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Issue 4, 2018
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Oxygen-induced defects at the lead halide perovskite/graphene oxide interfaces

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Abstract

Graphene oxide or its reduced derivative (GO/RGO) replace metal oxides in perovskite photovoltaics to achieve energy band alignment for minimization of the energy barriers at the film interfaces allowing efficient charge transport, and eliminate stability issues. However, the power conversion efficiencies fall in a wide range (∼0.6–18%). Therefore, the perovskite growth and nucleation on GO/RGO require fundamental understanding to improve device function for controlled fabrication, which remain a major challenge. We analyze the surface morphology and crystallization of the lead halide perovskites (MAPbX3) at 20–300 °C on GO using X-ray diffraction and photoelectron spectroscopy. To determine defect mechanisms and their composition, we perform in situ transmission infrared and micro Raman spectroscopy, and the cross-sectional scanning microscopy that captures interfacial imperfections with the oxygen defects. We demonstrate the oxygen-induced defects at the MAPbX3/GO interfaces that initiate at room temperature, and occur through the nucleophilic substitution reactions. Unexpectedly, structural defects nucleate in GO forming chemically reduced GO, and modify the surface morphology that yield a poor perovskite growth. Our theoretical studies also reveal that energetically favorable, exothermic reactions between the halides of the perovskite precursors and the oxygen groups of GO generate acidic reaction by-products (i.e. HX), that confirm the formation of oxygen-induced defects.

Graphical abstract: Oxygen-induced defects at the lead halide perovskite/graphene oxide interfaces

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Publication details

The article was received on 13 Nov 2017, accepted on 21 Dec 2017 and first published on 21 Dec 2017


Article type: Paper
DOI: 10.1039/C7TA10010H
Citation: J. Mater. Chem. A, 2018,6, 1423-1442
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    Oxygen-induced defects at the lead halide perovskite/graphene oxide interfaces

    M. Acik, I. K. Park, R. E. Koritala, G. Lee and R. A. Rosenberg, J. Mater. Chem. A, 2018, 6, 1423
    DOI: 10.1039/C7TA10010H

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