Valence and conduction band tuning in halide perovskites for solar cell applications

Meloni, Simone; Palermo, Giulia; Astani, Negar Ashari; Grätzel, Michaël; Röthlisberger, Ursula

doi:10.1039/c6ta04949d

Cited by 141 publications

(148 citation statements)

References 33 publications

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“…[32] Clearly the positive value of dE g /dT that we observe in this perovskite is inconsistent with the Varshni relation, with similar behavior being reported previously in MAPbI 3 . [35,36] Our measurements show that the bandgap energy undergoes a slight redshift above 260 K, and the blueshift resumes at ≈280 K. This discontinuity is indicative of a temperature range in which a structural phase transition occurs, with this effect observed in previous studies on a range of different perovskite compositions. [35,36] Our measurements show that the bandgap energy undergoes a slight redshift above 260 K, and the blueshift resumes at ≈280 K. This discontinuity is indicative of a temperature range in which a structural phase transition occurs, with this effect observed in previous studies on a range of different perovskite compositions.…”

Section: Absorption and Photoluminescencesupporting

confidence: 74%

Correlating Phase Behavior with Photophysical Properties in Mixed‐Cation Mixed‐Halide Perovskite Thin Films

Greenland

Shnier

Rajendran

et al. 2019

Advanced Energy Materials

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Mixed cation perovskites currently achieve very promising efficiency and operational stability when used as the active semiconductor in thin‐film photovoltaic devices. However, an in‐depth understanding of the structural and photophysical properties that drive this enhanced performance is still lacking. Here the prototypical mixed‐cation mixed‐halide perovskite (FAPbI3)0.85(MAPbBr3)0.15 is explored, and temperature‐dependent X‐ray diffraction measurements that are correlated with steady state and time‐resolved photoluminescence data are presented. The measurements indicate that this material adopts a pseudocubic perovskite α phase at room temperature, with a transition to a pseudotetragonal β phase occurring at ≈260 K. It is found that the temperature dependence of the radiative recombination rates correlates with temperature‐dependent changes in the structural configuration, and observed phase transitions also mark changes in the gradient of the optical bandgap. The work illustrates that temperature‐dependent changes in the perovskite crystal structure alter the charge carrier recombination processes and photoluminescence properties within such hybrid organic–inorganic materials. The findings have significant implications for photovoltaic performance at different operating temperatures, as well as providing new insight on the effect of alloying cations and halides on the phase behavior of hybrid perovskite materials.

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Section: Absorption and Photoluminescencesupporting

confidence: 74%

Correlating Phase Behavior with Photophysical Properties in Mixed‐Cation Mixed‐Halide Perovskite Thin Films

Greenland

Shnier

Rajendran

et al. 2019

Advanced Energy Materials

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“…Consequently, this expansion reduces the overlap between Pb-6s and I-5p antibonding atomic orbitals, forming the valence band maximum (VBM; fig. S11), which increases the overall bandgap of CH 3 NH 3 PbI 3 ( 43 , 44 ). Between 120 and 150 K, that is, below the orthorhombic to tetragonal phase transition temperature of CH 3 NH 3 PbI 3 (<160 K), the experiments show two phenomena: (i) the high-energy PL peak disappears, and (ii) the low-energy peak smoothly shifts toward lower energies.…”

Section: Resultsmentioning

confidence: 99%

Origin of unusual bandgap shift and dual emission in organic-inorganic lead halide perovskites

et al. 2016

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“…Calculations show that the band gap increases with increasing lattice constant [79,80], making the slope of the linear term overall positive. The second term in the sum accounts for the renormalization of the band gap by electron-phonon coupling.…”

Section: Temperature-dependence Of the Direct Band Gapmentioning

confidence: 99%

Temperature-dependent optical spectra of single-crystal (CH3NH3)PbBr3 cleaved in ultrahigh vacuum

et al. 2017

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We measure temperature-dependent one-photon and two-photon induced photoluminescence from (CH3NH3)PbBr3 single crystals cleaved in ultrahigh vacuum. An approach is presented to extract absorption spectra from a comparison of both measurements. Cleaved crystals exhibit broad photoluminescence spectra. We identify the direct optical band gap of 2.31 eV. Below 200 K the band gap increases with temperature, and it decreases at elevated temperature, as described by the BoseEinstein model. An excitonic transition is found 22 meV below the band gap at temperatures < 200 K. Defect emission occurs at photon energies < 2.16 eV. In addition, we observe a transition at 2.25 eV (2.22 eV) in the orthorhombic (tetragonal and cubic) phase. Below 200 K, the associated exciton binding energy is also 22 meV, and the transition redshifts at higher temperature. The binding energy of the exciton related to the direct band gap, in contrast, decreases in the cubic phase. High-energy emission from free carriers is observed with higher intensity than reported in earlier studies. It disappears after exposing the crystals to air.

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Valence and conduction band tuning in halide perovskites for solar cell applications

Abstract: We performed density functional calculations aimed at identifying the atomistic and electronic structure origin of the valence and conduction band, and band gap tunability of halide perovskites ABX3 upon variations of the monovalent and bivalent cations A and B and the halide anion X.

Cited by 141 publications

References 33 publications

Correlating Phase Behavior with Photophysical Properties in Mixed‐Cation Mixed‐Halide Perovskite Thin Films

Correlating Phase Behavior with Photophysical Properties in Mixed‐Cation Mixed‐Halide Perovskite Thin Films

Origin of unusual bandgap shift and dual emission in organic-inorganic lead halide perovskites

Temperature-dependent optical spectra of single-crystal (CH3NH3)PbBr3 cleaved in ultrahigh vacuum

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