Highly Efficient Perovskite/Organic Tandem Solar Cells Enabled by Mixed-Cation Surface Modulation.

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite/organic tandem solar cells (POTSCs) offer advantages like flexibility and potential efficiency beyond the Shockley-Queisser limit.
• Low power conversion efficiencies (PCEs) in wide bandgap perovskite solar cells (PVSCs) have limited their application.
• Defect-mediated non-radiative recombination is a major challenge for high-efficiency PVSCs.

Purpose of the Study:

• To develop a novel passivation strategy for wide bandgap perovskite materials.
• To improve the performance and stability of perovskite/organic tandem solar cells (POTSCs).
• To investigate the synergistic effects of mixed-cation passivators on defect reduction and recombination suppression.

Main Methods:

• A mixed-cation passivation strategy using 4-trifluoro phenethylammonium (CF3-PEA+, CA+) and ethylenediammonium (EDA2+, EA2+) was employed.
• The passivation treatment was applied to wide bandgap perovskite layers in solar cell devices.
• Device performance metrics including open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE) were measured.
• Stability tests under light soaking and thermal stress were conducted.

Main Results:

• The mixed-cation passivation effectively reduced electron/hole defect densities and non-radiative recombination rates.
• Record open-circuit voltage (Voc) of 1.35 V and fill factor (FF) of 83.29% were achieved for wide bandgap PVSCs.
• A record PCE of 24.47% was obtained for fabricated POTSCs, representing the highest reported efficiency to date.
• Unencapsulated POTSCs maintained over 90% of their initial PCE after 500 hours of operation or thermal stress at 60°C.

Conclusions:

• The synergistic effect of surface passivators is a highly promising strategy for achieving high-efficiency and stable wide bandgap PVSCs.
• This passivation approach significantly enhances the performance of perovskite/organic tandem solar cells.
• The developed method offers a viable pathway for the commercialization of efficient and durable perovskite-based solar technologies.