Thursday February 26 at 2:00 pm (Paris time), Room Holweck, building C, 1st floor, 10 rue Vauquelin, ESPCI, at LPEM in hybrid format: Electronic Structure of 2D Metal Halide Perovskites:
Impact of Ligands on Octahedral Twists, Energy Gaps and Exciton Binding Energy, by Antoine Kahn, Department of Electrical and Computer Engineering, Princeton Univ., Princeton, USA.
Two-dimensional (2D) halide perovskites exhibit remarkable tunability of optoelectronic properties and good environmental stability achieved through the selection of both inorganic and organic constituents. In particular, the incorporation of bifunctional ligands featuring non-ammonium terminus and functional groups capable of forming extra bonding motifs within the organic bilayer provides an effective strategy to engineer perovskite structures and introduce additional functionalities.
This talk addresses the determination of optoelectronic properties, i.e. single particle gap (EG) and exciton binding energy (EB), in several groups of Ruddlesden-Popper (RP) and Dion-Jacobson (DJ) 2D metal halide perovskites via electron spectroscopy (UPS/IPES) aided by density functional theory (DFT). We first determine the electronic gap progression as a function of inorganic layer thickness in high purity films of BA2MAn-1PbnI3n+1 (n = 1-5).[1] By subtracting the optical from the electronic gap, we show that EB vs. n ranges from 420 meV (n = 1) down to 100 meV (n = 5), well fitted by the empirical scaling law developed by Blancon et al.[2] We then turn to DJ and RP perovskites incorporating organic symmetric vs. asymmetric ligands (BDA vs. DMPD) and ligands with diverse functional groups (-CN, -OH, -COOH, -Ph, and -CH3), each exhibiting distinct bonding characteristics and dielectric properties, and report on the impact of these ligands on the electronic and excitonic properties of these 2D perovskites.[3,4] These bifunctional ligands featuring non-ammonium terminus and functional groups form extra bonding motifs within the organic bilayer and provide an effective strategy to engineer perovskite structures and introduce additional functionalities. Overall, these results provide deeper insight into the complex impact of organic ligands on the electronic and excitonic properties of 2D perovskites, in particular the substantial role of interlayer electronic coupling.
[1] X. Zhong et al., Adv. Energy Mater. 12, 2202333 (2022)
[2] J.C. Blancon et al., Nat. Commun. 9, 2254 (2018)
[3] S. Silver et al., Adv. Energy Mater. 10, 1903900 (2020)
[4] X. Zhong et al., Adv. Energy Mater., 2304345 (2024)
Impact of Ligands on Octahedral Twists, Energy Gaps and Exciton Binding Energy, by Antoine Kahn, Department of Electrical and Computer Engineering, Princeton Univ., Princeton, USA.
Two-dimensional (2D) halide perovskites exhibit remarkable tunability of optoelectronic properties and good environmental stability achieved through the selection of both inorganic and organic constituents. In particular, the incorporation of bifunctional ligands featuring non-ammonium terminus and functional groups capable of forming extra bonding motifs within the organic bilayer provides an effective strategy to engineer perovskite structures and introduce additional functionalities.
This talk addresses the determination of optoelectronic properties, i.e. single particle gap (EG) and exciton binding energy (EB), in several groups of Ruddlesden-Popper (RP) and Dion-Jacobson (DJ) 2D metal halide perovskites via electron spectroscopy (UPS/IPES) aided by density functional theory (DFT). We first determine the electronic gap progression as a function of inorganic layer thickness in high purity films of BA2MAn-1PbnI3n+1 (n = 1-5).[1] By subtracting the optical from the electronic gap, we show that EB vs. n ranges from 420 meV (n = 1) down to 100 meV (n = 5), well fitted by the empirical scaling law developed by Blancon et al.[2] We then turn to DJ and RP perovskites incorporating organic symmetric vs. asymmetric ligands (BDA vs. DMPD) and ligands with diverse functional groups (-CN, -OH, -COOH, -Ph, and -CH3), each exhibiting distinct bonding characteristics and dielectric properties, and report on the impact of these ligands on the electronic and excitonic properties of these 2D perovskites.[3,4] These bifunctional ligands featuring non-ammonium terminus and functional groups form extra bonding motifs within the organic bilayer and provide an effective strategy to engineer perovskite structures and introduce additional functionalities. Overall, these results provide deeper insight into the complex impact of organic ligands on the electronic and excitonic properties of 2D perovskites, in particular the substantial role of interlayer electronic coupling.
[1] X. Zhong et al., Adv. Energy Mater. 12, 2202333 (2022)
[2] J.C. Blancon et al., Nat. Commun. 9, 2254 (2018)
[3] S. Silver et al., Adv. Energy Mater. 10, 1903900 (2020)
[4] X. Zhong et al., Adv. Energy Mater., 2304345 (2024)
Zoom link: https://espci.zoom.us/j/81264981490?pwd=pq3Pn4NKI0ZRl3ItvjN08t1bbCvLvD.1
ID: 812 6498 1490
Passcode: Becquerel
ID: 812 6498 1490
Passcode: Becquerel
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