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Title: Polarization and Dielectric Study of Methylammonium Lead Iodide Thin Film to Reveal its Nonferroelectric Nature under Solar Cell Operating Conditions

Abstract

Researchers have debated whether methylammonium lead iodide (MAPbI3), with a perovskite crystal structure, is ferroelectric and therefore contributes to the current--voltage hysteresis commonly observed in hybrid perovskite solar cells (PSCs). We thoroughly investigated temperature-dependent polarization, dielectric, and impedance spectroscopies, and we found no evidence of ferroelectric effect in a MAPbI3 thin film at normal operating conditions. Therefore, the effect does not contribute to the hysteresis in PSCs, whereas the large component of ionic migration observed may play a critical role. Our temperature-based polarization and dielectric studies find that MAPbI3 exhibits different electrical behaviors below and above ca. 45 degrees C, suggesting a phase transition around this temperature. In particular, we report the activation energies of ionic migration for the two phases and temperature-dependent permittivity of MAPbI3. This study contributes to the understanding of the material properties and device performance of hybrid perovskites.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1273059
Report Number(s):
NREL/JA-5900-66340
Journal ID: ISSN 2380-8195
DOE Contract Number:
AC36-08GO28308
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Energy Letters; Journal Volume: 1; Journal Issue: 1
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; methylammonium lead iodide; temperature-dependent polarization; dielectric; impedance spectroscopies

Citation Formats

Hoque, Md Nadim Ferdous, Yang, Mengjin, Li, Zhen, Islam, Nazifah, Pan, Xuan, Zhu, Kai, and Fan, Zhaoyang. Polarization and Dielectric Study of Methylammonium Lead Iodide Thin Film to Reveal its Nonferroelectric Nature under Solar Cell Operating Conditions. United States: N. p., 2016. Web. doi:10.1021/acsenergylett.6b00093.
Hoque, Md Nadim Ferdous, Yang, Mengjin, Li, Zhen, Islam, Nazifah, Pan, Xuan, Zhu, Kai, & Fan, Zhaoyang. Polarization and Dielectric Study of Methylammonium Lead Iodide Thin Film to Reveal its Nonferroelectric Nature under Solar Cell Operating Conditions. United States. doi:10.1021/acsenergylett.6b00093.
Hoque, Md Nadim Ferdous, Yang, Mengjin, Li, Zhen, Islam, Nazifah, Pan, Xuan, Zhu, Kai, and Fan, Zhaoyang. 2016. "Polarization and Dielectric Study of Methylammonium Lead Iodide Thin Film to Reveal its Nonferroelectric Nature under Solar Cell Operating Conditions". United States. doi:10.1021/acsenergylett.6b00093.
@article{osti_1273059,
title = {Polarization and Dielectric Study of Methylammonium Lead Iodide Thin Film to Reveal its Nonferroelectric Nature under Solar Cell Operating Conditions},
author = {Hoque, Md Nadim Ferdous and Yang, Mengjin and Li, Zhen and Islam, Nazifah and Pan, Xuan and Zhu, Kai and Fan, Zhaoyang},
abstractNote = {Researchers have debated whether methylammonium lead iodide (MAPbI3), with a perovskite crystal structure, is ferroelectric and therefore contributes to the current--voltage hysteresis commonly observed in hybrid perovskite solar cells (PSCs). We thoroughly investigated temperature-dependent polarization, dielectric, and impedance spectroscopies, and we found no evidence of ferroelectric effect in a MAPbI3 thin film at normal operating conditions. Therefore, the effect does not contribute to the hysteresis in PSCs, whereas the large component of ionic migration observed may play a critical role. Our temperature-based polarization and dielectric studies find that MAPbI3 exhibits different electrical behaviors below and above ca. 45 degrees C, suggesting a phase transition around this temperature. In particular, we report the activation energies of ionic migration for the two phases and temperature-dependent permittivity of MAPbI3. This study contributes to the understanding of the material properties and device performance of hybrid perovskites.},
doi = {10.1021/acsenergylett.6b00093},
journal = {ACS Energy Letters},
number = 1,
volume = 1,
place = {United States},
year = 2016,
month = 7
}
  • Here, we report on the synthesis of methylammonium tin triiodide (MASnI 3) thin films at room temperature by a hybrid thermal evaporation method and their application in fabricating lead (Pb)-free perovskite solar cells. The as-deposited MASnI 3 thin films exhibit smooth surfaces, uniform coverage across the entire substrate, and strong crystallographic preferred orientation along the < 100 > direction. By incorporating this film with an inverted planar device architecture, our Pb-free perovskite solar cells are able to achieve an open-circuit voltage ( V oc) up to 494 mV. The relatively high V oc is mainly ascribed to the excellent surfacemore » coverage, the compact morphology, the good stoichiometry control of the MASnI 3 thin films, and the effective passivation of the electron-blocking and hole-blocking layers. Finally, our results demonstrate the potential capability of the hybrid evaporation method to prepare high-quality Pb-free MASnI 3 perovskite thin films which can be used to fabricate efficient Pb-free perovskite solar cells.« less
  • Cited by 1
  • Here, mixed tin (Sn) and lead (Pb) based perovskite thin films have been prepared by solution processing combining methylammonium lead iodide (MAPbI 3) and formamidinium tin iodide (FASnI 3) precursors. Optical response in the form of complex dielectric function (ε = ε 1 + iε 2) spectra and absorption coefficient (α) spectra of (FASnI 3) 1-x(MAPbI 3) x based perovskite films have been extracted over a spectral range 0.74 to 5.89 eV using spectroscopic ellipsometry. Absorption band edge energy changes as a function of composition for films including FASnI 3, MAPbI 3, and mixed x = 0.20, 0.35, 0.40, andmore » 0.6 (FASnI 3) 1-x(MAPbI 3) x perovskites. (FASnI 3) 0.60(MAPbI 3) 0.4 is found to have the minimum absorption band edge energy near ~1.2 eV.« less
  • Mixed tin (Sn)-lead (Pb) perovskites with high Sn content exhibit low bandgaps suitable for fabricating the bottom cell of perovskite-based tandem solar cells. In this work, we report on the fabrication of efficient mixed Sn-Pb perovskite solar cells using precursors combining formamidinium tin iodide (FASnI 3) and methylammonium lead iodide (MAPbI 3). The best-performing cell fabricated using a (FASnI 3) 0.6(MAPbI 3) 0.4 absorber with an absorption edge of ~1.2 eV achieved a power conversion efficiency (PCE) of 15.08 (15.00)% with an open-circuit voltage of 0.795 (0.799) V, a short-circuit current density of 26.86(26.82) mA/cm 2, and a fill factormore » of 70.6(70.0)% when measured under forward (reverse) voltage scan. In conclusion, the average PCE of 50 cells we have fabricated is 14.39 ± 0.33%, indicating good reproducibility.« less
  • We report a systematic study of the gigahertz-frequency charge carrier mobility found in methylammonium lead iodide perovskite films as a function of average grain size using time-resolved microwave conductivity and a single processing chemistry. Our measurements are in good agreement with the Kubo formula for the AC mobility of charges confined within finite grains, suggesting (1) that the surface grains imaged via scanning electron microscopy are representative of the true electronic domain size and not substantially subdivided by twinning or other defects not visible by microscopy and (2) that the time scale of diffusive transport across grain boundaries is muchmore » slower than the period of the microwave field in this measurement (-100 ps). The intrinsic (infinite grain size) minimum mobility extracted form the model is 29 +/- 6 cm2 V-1 s-1 at the probe frequency (8.9 GHz).« less