Jump to main content
Jump to site search


Highly Oriented Two-Dimensional Formamidinium Lead Iodide Perovskite with a Small Bandgap of 1.51 eV

Abstract

Due to the quantum confinement effects, the bandgap of two-dimensional (2D) perovskites increases when the thickness of the inorganic slabs decreases. This could result in insufficient light absorption that limits the overall performance of perovskite solar cells. Here we report a series of small bandgap 2D perovskites using mixed butylammonium (BA) and formamidinium (FA) cations, i.e. (BA)2(FA)n-1PbnI3n+1 (n = 1-5). Especially, 2D perovskite (BA)2(FA)2Pb3I10 shows a small bandgap of 1.51 eV that is comparable to the state-of-the-art three dimensional perovskites. A strongly preferential out-of-plane crystallographic alignment of the inorganic perovskite component in the (BA)2(FA)2Pb3I10 film is achieved by the addition of thiourea in the precursor. This significantly improves the charge transport and thus leads to highly efficient inverted solar cells with a planar structure of ITO/PEDOT:PSS/(BA)2(FA)2Pb3I10/PC61BM/BCP/Ag. With the best power conversion efficiency of 6.88%, we demonstrated the highest PCE reported for FA based 2D perovskite solar cells. By virtue of the stable 2D perovskites, the unencapsulated device retains 80% efficiency after stored in air with a humidity of 25±5% for 25 days, indicating excellent stability against moisture and oxygen.

Back to tab navigation

Supplementary files

Publication details

The article was accepted on 04 Nov 2017 and first published on 08 Nov 2017


Article type: Research Article
DOI: 10.1039/C7QM00472A
Citation: Mater. Chem. Front., 2017, Accepted Manuscript
  •   Request permissions

    Highly Oriented Two-Dimensional Formamidinium Lead Iodide Perovskite with a Small Bandgap of 1.51 eV

    J. Yan, W. Fu, X. Zhang, J. Chen, W. Yang, W. Qiu, M. wang, F. Liu, P. Heremans and H. Chen, Mater. Chem. Front., 2017, Accepted Manuscript , DOI: 10.1039/C7QM00472A

Search articles by author

Spotlight

Advertisements