Breakthrough: Special Electrode Boosts Perovskite-Cadmium Telluride Tandem Solar Cell to 24.2% Efficiency

An international research team, led by the Indian Institute of Technology Bombay, has achieved a significant milestone in solar cell technology by developing a high-efficiency four-terminal perovskite-cadmium telluride (CdTe) tandem solar cell. This innovative device combines a top perovskite cell with an 18.3% efficiency and a bottom CdTe cell with a 19.56% efficiency, achieving an impressive overall efficiency of 24.2%.

The top perovskite cell utilizes an inverted architecture with a near-infrared transparent perovskite absorber, optimized for a bandgap of 1.63 eV. It features a crucial element—an exceptionally conductive and sputtered transparent electrode—that enhances its functionality. Developed using a customized sputtering system, this perovskite cell demonstrates a remarkable efficiency of 18.3%.

Partnering with Colorado State University, the team integrated this high-efficiency perovskite cell with a CdTe solar cell, leveraging its established commercial success in thin-film applications. The CdTe cell, supplied by collaborator Amit Munshi, achieves an efficiency of 19.56%, contributing significantly to the tandem cell's overall performance.

Key to the tandem cell's success is the index-matched interlayer between the two cells, which enhances the current density of the CdTe bottom cell. The interlayer, utilizing a refractive index-matching liquid, helps optimize light transmission and performance across the entire device.

Under standard illumination conditions, the tandem solar cell delivers impressive metrics: the top perovskite cell achieves an open-circuit voltage of 1.07 V, a short-circuit current density of 23.75 mA/cm², and a fill factor of 72.0%. Meanwhile, the bottom CdTe cell exhibits an open-circuit voltage of 0.87 V, a short-circuit current density of 27.38 mA/cm², and a fill factor of 82.1%.

The research, published in ACS Energy Letters under the title "4-T CdTe/Perovskite Thin Film Tandem Solar Cells with Efficiency >24%", marks a significant advancement in tandem photovoltaic technology. The team's approach not only demonstrates the feasibility and efficiency of CdTe/perovskite thin-film tandem solar cells but also opens new avenues beyond traditional monocrystalline silicon solar cells.

Looking ahead, the researchers aim to further optimize and scale up the tandem solar cell technology for practical applications. Their success represents a promising development towards enhancing solar energy conversion efficiency, potentially revolutionizing the field of photovoltaics with cost-effective and high-performance alternatives.

For more detailed insights, the original publication in ACS Energy Letters provides comprehensive data and analysis on the development and performance of these advanced tandem solar cells.