Title: Structural and thermodynamic limits of layer thickness in 2D halide perovskites

Abstract

In the fast-evolving field of halide perovskite semiconductors, the 2D perovskites (A') ₂(A) _n-1M _nX _3n+1[where A = Cs ⁺, CH ₃NH ₃ ⁺, HC(NH ₂) ₂ ⁺; A' = ammonium cation acting as spacer; M = Ge ²⁺, Sn ²⁺, Pb ²⁺; and X = Cl ^-, Br ^-, I ^-] have recently made a critical entry. The n value defines the thickness of the 2D layers, which controls the optical and electronic properties. The 2D perovskites have demonstrated preliminary optoelectronic device lifetime superior to their 3D counterparts. They have also attracted fundamental interest as solution-processed quantum wells with structural and physical properties tunable via chemical composition, notably by the nvalue defining the perovskite layer thickness. The higher members ( n > 5) have not been documented, and there are important scientific questions underlying fundamental limits for n. To develop and utilize these materials in technology, it is imperative to understand their thermodynamic stability, fundamental synthetic limitations, and the derived structure–function relationships. We report the effective synthesis of the highest iodide n-members yet, namely (CH ₃(CH ₂) ₂NH ₃) ₂(CH ₃NH ₃) ₅Pb ₆I ₁₉( n= 6) and (CH ₃(CH ₂) ₂NH ₃) ₂(CH ₃NH ₃) ₆Pb ₇I ₂₂(more » n = 7), and confirm the crystal structure with single-crystal X-ray diffraction, and provide indirect evidence for “(CH ₃(CH ₂) ₂NH ₃) ₂(CH ₃NH ₃) ₈Pb ₉I ₂₈” (“ n = 9”). Direct HCl solution calorimetric measurements show the compounds with n > 7 have unfavorable enthalpies of formation (Δ H _f), suggesting the formation of higher homologs to be challenging. Finally, we report preliminary n-dependent solar cell efficiency in the range of 9–12.6% in these higher n-members, highlighting the strong promise of these materials for high-performance devices.« less

Authors:

Soe, Chan Myae Myae; Nagabhushana, G. P.; Shivaramaiah, Radha; Tsai, Hsinhan; Nie, Wanyi; Blancon, Jean-Christophe; Melkonyan, Ferdinand ;

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• Search OSTI.GOV for ORCID "0000-0001-8228-9247"
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Cao, Duyen H.; Traoré, Boubacar; Pedesseau, Laurent ;

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• Search OSTI.GOV for ORCID "0000-0001-9414-8644"
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Kepenekian, Mikaël ;

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• Search OSTI.GOV for ORCID "0000-0001-5192-5896"
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Katan, Claudine; Even, Jacky ;

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Marks, Tobin J. ;

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• Search OSTI.GOV for ORCID "0000-0001-8771-0141"
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Navrotsky, Alexandra ;

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• Search OSTI.GOV for ORCID "0000-0002-3260-0364"
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Mohite, Aditya D.; Stoumpos, Constantinos C.; Kanatzidis, Mercouri G.

Publication Date:

2018-12-18

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)

Sponsoring Org.:

U.S. OFFICE OF NAVAL RESEARCH

OSTI Identifier:

1576006

Resource Type:

Journal Article

Journal Name:

Proceedings of the National Academy of Sciences of the United States of America

Additional Journal Information:

Journal Volume: 116; Journal Issue: 1; Journal ID: ISSN 0027-8424

Publisher:

National Academy of Sciences

Country of Publication:

United States

Language:

ENGLISH