All-perovskite tandem solar cell based on tin-lead perovskite achieves an efficiency of 28.8%

A group of researchers from Huazhong University of Science and Technology in China have fabricated an all-perovskite tandem solar cell with a wide bandgap tin-lead (Pb-Sn) perovskite top cell treated with a novel surface reconstruction strategy aimed at reducing solar radiation. Sn defects.

The proposed strategy is reportedly capable of creating high-quality Sn-Pb mixed perovskite films that can help reduce the non-radiative energy losses at the interface of the perovskite-electron transport layer. It consists of the use of 1,4-butanediamine (BDA) and ethylenediammonium diiodide (EDAI₂) as surface modifiers, which are reported to yield near-ideal stoichiometric ratio and uniform surface potential, as well as well-aligned Femi levels.

The group built a 0.0871 cm² cell with the treated Sn-Pb perovskite absorber, an electron transport layer (ETL) based on buckminsterfullerene (C60), a hole transport layer (HTL) based on PEDOT-PSS, and a gold (Au) metal contact.

The best performing BDA-EDAI₂ The modified device achieved a power conversion efficiency of 28.80%, an open-circuit voltage of 2.13 V (2.13 V), a short-circuit current density of 16.06 mA cm⁻²and a fill factor of 84.19%. “We also verified the effectiveness of the surface reconstruction in module-level devices and obtained a champion PCE of 23.39% with an opening area of ​​11.3 cm²,” said the academics.

Furthermore, they found that the encapsulated tandem cells retained 79.7% of their initial efficiency after continuous operation under Maximum Power Point Tracking (MPPT) in ambient air for 550 hours.

An unspecified third-party organization also stated that the best-performing devices achieved an efficiency of 28.49%, which the research group described as one of the highest efficiencies ever reported for all-perovskite solar cells.

“It is impressive that our Sn-Pb PSCs mixed with BDA-EDAI₂ The modification showed PCEs of 22.65% and 23.32% for 1.32 and 1.25 eV band gap, respectively, and with significantly higher open-circuit voltage and fill factor,” the academics concluded.

The new cell concept was introduced in the study “Chemical polishing and surface passivation minimize non-radiative recombination for all-perovskite tandem solar cells”, published in communication about nature.