Giant Fine Structure Splitting of the Bright Exciton in a Bulk MAPbBr3 Single Crystal.
Nano letters (2019)
Abstract:Exciton fine structure splitting in semiconductors reflects the underlying symmetry of the crystal and quantum confinement. Since the latter factor strongly enhances the exchange interaction, most work has focused on nanostructures. Here, we report on the first observation of the bright exciton fine structure splitting in a bulk semiconductor crystal, where the impact of quantum confinement can be specifically excluded, giving access to the intrinsic properties of the material. Detailed investigation of the exciton photoluminescence and reflection spectra of a bulk methylammonium lead tribromide single crystal reveals a zero magnetic field splitting as large as ~200μeV. This result provides an important starting point for the discussion of the origin of the large bright exciton fine structure observed in perovskite nanocrystals.
Revealing the nature of photoluminescence emission in the metal-halide double perovskite Cs2AgBiBr6
JOURNAL OF MATERIALS CHEMISTRY C 7:27 (2019) 8350-8356
Photovoltaic solar cell technologies: analysing the state of the art
Nature Reviews Materials Nature Research 4:4 (2019) 269-285
Impact of Bi3+ heterovalent doping in organic-inorganic metal halide perovskite crystals
Journal of the American Chemical Society American Chemical Society 140:2 (2018) 574-577
Abstract:Intrinsic organic-inorganic metal halide perovskites (OIHP) based semiconductors have shown wide applications in optoelectronic devices. There have been several attempts to incorporate heterovalent metal (e.g., Bi3+) ions in the perovskites in an attempt to induce electronic doping and increase the charge carrier density in the semiconductor. It has been reported that inclusion of Bi3+ decreases the band gap of the material considerably. However, contrary to the earlier conclusions, despite a clear change in the appearance of the crystal as observed by eye, here we show that the band gap of MAPbBr3 crystals does not change due the presence of Bi3+ in the growth solution. An increased density of states in the band gap and use of very thick samples for transmission measurements, erroneously give the impression of a band gap shift. These sub band gap states also act as nonradiative recombination centers in the crystals.
The effect of ionic composition on acoustic phonon speeds in hybrid perovskites from Brillouin spectroscopy and density functional theory
JOURNAL OF MATERIALS CHEMISTRY C 6:15 (2018) 3861-3868