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CsPbBrxI3-x thin films with multiple ammonium ligands for low turn-on pure-red perovskite light-emitting diodes


All-inorganic α-CsPbBrxI3-x perovskites featuring nano-sized crystallites show great potential for pure-red light-emitting diode (LED) applications. Currently, the CsPbBrxI3–x LEDs based on nano-sized α-CsPbBrxI3-x crystallites have been fabricated mainly via the classical colloidal route including a tedious procedure of nanocrystal synthesis, purification, ligand or anion exchange, film casting, etc. With the usually adopted conventional LED device structure, only high turn-on voltages (> 2.7) have been achieved for CsPbBrxI3-x LEDs. Moreover, this mix-halide system may suffer from severe spectra-shift under bias. In this report, CsPbBrxI3-x thin films featuring nano-sized crystallites are prepared by incorporating multiple ammonium ligands in a one-step spin-coating route. The multiple ammonium ligands constrain the growth of CsPbBrxI3-x nanograins. Such CsPbBrxI3-x thin films benefit from quantum confinement. The corresponding CsPbBrxI3-x LEDs, adopting a conventional LED structure of indium-doped tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/CsPbBrxI3-x/[6, 6]-phenyl C61 butyric acid methyl ester (PCBM)/bathocuproine (BCP)/Al, emit pure-red color at Commission Internationale de l’éclairage (CIE) coordinates of (0.709, 0.290), (0.711, 0.289), etc., which represent the highest color-purity for reported pure-red perovskite LEDs and meet the Rec. 2020 requirement at CIE (0.708, 0.292) very well. The CsPbBrxI3-x LED shows a low turn-on voltage of 1.6 V, maximum external quantum efficiency of 8.94%, high luminance of 2,859 cdm−2, and good color stability under bias.

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This work was supported by funding from the Energy Materials and Surface Sciences Unit of the Okinawa Institute of Science and Technology Graduate University (OIST), the OIST Proof of Concept (POC) Program, the OIST R&D Cluster Research Program, and the Japan Society for the Promotion of Science (JSPS) Grants-in-Aid for Scientific Research [KAKENHI] (No. JP18K05266).

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Jiang, M., Hu, Z., Ono, L.K. et al. CsPbBrxI3-x thin films with multiple ammonium ligands for low turn-on pure-red perovskite light-emitting diodes. Nano Res. 14, 191–197 (2021).

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  • CsPbBrxI3-x thin film
  • nano-sized crystallites
  • surface termination
  • pure-red color
  • perovskite light-emitting diode
  • low turn-on voltage