Elucidating the origins of subgap tail states and open-circuit voltage in methylammonium lead triiodide perovskite solar cells
File(s)
Published version
Author(s)
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.
Date Issued
2018-08-08
Date Acceptance
2018-04-29
Citation
Advanced Functional Materials, 2018, 28 (32), pp.1-11
ISSN
1616-301X
Publisher
Wiley
Start Page
1
End Page
11
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.
reproduction in any medium, provided the original work is properly cited.
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000440810500011&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
EP/M025020/1
EP/R020574/1
Subjects
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
Publication Status
Published
Article Number
1801808
Date Publish Online
2018-06-25