Infrared transient absorption spectra for excited transition of excitons and biexcitons in CuCl

Yoshioka, Takaaki; Miyajima, Kensuke; Ashida, Masaaki; Itoh, Tadashi

doi:10.1002/pssc.200879905

Cited by 2 publications

(2 citation statements)

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“…Mixed biexcitons such as these were first described in ZnSe, InGaAs, and GaAs, where biexcitons could be formed from a heavy hole exciton and a light hole exciton. They were also observed in CuCl crystals and quantum dots, with transitions from the 1s–1s biexciton to the 1s–2s biexciton observed using infrared transient absorption. Because we have not collected 2DWL spectra after t 2 = 0, we are unable to determine if these 1s- nl ( n > 1) biexcitons relax to the 1s–1s biexciton ground state before recombining, or if they recombine directly from the initial hot state.…”

Section: Discussionmentioning

confidence: 81%

“…A hot biexciton can be thought of as an excited state of the biexciton system. Although the biexciton can be thought of as two band edge 1s excitons bound together, a hot biexciton may be composed of two different higher-energy excitons, such as 1s and 2s or 1s and 2p, or excitons of different types, such as heavy hole excitons and light hole excitons as in GaAs quantum wells. − The 2DWL spectra of n = 3 and n = 4 perovskite microcrystals (Figure b,c) exhibit similar features as the spectrum for n = 2 perovskite microcrystals, with bleaching above the bandgap and an ESA present for pump energies higher than the band edge. It appears that the ESA feature peaks with more excess pump energy with increasing n .…”

Section: Resultsmentioning

confidence: 88%

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Spatial Heterogeneity of Biexcitons in Two-Dimensional Ruddlesden–Popper Lead Iodide Perovskites

et al. 2023

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Quantum confinement in two-dimensional (2D) Ruddlesden−Popper (RP) perovskites leads to the formation of stable quasi-particles, including excitons and biexcitons, the latter of which may enable lasing in these materials. Due to their hybrid organic−inorganic structures and the solution phase synthesis, microcrystals of 2D RP perovskites can be quite heterogeneous, with variations in excitonic and biexcitonic properties between crystals from the same synthesis and even within individual crystals.Here, we employ one-and two-quantum two-dimensional whitelight microscopy to systematically study the spatial variations of excitons and biexcitons in microcrystals of a series of 2D RP perovskites BA 2 MA n−1 Pb n I 3n+1 (n = 2−4, BA= butylammonium, MA = methylammonium). We find that the average biexciton binding energy of around 60 meV is essentially independent of the perovskite layer thickness (n). We also resolve spatial variations of the exciton and biexciton energies on micron length scales within individual crystals. By comparing the one-quantum and twoquantum spectra at each pixel, we conclude that biexcitons are more sensitive to their environments than excitons. These results shed new light on the ways disorder can modify the energetic landscape of excitons and biexcitons in RP perovskites and how biexcitons can be used as a sensitive probe of the microscopic environment of a semiconductor.

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