Materials Today
Volume 38, September 2020, Pages 67-83
Journal home page for Materials Today

Research
Methodologies for structural investigations of organic lead halide perovskites

https://doi.org/10.1016/j.mattod.2020.03.025Get rights and content

Abstract

Fundamentally, organic lead halide perovskites (OLHPs), which have attracted tremendous attention in the field of photovoltaic technology, are the materials organized in the platform of a perovskite structure by hybridizing the organic component with the inorganic lead halide. In understanding the highly efficient photovoltaic performance of perovskite solar cells (PSCs), crystallographic investigation of OLHPs has been an accompanying field of study because opto-electronic properties are believed to be closely related to their crystal structure. This article reviews the progress of the structural investigations of OLHPs. Macro-scale structural analyses, including X-ray diffraction, are discussed to introduce the investigation methods for the overall properties of OLHPs. Subsequently, the progresses of the microstructural investigations, such as transmission electron microscopy, are described to understand the situation of the micro-scale crystallographic approaches that were achieved recently. In addition, electron damages, which are the obstacles for the structural investigation of OLHPs in electron microscopy, are discussed, and the methodologies alleviating the electron damages are introduced. Based on this review, we believe that the advances in structural investigations are crucial for further advancements in the research on the OLHPs for PSCs and related applications.

Introduction

Since the emergence of solid-state perovskite solar cells (PSCs) in 2012 (Fig. 1) [1], [2] following attempts which tried to utilize the perovskite materials as a sensitizer for liquid junction solar cells [3], [4], organic lead halide perovskites (OLHPs) have attracted enormous attention [5], [6], [7], [8] as the leader of the next generation photovoltaic materials. This great attention is based on the remarkable accomplishments in their solar cell application [9], [10], [11], [12], [13], [14], [15]. Consequently, the PSCs have achieved a certified power conversion efficiency (PCE) of 25.2% exceeding top records of some conventional solar cells [16]. The unprecedented achievements are generated from the superb characteristics of OLHPs [17], [18], [19], [20], [21], [22]. As the special properties of OLHPs originated from their unique crystallographic characteristics based on the hybrid of organic and inorganic components which are different from conventional perovskite materials, the structural investigation of OLHPs has been considered to be one of the most critical points for deep understanding of them. For this reason, there have been various structural investigations of OLHPs by using diverse analysis approaches such as X-ray diffraction (XRD) and transmission electron microscopy (TEM). As a result, various important structural information of OLHPs including phase transformation has been reported. Even though multiple structural investigations of OLHPs have been reported, details of their structural characteristics are still disputed due to various obstacles caused by their vulnerability during structural investigation. Therefore, advanced structural analysis of OLHPs is strongly needed.

In this article, the structural analysis approaches, which have been used for the understanding of OLHPs, will be reviewed from macro- to micro-scale. In the macro-scale structural investigation, the progress of XRD analysis, photoluminescence spectroscopy (PL), and optical spectroscopy is discussed based on the development of OLHPs. For the micro-scale structural investigation methods, atomic force microscopy (AFM) and electron microscopies are treated. Moreover, the limits in the electron microscopies caused by electron beam damage on the specimen are described to provide a careful and precise analysis.

Section snippets

Macro-scale structure analysis for OLHPs

Perovskite is the name of the crystal structure originating from calcium titanium oxide (CaTiO3). CaTiO3 consists of TiO6 and Ca which occupy octahedra and cubo-octahedral cavity, respectively. Based on CaTiO3, the perovskite structure refers to the crystal structure of the materials with an ABX3 formula such as SrTiO3 and BaTiO3. The structure of OLHP is also constructed as ABX3 stoichiometry, where A is an organic cation [e.g., CH3NH3+ (MA+)], B is a metal ion (e.g., Pb2+), and X is a halogen

Atomic force microscopy (AFM)

AFM is an analysis approach which visualizes the surface of the objects with the information induced by Van der Waals interaction between a cantilever of the AFM and the surface of the specimen. In the PSCs field, the AFM has been utilized for the investigation of the surface morphology [51], [58], [59] or roughness [54], [92], [93], [94] (Fig. 8a–e). The AFM has been used not only for the investigation of morphology but also for further investigation such as conductivity via its modification.

