Indirect to direct bandgap transition in methylammonium lead halide perovskite
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Methylammonium lead iodide perovskites are considered direct bandgap semiconductors. Here we show that in fact they present a weakly indirect bandgap 60 meV below the direct bandgap transition. This is a consequence of spin-orbit coupling resulting in Rashba-splitting of the conduction band. The indirect nature of the bandgap explains the apparent contradiction of strong absorption and long charge carrier lifetime. Under hydrostatic pressure from ambient to 325 MPa, Rashba splitting is reduced due to a pressure induced ordering of the crystal structure. The nature of the bandgap becomes increasingly more direct, resulting in five times faster charge carrier recombination, and a doubling of the radiative efficiency. At hydrostatic pressures above 325 MPa, MAPI undergoes a reversible phase transition resulting in a purely direct bandgap semiconductor. The pressure-induced changes suggest epitaxial and synthetic routes to higher efficiency optoelectronic devices.
Date Issued
2016-12-09
Date Acceptance
2016-12-09
Citation
Energy & Environmental Science, 2016, 10, pp.509-515
ISSN
1754-5706
Publisher
Royal Society of Chemistry
Start Page
509
End Page
515
Journal / Book Title
Energy & Environmental Science
Volume
10
Copyright Statement
This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
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Subjects
Science & Technology
Physical Sciences
Technology
Life Sciences & Biomedicine
Chemistry, Multidisciplinary
Energy & Fuels
Engineering, Chemical
Environmental Sciences
Chemistry
Engineering
Environmental Sciences & Ecology
HETEROJUNCTION SOLAR-CELLS
OPTICAL-PROPERTIES
IODIDE PEROVSKITE
CARRIER-LIFETIME
SINGLE-CRYSTALS
CH3NH3PBI3
EFFICIENCY
GAP
PHOTOLUMINESCENCE
MICROSTRUCTURE
cond-mat.mtrl-sci
MD Multidisciplinary
Energy
Publication Status
Published