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Title: Large dielectric constant, high acceptor density, and deep electron traps in perovskite solar cell material CsGeI3

Journal Article · · Journal of Materials Chemistry. A
DOI:https://doi.org/10.1039/C6TA04685A· OSTI ID:1328304
 [1];  [2];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division and Center for Radiation Detection Materials and Systems
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division and Center for Radiation Detection Materials and Systems; Beihang Univ., Beijing (China). School of Physics and Nuclear Energy Engineering

Here we report that many metal halides that contain cations with the ns2 electronic configuration have recently been discovered as high-performance optoelectronic materials. In particular, solar cells based on lead halide perovskites have shown great promise as evidenced by the rapid increase of the power conversion efficiency. In this paper, we show density functional theory calculations of electronic structure and dielectric and defect properties of CsGeI3 (a lead-free halide perovskite material). The potential of CsGeI3 as a solar cell material is assessed based on its intrinsic properties. We find anomalously large Born effective charges and a large static dielectric constant dominated by lattice polarization, which should reduce carrier scattering, trapping, and recombination by screening charged defects and impurities. Defect calculations show that CsGeI3 is a p-type semiconductor and its hole density can be modified by varying the chemical potentials of the constituent elements. Despite the reduction of long-range Coulomb attraction by strong screening, the iodine vacancy in CsGeI3 is found to be a deep electron trap due to the short-range potential, i.e., strong Ge–Ge covalent bonding, which should limit electron transport efficiency in p-type CsGeI3. This is in contrast to the shallow iodine vacancies found in several Pb and Sn halide perovskites (e.g., CH3NH3PbI3, CH3NH3SnI3, and CsSnI3). The low-hole-density CsGeI3 may be a useful solar absorber material but the presence of the low-energy deep iodine vacancy may significantly reduce the open circuit voltage of the solar cell. Still, on the other hand, CsGeI3 may be used as an efficient hole transport material in solar cells due to its small hole effective mass, the absence of low-energy deep hole traps, and the favorable band offset with solar absorber materials such as dye molecules and CH3NH3PbI3.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1328304
Journal Information:
Journal of Materials Chemistry. A, Vol. 4, Issue 36; ISSN 2050-7488
Publisher:
Royal Society of ChemistryCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 113 works
Citation information provided by
Web of Science

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Cited By (23)

Solution‐Processable Perovskite Solar Cells toward Commercialization: Progress and Challenges journal April 2019
From Lead Halide Perovskites to Lead‐Free Metal Halide Perovskites and Perovskite Derivatives journal January 2019
Lead-Free Hybrid Perovskite Absorbers for Viable Application: Can We Eat the Cake and Have It too? journal November 2017
Progress in Theoretical Study of Metal Halide Perovskite Solar Cell Materials journal August 2017
Progress of Surface Science Studies on ABX 3 ‐Based Metal Halide Perovskite Solar Cells journal April 2020
Colloidal Quantum Nanostructures: Emerging Materials for Display Applications journal February 2018
Synthesis of Lead‐free CsGeI 3 Perovskite Colloidal Nanocrystals and Electron Beam‐induced Transformations journal May 2018
Bandgap Optimization of Perovskite Semiconductors for Photovoltaic Applications journal January 2018
Lead‐Free Semiconductors: Soft Chemistry, Dimensionality Control, and Manganese‐Doping of Germanium Halide Perovskites journal January 2019
On the Nitridation of Zn 2 GeO 4 journal February 2019
Effect of chemical nature of atoms on the electronic, dielectric, and dynamical properties of ABX 3 halide perovskite journal May 2020
Perovskite Solar Absorbers: Materials by Design journal March 2018
Inorganic Perovskite Solar Cells: A Rapidly Growing Field journal January 2018
Lead‐Free Tin‐Based Perovskite Solar Cells: Strategies Toward High Performance journal May 2019
Progress on lead-free metal halide perovskites for photovoltaic applications: a review journal March 2017
All-inorganic lead-free perovskites for optoelectronic applications journal January 2019
It's a trap! On the nature of localised states and charge trapping in lead halide perovskites journal January 2020
The influence of electrode for electroluminescence devices based on all-inorganic halide perovskite CsPbBr 3 journal November 2019
Optical and electronic properties of doped p -type CuI: Explanation of transparent conductivity from first principles journal March 2018
Perovskites-Based Solar Cells: A Review of Recent Progress, Materials and Processing Methods journal May 2018
Lead-free hybrid perovskites for photovoltaics journal January 2018
Optical and Electronic Properties of Doped $p$-type CuI: Explanation of Transparent Conductivity from First Principles text January 2018
Colloidal Quantum Nanostructures: Emerging Materials for Display Applications text January 2019

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