Conclusions and perspective

OLHPs have shown remarkable performances in photovoltaic field and have become one of the leading materials for next generation energy conversion technologies and opto-electronics. Interestingly, OLHPs have demonstrated somewhat unique characteristics different from the conventional semiconducting materials. As they are the materials constructed on the basis of the “perovskite” crystal structure by “hybridizing” the organic and inorganic components, the unique characteristics must be treated

Acknowledgements

This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Ministry of Science, ICT Future Planning (MSIP) of Korea under contracts NRF-2012M3A6A7054861 (Global Frontier R&D Program on Center for Multiscale Energy System), NRF-2016M3D1A1027663 and NRF-2016M3D1A1027664 (Future Materials Discovery Program), and NRF-2015M1A2A2053004 (Climate Change Management Program).

References (152)

  • N.G. Park

    Mater. Today

    (2015)
  • N. Onoda-Yamamuro

    J. Phys. Chem. Solids

    (1992)
  • R. Kang

    Nano Energy

    (2016)
  • H.S. Kim

    Sci. Rep.

    (2012)
  • M.M. Lee

    Science

    (2012)
  • A. Kojima

    J. Am. Chem. Soc.

    (2009)
  • J.H. Im

    Nanoscale

    (2011)
  • N.G. Park

    J. Phys. Chem. Lett.

    (2013)
  • H.S. Jung

    Small

    (2015)
  • W.A. Dunlap-Shohl

    Chem. Rev.

    (2019)
  • J. Burschka

    Nature

    (2013)
  • J.-H. Im

    Nat. Nanotechnol.

    (2014)
  • Q. Chen

    J. Am. Chem. Soc.

    (2014)
  • B. Yang

    J. Am. Chem. Soc.

    (2015)
  • W.S. Yang

    Science

    (2015)
  • S. Das

    ACS Photonics

    (2015)
  • M. Saliba

    Energy Environ. Sci.

    (2016)
  • Research Cell Efficiency Records, NREL....
  • C. Wehrenfennig

    Energy Environ. Sci.

    (2014)
  • S.D. Stranks

    Science

    (2013)
  • G. Xing

    Science

    (2013)
  • C.-W. Chen

    Mater. Chem. A

    (2015)
  • Q. Lin

    Nat. Photonics

    (2014)
  • C. Wehrenfennig

    Adv. Mater.

    (2014)
  • S. Kazim

    Angew. Chem.

    (2014)
  • P. Gao

    Energy Environ. Sci.

    (2014)
  • S.D. Stranks

    Angew. Chem.

    (2015)
  • Y. Zhou

    J. Mater. Chem. A

    (2016)
  • A.M. Glazer

    Acta Crystallogr.

    (1972)
  • Q. Fu

    Adv. Sci.

    (2018)
  • C.C. Stoumpos

    Inorg. Chem.

    (2013)
  • A. Poglitsch

    J. Chem. Phys.

    (1987)
  • Y. Kawamura

    Phys. Soc. Jpn.

    (2002)
  • T. Baikie

    J. Mater. Chem. A

    (2013)
  • M.T. Weller

    Chem. Commun.

    (2015)
  • C.R. Kagan

    Science

    (1999)
  • J.W. Lee

    Adv. Mater.

    (2014)
  • T.M. Koh

    J. Phys. Chem. C

    (2014)
  • N. Pellet

    Angew. Chem.

    (2014)
  • J.W. Lee

    Adv. Energy Mater.

    (2015)
  • Z. Li

    Chem. Mater.

    (2016)
  • J.H. Noh

    Nano Lett.

    (2013)
  • Y. Chen

    Chem. Commun.

    (2015)
  • Q. Tai

    Nat. Commun.

    (2016)
  • M. Saliba

    Science

    (2016)
  • Z. Tang

    Sci. Rep.

    (2017)
  • D.Y. Son

    J. Am. Chem. Soc.

    (2018)
  • Y. Zhao

    J. Am. Chem. Soc.

    (2014)
  • Y. Zhou

    J. Phys. Chem. Lett.

    (2015)
  • A. Mei

    Science

    (2014)
  • Cited by (0)

    View full text