-Si SHJ subcell with open-circuit voltage up to 1.954 V and up to 1.954 V achieves stabilized efficiency of 30.15%,” the researchers said.

“Overall, we exhibit a high total short-circuit current density of 40.35 mA/cm²“This is remarkable considering the use of an industrially suitable silicon subcell that is only 140 μm thick and has one of the highest values ​​reported for a thin Cz material,” they added.

Going forward, the research team plans to explore the use of sequential spin coating with an intermediate annealing step to further improve the performance of the cell, he said.

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