Circularly Polarized Photoluminescence from Chiral Perovskite Thin Films at Room Temperature

Abstract

Hybrid organic–inorganic perovskites allow the synthesis of high-quality, nanostructured semiconducting films via easily accessible solution-based techniques. This has allowed tremendous development in optoelectronic applications, primarily solar cells and light-emitting diodes. Allowed by the ease of access to nanostructure, chirality has recently been introduced in semiconducting perovskites as a promising way to obtain advanced control of charge and spin and for developing circularly polarized light sources. Circular polarization of photoluminescence (CPL) is a powerful tool to probe the electronic structure of materials. However, CPL in chiral perovskites has been scarcely investigated, and a study in bulk thin films and at room temperature is still missing. In this work, we fabricate bromine-based chiral perovskites by using a bulky chiral organic cation mixed with CsBr, resulting in Ruddlesden–Popper perovskite thin films. We measure CPL on these films at room temperature and, by using unpolarized photoexcitation, we record a degree of circular polarization of photoluminescence in the order of 10–3 and provide a full spectral characterization of CPL. Our results show that chirality is imparted on the electronic structure of the semiconductor; we hypothesize that the excess in polarization of emitted light originates from the charge in the photogenerated Wannier exciton describing an orbit in a symmetry-broken environment. Furthermore, our experiments allow the direct measurement of the magnetic dipole moment of the optical transition, which we estimate to be ≥0.1 μ B . Finally, we discuss the implications of our findings on the development of chiral semiconducting perovskites as sources of circularly polarized light.

Tuning the Circular Dichroism and Circular Polarized Luminescence Intensities of Chiral 2D Hybrid Organic–Inorganic Perovskites through Halogenation of the Organic Ions

“…The fitted lifetimes and the PLQYs were recorded and employed to calculate the radiative rate constants and the electronic transition dipole moments of the perovskite films. The calculated radiative rate constants are ranging from 3.18×10 7 to 4.53×10 7 (s −1 ) for all the films, which are similar with the reported perovskite systems (6.2×10 7 s −1 ) [25] . Meanwhile, the calculated electronic transition dipole moments show no obvious variance in the MBA perovskite system, affirming the experimental observation in absorption coefficient (vide supra).…”

“…Meanwhile, the calculated electronic transition dipole moments show no obvious variance in the MBA perovskite system, affirming the experimental observation in absorption coefficient (vide supra). Additionally, g PL values and the calculated electric transition dipole moments were employed to estimate the magnetic transition dipole moments [25–26] . The estimated magnetic transition dipole moments show the trend of 1.43×10 −1 μ B ((ClMBA) 2 PbI 4 ) > 9.58×10 −2 μ B ((BrMBA) 2 PbI 4 ) > 6.33×10 −2 μ B ((IMBA) 2 PbI 4 ) > 2.42×10 −2 μ B ((MBA) 2 PbI 4 ) > 1.17×10 −2 μ B ((FMBA) 2 PbI 4 ), where μ B is the Bohr magneton, and the trend is in good agreement with our experimental results.…”

Spin‐Dependent Charge Transport in 1D Chiral Hybrid Lead‐Bromide Perovskite with High Stability

“…such as luminescence and detection of circularly polarized light, [5,[9][10][11][12] nonlinear optics, [13] and ferroelectricity. [14,15] In recent years, the strong spin-orbit coupling [16][17][18] of heavy elements (Pb, I) offers new application opportunities of HOIPs in spintronics.…”

Polarized Photoluminescence from Lead Halide Perovskites

“…chiral perovskites, indicating that the chiral ligands have successfully implemented the chirality into the electronic structure of perovskite semiconductors. [95] The chiral ligand can not only be incorporated into the reduced dimensional perovskites but also be adopted in the nanocrystals of 3D perovskites. [45,46,97] As shown in Figure 8a, the chiral ligands (R-and S-MBABr) were used together with oleylamine ligands in preparing the FAPbBr 3 nanocrystals, to produce circular polarization in the photoluminescence signals.…”