1. Perovskite Solar Cells and Devices at EPFL Valais Wallis
Mohammad Khaja Nazeeruddin*[a]
The world global installed photovoltaic (PV) capacity is ex-
pected to reach well over 1000 GW by 2030 and could reach
up to 5000 GW by 2050. At this moment, solar energy will
likely be one of the major electricity sources worldwide, with
the lowest costs and environmental impact, while contributing
to mitigating CO2 gas emissions. New PV technologies with
higher potential performances at lower price will lead this
paradigm shift. In this context, the World Economic Forum has
recently recognized perovskite solar cells (PSCs) as one of the
top 10 technologies in 2016. Indeed, PSCs have emerged as
one of the most exciting fields of research of our time, for
their impressive rise in power conversion efficiency (PCE) sur-
passing 22% in six short years of research. PSCs are leading
a real revolution in power generation, standing over the main
technologies on the market.[1–3]
The Group for Molecular Engineering of Functional Materials
(GMF) at EPFL has earned worldwide recognition and leader-
ship in the PSC research field, as testified by the impressive
track record that counts more than 100 ground-breaking publi-
cations in the field and 15 patents filed. With pioneer works on
the development of highly efficient hybrid PSCs through care-
ful control of the material engineering, optimization of the fab-
rication protocols, and in-depth understanding of the device
operation, the group is contributing significantly in the ad-
vancement of this new technology. At present, the mission of
the group, characterized by a strong interdisciplinary character,
embraces multiple directions devoted to the realization of
highly efficient, stable, and not toxic PSCs, enabling a real
uptake of this technology in the market. This includes the
design of novel multi-dimensional perovskite materials with
a reduced lead content, synthesis of new low-cost dopant-free
hole-transporting materials (HTMs), engineering of new device
architectures, as well as deep fundamental investigations on
the photophysical mechanisms governing device operation.
More specifically, device engineers within GMF are focused
on developing solution-processable methods to improve the
device open circuit voltage (VOC), without sacrificing short-
circuit current density (JSC), by introducing specific surface pas-
sivation layers; recently, a PCE of 21.3% was reached within
the scope of this project. In parallel, high-vacuum sublimation
techniques are also used to grow high-quality films and
tandem layered structures with extreme control of crystal
growth and composition. The synthetic chemists are focused
mainly on the design of low-cost HTMs (i.e., phthalocyanines,
elementary inorganic compounds, or dopant-free HTMs) to
boost the solar cell stability at a reduced price by eliminating
the need for commonly used, expensive, and relatively unsta-
ble doped spiro-OMeTAD layers (Figure 1). The material devel-
opment also includes inorganic compounds for applications
beyond PV, such as light-emitting diodes. Last, but not least,
the group’s research activity is also focused on unveiling the
Mohammad Khaja Nazeeruddin is
a Professor at the École polytechnique
fØdØrale de Lausanne, and directs the
Group for Molecular Engineering of
Functional Materials (http://
gmf.epfl.ch/) at EPFL Valais Wallis
based in Sion, Switzerland. The highly
multidisciplinary group consists of
a number of postdoctoral researchers
and senior scientists, including Dr.
Aron Joel Huckaba (Ph.D. Chemistry,
University of Mississippi, USA), Dr. Cris-
tina Roldµn Carmona (Ph.D. Chemistry Science, Córdoba National
University/Valencia University, Spain), Dr. Giulia Grancini (Ph.D.
Physics, Politecnico of Milano, Italy), Dr. Iwan Zimmermann (Ph.D.
Inorganic Chemistry, Stockholm University, Sweden), Dr. Peng Gao
(Ph.D. Chemistry, Johannes Gutenberg University of Mainz, Germa-
ny), Dr. Sanghyun Paek (Ph.D. Materials Chemistry, Korea University,
Korea), Dr. Yonghui Lee (Ph.D. Materials Science and Engineering,
Korea University, Korea), as well as graduate students. He is an
expert in dye-sensitized solar cells, perovskite solar cells, and or-
ganic light-emitting diodes, and has published over 500 peer-
reviewed scientific publications, 12 review articles/invited book
chapters, and is inventor or co-inventor of over 50 patents with an
H-index of 111 (total number of citations over 55000). Furthermore,
he is one of the 19 scientists identified by Thomson Reuters as the
World’s Most Influential Scientific Minds from all scientific domains,
and appeared in the 2014, 2015, and 2016 Lists of Most Cited Re-
searchers in the field of materials science and engineering. He has
been appointed as a world-class university professor at Korea Uni-
versity, Korea, Eminent Professor at the University Brunei Darussa-
lam, Brunei, and Distinguished Professor at King Abdulaziz Univer-
sity, Jeddah. For ChemPubSoc Europe, he is a board member of
the journal ChemSusChem.
