All-Round Passivation Strategy Yield Flexible Perovskite/CuInGaSe₂ Tandem Solar Cells with Efficiency Exceeding 26.5.

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Perovskite/Cu(InGa)Se2 (CIGS) tandem solar cells (TSCs) are promising for next-generation flexible and lightweight photovoltaic (PV) devices.
• Enhancing the performance of wide bandgap (WBG) perovskite solar cells (PSCs) is crucial for flexible tandem applications.
• Existing WBG PSCs require improved stability, durability, and power conversion efficiency (PCE).

Purpose of the Study:

• To introduce an effective passivation strategy for WBG PSCs within perovskite/CIGS tandem structures.
• To enhance film crystallinity and passivate defects in WBG PSCs.
• To achieve high PCE in flexible 4-terminal (4T) perovskite/CIGS TSCs.

Main Methods:

• Development and implementation of a Dual Passivation at Grains and Interfaces (DPGI) strategy.
• Application of DPGI to WBG PSCs in perovskite/CIGS tandem solar cell structures.
• Fabrication and characterization of both rigid and flexible 4T perovskite/CIGS TSCs.

Main Results:

• DPGI strategy successfully improved WBG PSC performance by enhancing film crystallinity and passivating defects.
• Substantial performance enhancement observed in WBG PSCs after DPGI implementation.
• A fully flexible 4T perovskite/CIGS TSC achieved a record power conversion efficiency (PCE) of 26.57%.

Conclusions:

• The DPGI strategy is highly effective for improving WBG PSCs in perovskite/CIGS tandem devices.
• The achieved 26.57% PCE in flexible TSCs represents a significant advancement in the field.
• This technology holds great potential for future flexible and lightweight PV tandem applications.