Supramolecular interactions using β-cyclodextrin in controlling perovskite solar cell performance

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2024-07, Vol.12 (26), p.15837-15846
• Main Authors: Ferdowsi, Parnian, Kim, Sun-Ju, Nguyen, Thanh-Danh, Seo, Ji-Youn, Yum, Jun-Ho, Sivula, Kevin
• Format: Article
• Language: English
• Subjects: Cations; Crystal defects; Crystal growth; Crystallization; Cyclodextrins; Energy conversion efficiency; Iodides; Maltose; Perovskites; Photovoltaic cells; Precursors; Solar cells; Stability; Thermal stress; β-Cyclodextrin
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d4ta01741b

In the context of perovskite solar cells (PSCs), enhancing device performance often involves adding a small excess of lead iodide (PbI 2 ) to the precursor solution. However, the presence of unreacted PbI 2 can lead to accelerated degradation compromising long-term stability. This study addresses this issue through supramolecular complex engineering by introducing beta-cyclodextrin (β-CD) into a triple cation perovskite to effectively prevent the crystallization of residual PbI 2 . This approach results in uniform crystal growth and the passivation of undercoordinated lead cation defects. The use of β-CD leads to a PSC with an improved power conversion efficiency (PCE) of 21.36%, surpassing the control, and enhanced stability against aggressive thermal stress and high humidity (85% RH). This is supported by optical and morphological investigations, underscoring the role of β-CD to maintain the desired perovskite phase. Notably, in comparison to the β-CD-free control, the β-CD-treated sample exhibited minimal bandgap shifts of 3 meV after 1170 hours of moisture exposure. Furthermore, this method not only passivates unreacted PbI 2 but also provides valuable insights into the role of β-CD in hybrid perovskite solar cells. Additional tests with maltose as a non-cyclic control were conducted and confirm the superior ability of β-CD to enhance perovskite film stability under harsh conditions. The formation of a supramolecular system between β-CD and perovskite holds promise as a strategy to control perovskite precursor chemistry, material structure, and subsequent device performance and stability. By incorporating β-cyclodextrin, mitigation of residual PbI 2 crystallization, control of perovskite chemistry, and uniform crystal growth, leading to improved solar cell performance and stability were demonstrated.