Design and Manufacture of 2m² Perovskite for 4-Terminal Tandems: Achievements, and Challenges for Standards

Caelux has developed a perovskite solar panel as the top glass of a 4-terminal (4T) tandem, currently available for evaluation to Si panel manufacturers. As of December 2024 we have demonstrated >1.2m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> apertured PCE >9.8%, and subsections (259cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>) scribed from from 2.1m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> production prints have PCE near 12%. Si cells placed underneath this perovskite, as measured by one of our third-party Si panel manufacturer partners, contribute up to 9% additive efficiency. We therefore expect 4T tandems will soon surpass market-best Si panel performance. However there are significant shortcomings in the standards for testing PCE, T80 durability, and other important performance parameters of perovskites, and especially 4T tandems. In this paper we illustrate issues by example and suggest ways to resolve these shortcomings.