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Title: Direct calorimetric verification of thermodynamic instability of lead halide hybrid perovskites

Hybrid perovskites, especially methylammonium lead iodide (MAPbI 3), exhibit excellent solar power conversion efficiencies. However, their application is plagued by poor chemical and structural stability. In this paper, using direct calorimetric measurement of heats of formation, MAPbI 3 is shown to be thermodynamically unstable with respect to decomposition to lead iodide and methylammonium iodide, even in the absence of ambient air or light or heat-induced defects, thus limiting its long-term use in devices. The formation enthalpy from binary halide components becomes less favorable in the order MAPbCl 3, MAPbBr 3, MAPbI 3, with only the chloride having a negative heat of formation. Finally, optimizing the geometric match of constituents as measured by the Goldschmidt tolerance factor provides a potentially quantifiable thermodynamic guide for seeking chemical substitutions to enhance stability.
Authors:
 [1] ;  [1] ;  [1]
  1. Univ. of California, Davis, CA (United States). Peter A. Rock Thermochemistry Lab. Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit
Publication Date:
Grant/Contract Number:
FG02-03ER46053
Type:
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 113; Journal Issue: 28; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Univ. of California, Davis, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; hybrid halide perovskites; thermodynamic instability; solar cells; tolerance factor; enthalpy of formation
OSTI Identifier:
1259914
Alternate Identifier(s):
OSTI ID: 1470072