Supramolecular Engineering for Formamidinium‐Based Layered 2D Perovskite Solar Cells: Structural Complexity and Dynamics Revealed by Solid‐State NMR Spectroscopy

• Published in: Advanced energy materials 2019-05, Vol.9 (20), p.n/a
• Main Authors: Milić, Jovana V., Im, Jeong‐Hyeok, Kubicki, Dominik J., Ummadisingu, Amita, Seo, Ji‐Youn, Li, Yang, Ruiz‐Preciado, Marco A., Dar, M. Ibrahim, Zakeeruddin, Shaik M., Emsley, Lyndon, Grätzel, Michael
• Format: Article
• Language: English
• Subjects: 2D perovskites; adamantyl; Ambient temperature; Computer architecture; Formulations; NMR spectroscopy; Perovskites; Photovoltaic cells; Solar cells; solid‐state NMR; Spectrum analysis; Stability; supramolecular design
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201900284

Perovskite solar cells are one of the most promising photovoltaic technologies, although their molecular level design and stability toward environmental factors remain a challenge. Layered 2D Ruddlesden–Popper perovskite phases feature an organic spacer bilayer that enhances their environmental stability. Here, the concept of supramolecular engineering of 2D perovskite materials is demonstrated in the case of formamidinium (FA) containing A2FAn−1PbnI3n+1 formulations by employing (adamantan‐1‐yl)methanammonium (A) spacers exhibiting propensity for strong Van der Waals interactions complemented by structural adaptability. The molecular design translates into desirable structural features and phases with different compositions and dimensionalities, identified uniquely at the atomic level by solid‐state NMR spectroscopy. For A2FA2Pb3I10, efficiencies exceeding 7% in mesoscopic device architectures without any additional treatment or use of antisolvents for ambient temperature film deposition are achieved. This performance improvement over the state‐of‐the‐art FA‐based 2D perovskites is accompanied by high operational stability under humid ambient conditions, which illustrates the utility of the approach in perovskite solar cells and sets the basis for advanced supramolecular design in the future. The case of supramolecular engineering for layered hybrid perovskites complemented by solid‐state NMR is demonstrated on A2FAn−1PbnI3n+1 formulations using (adamantan‐1‐yl)methanammonium spacers, which exhibit Van der Waals interactions complemented by structural adaptability. Efficiencies >7% for ambient temperature deposition are achieved accompanied by high stability under humid ambient conditions, highlighting its utility in perovskite solar cells.