Tuning the energy transfer in Ruddlesden–Popper perovskites phases through isopropylammonium addition – towards efficient blue emitters

Abstract

Metal halide perovskites are hot contenders for the next generation of light emitters. Bright and colour-pure light-emitting diodes (LEDs) were demonstrated based on bulk 3D, nanocrystals, and quasi-2D structures (Ruddlesden-Popper...

Addition of Ammonium Thiocyanate Alters the Microstructure and Energetic Landscape of 2D/3D Perovskite Films

“…46,47 More recently, some of us have reported that the addition of isopropylammonium to (PEA) 2 (Cs 0.75 MA 0.25 )Pb 2 Br 7 is capable of blocking energy transfer to phases with n > 3 by changing the texture of the perovskite film. 48 Having established that the crystallization mechanism is strongly affected by the addition of NH 4 SCN as well as the stoichiometry of the precursor solution, we then proceeded to investigate the optical properties of our films using absorption and PL spectroscopy. The 3D and ⟨n⟩ = 20 films show a clear absorption onset corresponding to the band-gap energy of MAPbI 3 around 1.58 eV, indicating the dominance of 3D or 3D-like perovskite phases in these films (Figure 4a).…”

“…The mixture of different perovskite phases in 2D/3D films constitutes an inhomogeneous energetic landscape in which energy is typically found to funnel from high-band-gap to low-band-gap phases, from which an efficient radiative recombination of charge carriers then takes place. − Several reports have demonstrated the importance of crystallization dynamics by noting that the energetic landscape is sensitive to the choice of the organic spacer cation, − solvent, , and deposition process . Even the stoichiometry of the precursor solution and variations in the ligand concentration across neighboring phases can change the photophysics of 2D/3D systems considerably. , More recently, some of us have reported that the addition of isopropylammonium to (PEA) 2 (Cs 0.75 MA 0.25 )­Pb 2 Br 7 is capable of blocking energy transfer to phases with n > 3 by changing the texture of the perovskite film . Having established that the crystallization mechanism is strongly affected by the addition of NH 4 SCN as well as the stoichiometry of the precursor solution, we then proceeded to investigate the optical properties of our films using absorption and PL spectroscopy.…”