Carrier Recombination and Diffusion in Wet-Cast Tin Iodide Perovskite Layers under High Intensity Photoexcitation

Patrik Ščajev, Ramū Nas Aleksiejū Nas, Paulius Baronas, Džiugas Litvinas, Marek Kolenda, Chuanjiang Qin, Takashi Fujihara, Toshinori Matsushima, Chihaya Adachi, Saulius Juršėnas

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Abstract

Tin iodide perovskite CH3NH3SnI3 is often considered as a replacement for toxic lead halide perovskites. Tin iodide is not only suitable for production of solar cells, but also it emits in the near-infrared spectral region, which is unique among the metal halide perovskites. On the downside, the CH3NH3SnI3 layers tend to be of high unintentional p-type doping, which significantly limits the solar cell efficiency. On the other hand, it is little known how this doping could affect other optical and electrical properties important for light-emitting applications. Here, we present an optical study of carrier diffusion and recombination pathways by time-resolved photoluminescence, differential transmission, and light induced transient grating techniques at excitations close to the lasing regime. We investigate several CH3NH3SnI3 layers formed by a solvent bathing method and using different antisolvents, causing different structural quality and doping level of the layers. We observe the amplified spontaneous emission with a threshold excitation as low as 5 μJ/cm2 however, the threshold is sensitive to structural quality and increases significantly in the layers with larger surface roughness. We present an all-optical method to determine the equilibrium density of holes, which varies in the range of 0.7-5.0 × 1018 cm-3, depending on the antisolvent used for production of a particular layer. Finally, we observe band-like diffusion of carriers with high values of ambipolar diffusion coefficient: it grows from 0.5 to 1.5 cm2/s with excitation due to carrier degeneracy. High diffusivity, large quantum yield even at low densities, and low stimulated emission threshold allow us to argue that unintentional p-type doping can be beneficial for light emitting applications.

Original languageEnglish
Pages (from-to)19275-19281
Number of pages7
JournalJournal of Physical Chemistry C
Volume123
Issue number32
DOIs
Publication statusPublished - Aug 15 2019

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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    Ščajev, P., Aleksiejū Nas, R. N., Baronas, P., Litvinas, D., Kolenda, M., Qin, C., Fujihara, T., Matsushima, T., Adachi, C., & Juršėnas, S. (2019). Carrier Recombination and Diffusion in Wet-Cast Tin Iodide Perovskite Layers under High Intensity Photoexcitation. Journal of Physical Chemistry C, 123(32), 19275-19281. https://doi.org/10.1021/acs.jpcc.9b03226