Exciton state in two-dimensional perovskite semiconductor (C10H21NH3)2PbI4

Excitons in ultrathin organic-inorganic perovskite crystals

“…By measuring the energies of the excited states of the exciton, we deduce an excitonic binding energy of 490 ± 30 meV for the OIPCNSs. This binding energy exceeds the value for the corresponding layered bulk material (370 meV) 19,22 and of the cubic three-dimensional OIPC systems (37 meV).…”

“…In the OIPCs the smaller dielectric constant of the organic layers leads to decreased screening between the electron and the hole and, thus, to an additional increase of the exciton binding energy beyond the prediction for an idealized 2D system. 19,20,24,32,46 To probe the excitonic properties of the NSs, we measured the excitonic Rydberg series, that is, the excited states of the exciton. The allowed single-photon transitions typically involve excitonic states with zero angular momentum, which we label in analogy to the hydrogenic series by the principal quantum number as 2s, 3s, etc.…”

Colloidal lead halide perovskite nanocrystals: synthesis, optical properties and applications

“…Quantum confinement effects have been widely investigated in conventional semiconductor nanomaterials of all dimensionalities. [80][81][82] Optical properties of thin film (2D) perovskites have been studied since the late 80s, 83,84 whereas the latest developments in the size-controlled synthesis of perovskite NCs have enabled detailed investigations of quantum confinement effects in NCs. 25,29,46,50,[85][86][87] Sichert et al 25 showed that the perovskite crystal structure can be progressively reduced in a lateral dimension, yielding quasi-2D and ultimately 2D nanoplatelets with a thickness of only a single unit cell (Figure 6a).…”

Benzimidazolium Lead Halide Perovskites: Effects of Anion Substitution and Dimensionality on the Bandgap

“…The alternating arrangement of high dielectric lead halide layers and low dielectric organic layers in 2D hybrid perovskites gives rise to an inherent multiple-quantum-well structure, which results in the formation of excitons with large exciton binding energies in the metal halide sheets. [1][2][3] The dielectric confinement effect entailing a sharp excitonic absorption peak can lead to interest- 4 with the known compound (C 7 H 7 N 2 )PbI 3 reveals an increase in bandgap on going from a 2D to a dimensionally reduced 1D topology. Besides, significant differences in the PL spectra of the halides are observed, which likely are due to recombination of self-trapped excitons stabilized through lattice distortions or permanent lattice defects in the compounds featuring broad PL emission bands.…”

“…The precursors, benzimidazole and PbX 2 (X = Br, I), were mixed and ground with a few drops of the respective hydrohalic acid. (C 7 H 7 N 2 )PbI 3 was obtained phase-pure, whereas (C 7 H 7 N 2 ) 2 PbBr 4 contained a small impurity ( Figure S2, Supporting Information), which was further analyzed by energydispersive X-ray spectroscopy (EDX) and found to be a Pbrich phase displaying a needle-like morphology (Supporting Information S5). …”