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Title: Influence of Surface Ligands on Energetics at FASnI 3 /C 60 Interfaces and Their Impact on Photovoltaic Performance

Abstract

Interfacial chemistry and energetics significantly impact the performance of photovoltaic devices. In the case of Pb-containing organic metal halide perovskites, photoelectron spectroscopy has been used to determine the energetic alignment of frontier electronic energy levels at various interfaces present in the photovoltaic device. For the Sn-containing analogues, which are less toxic, no such measurements have been made. Through a combination of ultraviolet, inverse, and X-ray photoelectron spectroscopy (UPS, IPES, and XPS, respectively) measurements taken at varying thickness increments during stepwise deposition of C 60 on FASnI 3, we present the first direct measurements of the frontier electronic energy levels across the FASnI 3/C 60 interface. The results show band bending in both materials and transport gap widening in FASnI 3 at the interface with C 60. The XPS results show that iodide diffuses into C 60 and results in n-doping of C 60. This iodide diffusion out of FASnI 3 impacts the valence and conduction band energies of FASnI 3 more than the core levels, with the core level shifts displaying a different trend than the valence and conduction bands. Surface treatment of FASnI 3 with carboxylic acids and bulky ammonium substituted surface ligands results in slight alterations in themore » interfacial energetics, and all surface ligands result in similar or improved PV performance relative to the untreated devices. Finally, the greatest PV stability results from treatment with a fluorinated carboxylic acid derivative; however, iodide diffusion is still observed to occur with this surface ligand.« less

Authors:
 [1];  [1];  [1];  [1]; ORCiD logo [1]
  1. Univ. of Kentucky, Lexington, KY (United States)
Publication Date:
Research Org.:
Univ. of Kentucky, Lexington, KY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1594888
Grant/Contract Number:  
SC0018208
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 12; Journal Issue: 5; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; formamidinium tin iodide; perovskite solar cell; photoelectron spectroscopy; inverse photoelectron spectroscopy; interfacial energetics; surface modification; ion diffusion

Citation Formats

Boehm, Alex M., Liu, Tuo, Park, So Min, Abtahi, Ashkan, and Graham, Kenneth R. Influence of Surface Ligands on Energetics at FASnI 3 /C 60 Interfaces and Their Impact on Photovoltaic Performance. United States: N. p., 2019. Web. doi:10.1021/acsami.9b17535.
Boehm, Alex M., Liu, Tuo, Park, So Min, Abtahi, Ashkan, & Graham, Kenneth R. Influence of Surface Ligands on Energetics at FASnI 3 /C 60 Interfaces and Their Impact on Photovoltaic Performance. United States. https://doi.org/10.1021/acsami.9b17535
Boehm, Alex M., Liu, Tuo, Park, So Min, Abtahi, Ashkan, and Graham, Kenneth R. Mon . "Influence of Surface Ligands on Energetics at FASnI 3 /C 60 Interfaces and Their Impact on Photovoltaic Performance". United States. https://doi.org/10.1021/acsami.9b17535. https://www.osti.gov/servlets/purl/1594888.
@article{osti_1594888,
title = {Influence of Surface Ligands on Energetics at FASnI 3 /C 60 Interfaces and Their Impact on Photovoltaic Performance},
author = {Boehm, Alex M. and Liu, Tuo and Park, So Min and Abtahi, Ashkan and Graham, Kenneth R.},
abstractNote = {Interfacial chemistry and energetics significantly impact the performance of photovoltaic devices. In the case of Pb-containing organic metal halide perovskites, photoelectron spectroscopy has been used to determine the energetic alignment of frontier electronic energy levels at various interfaces present in the photovoltaic device. For the Sn-containing analogues, which are less toxic, no such measurements have been made. Through a combination of ultraviolet, inverse, and X-ray photoelectron spectroscopy (UPS, IPES, and XPS, respectively) measurements taken at varying thickness increments during stepwise deposition of C60 on FASnI3, we present the first direct measurements of the frontier electronic energy levels across the FASnI3/C60 interface. The results show band bending in both materials and transport gap widening in FASnI3 at the interface with C60. The XPS results show that iodide diffuses into C60 and results in n-doping of C60. This iodide diffusion out of FASnI3 impacts the valence and conduction band energies of FASnI3 more than the core levels, with the core level shifts displaying a different trend than the valence and conduction bands. Surface treatment of FASnI3 with carboxylic acids and bulky ammonium substituted surface ligands results in slight alterations in the interfacial energetics, and all surface ligands result in similar or improved PV performance relative to the untreated devices. Finally, the greatest PV stability results from treatment with a fluorinated carboxylic acid derivative; however, iodide diffusion is still observed to occur with this surface ligand.},
doi = {10.1021/acsami.9b17535},
url = {https://www.osti.gov/biblio/1594888}, journal = {ACS Applied Materials and Interfaces},
issn = {1944-8244},
number = 5,
volume = 12,
place = {United States},
year = {2019},
month = {12}
}

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