Preparation of single-phase films of CH3NH3Pb(I1–xBrx)3 with sharp optical band edges

Sadhanala, A. et al. (2014) Preparation of single-phase films of CH3NH3Pb(I1–xBrx)3 with sharp optical band edges. Journal of Physical Chemistry Letters, 5(15), pp. 2501-2505. (doi: 10.1021/jz501332v) (PMID:26277936)

Abstract

Organometallic lead-halide perovskite-based solar cells now approach 18% efficiency. Introducing a mixture of bromide and iodide in the halide composition allows tuning of the optical bandgap. We prepare mixed bromide–iodide lead perovskite films CH3NH3Pb(I1–xBrx)3 (0 ≤ x ≤ 1) by spin-coating from solution and obtain films with monotonically varying bandgaps across the full composition range. Photothermal deflection spectroscopy, photoluminescence, and X-ray diffraction show that following suitable fabrication protocols these mixed lead-halide perovskite films form a single phase. The optical absorption edge of the pure triiodide and tribromide perovskites is sharp with Urbach energies of 15 and 23 meV, respectively, and reaches a maximum of 90 meV for CH3NH3PbI1.2Br1.8. We demonstrate a bromide–iodide lead perovskite film (CH3NH3PbI1.2Br1.8) with an optical bandgap of 1.94 eV, which is optimal for tandem cells of these materials with crystalline silicon devices.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Docampo, Dr Pablo
• Authors: Sadhanala, A., Deschler, F., Thomas, T. H., Dutton, S. E., Goedel, K. C., Hanusch, F. C., Lai, M. L., Steiner, U., Bein, T., Docampo, P., Cahen, D., and Friend, R. H.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Journal of Physical Chemistry Letters
• Publisher: American Chemical Society
• ISSN: 1948-7185
• ISSN (Online): 1948-7185
• Published Online: 10 July 2014
• Copyright Holders: Copyright © 2014 American Chemical Society
• First Published: First published in Journal of Physical Chemistry Letters 5(15): 2501-2505
• Publisher Policy: Reproduced under a Creative Commons License