KAUST reveals details of 33.7%-efficient perovskite-silicon tandem solar cell

A team of researchers at the King Abdullah University of Science and Technology (KAUST) has revealed the details of the 33.7%-efficient perovskite-silicon tandem solar cell that the Saudi university announced in May 2023.

In the study “Enhanced cation interaction in perovskites for efficient tandem solar cells with silicon in Science,” published in Science, the scientists explained they developed the tandem solar cell with a new perovskite additive known as tetrahydrotriazinium, which was in-situ synthesized in combination with methylenediammonium dichloride in a precursor solution.

“Our method involves using an additive strategy, which is a simple step, albeit with complex chemistry behind it, that significantly improves an already good cell platform to a better level,” Erkan Aydin, the research's corresponding author, told pv magazine. “Additionally, our compositional tuning approach enhances the phase stability of these films under heat and light conditions.”

The cell architecture was based on the tandem device that achieved a certified 32.5% efficiency in 2023, which was obtained by “focusing on the efficient interconnection of perovskite and silicon subcells, along with extreme optical management”, according to Aydin.

Research co-author Stefaan De Wolf emphasized that the laboratory-scale findings need industry cooperation before tetrahydrotriazinium is incorporated into the commercial manufacturing of perovskite-silicon tandem cells. “Our laboratory efforts to reduce performance loss at less cost is scientific. These iterative improvements can have large industrial implications, but we need partners to show how to shift our findings to a larger scale,” he said.

“The industry's response has been positive, and we are seeking industry partners to collaborate on these aspects on scaled device platforms,” Aydan added.

The 33.7%-efficient cell, which was certified by European Solar Test Installation (ESTI), had a device area of 1 cm2 and a top perovskite cell based on a p-i-n design. It also achieved an open-circuit voltage of 1.985 V, a short-circuit density of 21.02 mA cm2, and a fill factor of 81.6%.

For comparison, a reference device without tetrahydrotriazinium treatment achieved a power conversion efficiency of 32.8%, an open-circuit voltage of 1.949 V, a short-circuity density of 20.96 mA cm2, and a fill factor of 80.5%.

The treated device also showed enhanced stability after 1500 hours compared to cells manufactured without tetrahydrotriazinium. In addition, the researchers found that the non-encapsulated target perovskite-silicon tandem device retained over 82% of its initial performance after 300 minutes of maximum power point (MPP) tracking under continuous 1-sun illumination, in ambient air at 75 C, while the control device reached 80% of its initial performance within 120 minutes.

Looking ahead, Esma Unger, co-corresponding author at KAUST, told pv magazine that the long-term research goal of the KAUST KPV-LAB is to develop a realistic high-efficiency photovoltaic solution for sunny and hot climates. “At KAUST, we focus not only on creating highly efficient tandem solar cells but also on ensuring their long-term operational stability,” he stated, adding that stability and addressing the remaining challenges is the main focus now.

The work was described by researchers from KAUST and Marmara University in Turkey.

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