The impact of the halide cage on the electronic properties of fully inorganic caesium lead halide perovskites

Abstract

Perovskite solar cells with record power conversion efficiency are fabricated by alloying both hybrid and fully inorganic compounds. While the basic electronic properties of the hybrid perovskites are now well understood, key electronic parameters for solar cell performance, such as the exciton binding energy of fully inorganic perovskites, are still unknown. By performing magneto transmission measurements, we determine with high accuracy the exciton binding energy and reduced mass of fully inorganic CsPbX${}_3$ perovskites (X=I, Br, and an alloy of these). The well behaved (continuous) evolution of the band gap with temperature in the range $4-270$\,K suggests that fully inorganic perovskites do not undergo structural phase transitions like their hybrid counterparts. The experimentally determined dielectric constants indicate that at low temperature, when the motion of the organic cation is frozen, the dielectric screening mechanism is essentially the same both for hybrid and inorganic perovskites, and is dominated by the relative motion of atoms within the lead-halide cage.

arXiv comment7 pages, 4 figures, just accepted in ACS Energy Letters, http://pubs.acs.org/doi/abs/10.1021/acsenergylett.7b00416

References in corpus (6)

• Direct Measurement of the Exciton Binding Energy and Effective Masses for Charge carriers in an Organic-Inorganic Tri-halide Perovskite
• Relativistic Solar Cells
• Determination of the exciton binding energy and effective masses for the methylammonium and formamidinium lead tri-halide perovskite family
• Optical Phonons in Methylammonium Lead Halide Perovskites and Implications for Charge Transport
• Unraveling the exciton binding energy and the dielectric constant in single crystal methylammonium lead tri-iodide perovskite
• Spatially resolved studies of the phases and morphology of methylammonium and formamidinium lead tri-halide perovskites

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• Phonon Screening of Excitons in Semiconductors: Halide Perovskites and Beyond
• Quantifying Charge Carrier Mobilities and Recombination Rates in Metal Halide Perovskites from Time-Resolved Microwave Photo-conductivity Measurements
• Quantifying mobile ions in perovskite-based devices with temperature-dependent capacitance measurements: frequency versus time domain
• Anharmonic electron-phonon coupling in ultrasoft and locally disordered perovskites
• Giant Fine Structure Splitting of the Bright Exciton in a Bulk MAPbBr${}_3$ Single Crystal
• Static and Dynamic Disorder in Triple-Cation Hybrid Perovskites
• Calculation of the biexciton shift in nanocrystals of inorganic perovskites
• Capturing Excitonic Effects in Lead Iodide Perovskites from Many-Body Perturbation Theory
• Excitonic Bloch-Siegert shift in CsPbI3 perovskite quantum dots
• One-photon absorption by inorganic perovskite nanocrystals: A theoretical study
• Dissipation-induced symmetry breaking: Emphanitic transitions in lead- and tin-containing chalcogenides and halide perovskites
• All-order correlation of single excitons in nanocrystals using a $\mathbf{k}\cdot \mathbf{p}$ envelope-function approach: application to lead-halide perovskites
• Defect tolerance of lead-halide perovskite (100) surface relative to bulk: band bending, surface states, and characteristics of vacancies
• Intrinsic exciton transport and recombination in single-crystal lead bromide perovskite
• Binding energy of polaronic trions and biexcitons in CsPbBr${}_3$ nanocrystals
• Determining Exciton Binding Energy and Reduced Effective Mass in Metal Tri-Halide Perovskites from Optical and Impedance Spectroscopy Measurements
• Role of Inorganic Cations in the Excitonic Properties of Lead Halide Perovskites
• Between Structure and Performance in Halide Perovskites for Photovoltaic Applications: the Role of Defects
• Exciton-Selective Phonon Coupling in a Lead Halide Perovskite