Elucidating the origins of subgap tail states and open-circuit voltage in methylammonium lead triiodide perovskite solar cells

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Title: Elucidating the origins of subgap tail states and open-circuit voltage in methylammonium lead triiodide perovskite solar cells
Authors: Du, T
Kim, J
Ngiam, J
Xu, S
Barnes, PRF
Durrant, JR
McLachlan, MA
Item Type: Journal Article
Abstract: Recombination via subgap trap states is considered a limiting factor in the development of organometal halide perovskite solar cells. Here, the impact of active layer crystallinity on the accumulated charge and open‐circuit voltage (Voc) in solar cells based on methylammonium lead triiodide (CH3NH3PbI3, MAPI) is demonstrated. It is shown that MAPI crystallinity can be systematically tailored by modulating the stoichiometry of the precursor mix, where small quantities of excess methylammonium iodide (MAI) improve crystallinity, increasing device Voc by ≈200 mV. Using in situ differential charging and transient photovoltage measurements, charge density and charge carrier recombination lifetime are determined under operational conditions. Increased Voc is correlated to improved active layer crystallinity and a reduction in the density of trap states in MAPI. Photoluminescence spectroscopy shows that an increase in trap state density correlates with faster carrier trapping and more nonradiative recombination pathways. Fundamental insights into the origin of Voc in perovskite photovoltaics are provided and it is demonstrated why highly crystalline perovskite films are paramount for high‐performance devices.
Issue Date: 8-Aug-2018
Date of Acceptance: 29-Apr-2018
URI: http://hdl.handle.net/10044/1/64346
DOI: https://dx.doi.org/10.1002/adfm.201801808
ISSN: 1616-301X
Publisher: Wiley
Journal / Book Title: Advanced Functional Materials
Volume: 28
Issue: 32
Copyright Statement: © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. This is an open access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords: Science & Technology
Physical Sciences
Technology
Chemistry, Multidisciplinary
Chemistry, Physical
Nanoscience & Nanotechnology
Materials Science, Multidisciplinary
Physics, Applied
Physics, Condensed Matter
Chemistry
Science & Technology - Other Topics
Materials Science
Physics
crystallinity
open-circuit voltage
perovskite solar cells
tail states
NONRADIATIVE RECOMBINATION
HALIDE PEROVSKITES
THIN-FILMS
CH3NH3PBI3
HYSTERESIS
EVOLUTION
LOSSES
MICROSTRUCTURE
LIFETIMES
KINETICS
03 Chemical Sciences
09 Engineering
02 Physical Sciences
Materials
Publication Status: Published
Open Access location: https://onlinelibrary.wiley.com/doi/full/10.1002/adfm.201801808
Article Number: 1801808
Online Publication Date: 2018-06-25
Appears in Collections:Materials
Physics
Chemistry
Experimental Solid State
Faculty of Natural Sciences



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