Improving interface quality for 1-cm² all-perovskite tandem solar cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• All-perovskite tandem solar cells offer high efficiency and low cost.
• Advances in low-bandgap perovskite bottom cells have driven efficiency gains.
• Wide-bandgap perovskite top cells face challenges with voltage and fill factor losses, especially at large areas.

Purpose of the Study:

• To develop a hole-selective layer for wide-bandgap perovskite solar cells to improve performance.
• To enable the growth of high-quality wide-bandgap perovskites over large areas.
• To reduce interfacial non-radiative recombination and enhance hole extraction.

Main Methods:

• Development of a self-assembled monolayer of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid as a hole-selective layer.
• Integration of this layer into wide-bandgap perovskite solar cells.
• Fabrication and characterization of monolithic all-perovskite tandem solar cells.

Main Results:

• Achieved a high open-circuit voltage (V_OC) of 1.31 V in a 1.77-eV perovskite solar cell with a low V_OC deficit of 0.46 V.
• Demonstrated monolithic all-perovskite tandem solar cells with 27.0% efficiency (26.4% certified stabilized) over a 1.044 cm² aperture area.
• The certified tandem cell achieved a high V_OC of 2.12 V and a fill factor of 82.6%.

Conclusions:

• The developed hole-selective layer facilitates high-quality perovskite growth and efficient hole extraction over large areas.
• This advancement is crucial for overcoming limitations in wide-bandgap perovskite top subcells.
• The successful demonstration of large-area, high-efficiency tandem solar cells marks a significant step towards the commercialization of all-perovskite photovoltaic technology.