Toward Stable Monolithic Perovskite/Silicon Tandem Photovoltaics: A Six-Month Outdoor Performance Study in a Hot and Humid Climate
Michele De Bastiani, Emmanuel Van Kerschaver, Quentin Jeangros, Atteq ur Rehman, Erkan Aydın, Furkan H. Isikgor, Alessandro J. Mirabelli, Maxime Babics, Jiang Liu, Shynggys Zhumagali, Esma Ugur, George T. Harrison, Thomas G. Allen, Bin Chen, Yi Hou, Semen Shikin, Edward H. Sargent, Christophe Ballif, Michaël Salvador, Stefaan De Wolf
Abstract
Perovskite/silicon tandem solar cells are emerging as a high-efficiency and prospectively cost-effective solar technology with great promise for deployment at the utility scale. However, despite the remarkable performance progress reported lately, assuring sufficient device stability—particularly of the perovskite top cell—remains a challenge on the path to practical impact. In this work, we analyze the outdoor performance of encapsulated bifacial perovskite/silicon tandems, by carrying out field-testing in Saudi Arabia. Over a six month experiment, we find that the open circuit voltage retains its initial value, whereas the fill factor degrades, which is found to have two causes. A first degradation mechanism is linked with ion migration in the perovskite and is largely reversible overnight, though it does induce hysteretic behavior over time. A second, irreversible, mechanism is caused by corrosion of the silver metal top contact with the formation of silver iodide. These findings provide directions for the design of new and more stable perovskite/silicon tandems