[a] Prof. M. K. Nazeeruddin
Group for Molecular Engineering of Functional Materials
EPFL Valais Wallis
Rue de l’Industrie 17, 1951 Sion (Switzerland)
E-mail: mdkhaja.nazeeruddin@epfl.ch
Homepage: http://gmf.epfl.ch/
This publication is part of a Special Issue focusing on the “Stability of
Perovskite Solar Cells & Devices”. A link to the issue’s Table of Contents
will appear here once it is complete.
ChemSusChem 2016, 9, 1 – 3 2016 Wiley-VCH Verlag GmbH Co. KGaA, Weinheim1
These are not the final page numbers! ÞÞThese are not the final page numbers! ÞÞ
EditorialDOI: 10.1002/cssc.201601197

2. fundamental structural, optical, and photophysical properties
of PSCs. This includes the analysis of the main photoinduced
processes from femtosecond to nanosecond time scales (i.e.,
exciton and charge dynamics, charge transport, recombination,
and trapping), of utmost importance to set the guidelines for
rational device design and optimization.
We envisage that the Group for Molecular Engineering of
Functional Materials will contribute to the realization of high-
performance, non-toxic perovskite materials and solar cells
with a significant advance in device stability beyond the state-
of-the-art, enabling a secure and environmentally friendly low-
cost near-future PV technology. It is a pleasure to write the edi-
torial for this special issue of ChemSusChem, which addresses
the core concern (i.e., stability) of perovskite materials and de-
vices.
Keywords: materials science · photophysical properties ·
perovskite · solar cells · stability
[1] National Renewable Energy Laboratory Best Research-Cell Efficiencies
Chart, http://www.nrel.gov/ncpv/images/efficiency_chart.jpg, 2016.
[2] M. Saliba, S. Orlandi, T. Matsui, S. Aghazada, M. Cavazzini, J.-P. Correa-
Baena, P. Gao, R. Scopelliti, E. Mosconi, K.-H. Dahmen, F. De Angelis, A.
Abate, A. Hagfeldt, G. Pozzi, M. Grätzel, M K. Nazeeruddin, Nature Energy,
2016, 1, 15017.
[3] M. Saliba, T. Matsui, J.-Y. Seo, K. Domanski, J.-P. Correa-Baena, M. K. Na-
zeeruddin, S. M. Zakeeruddin, W. Tress, A. Abate, A. Hagfeldt, M. Grätzel,
Energy Environ. Sci., 2016, 9, 1989–1997.
Figure 1. Perovskite solar cells of the GMF. (a) Photographs of mesoscopic- and planar-type PSCs. (b) Schematic showing charge transfer in PSCs. (c) Current–
voltage curve of a mesoporous TiO2-based PSC with poly(triarylamine) (PTAA) as the HTM. (d) Scanning electron microscopy cross-sectional image of a meso-
porous TiO2-based PSC.
ChemSusChem 2016, 9, 1 – 3 www.chemsuschem.org 2016 Wiley-VCH Verlag GmbH Co. KGaA, Weinheim2
ÝÝ These are not the final page numbers!ÝÝ These are not the final page numbers!
Editorial

3. EDITORIAL
M. K. Nazeeruddin*
–
Perovskite Solar Cells and Devices at
EPFL Valais Wallis
Stability required! Perovskite solar cells
have emerged as one of the most excit-
ing fields of research, owing to their im-
pressive rise in power conversion effi-
ciency surpassing 22% in six short years
of research. Current research is focused
on ways to improve stability of perov-
skite-based devices, a key characteristic
required to bring this technology from
the lab into the market. In this Editorial,
guest editor Prof. Mohammad Khaja Na-
zeeruddin describes the context of this
Special Issue, and summarizes the work
being performed in his research group
toward this low-cost near-future photo-
voltaic technology.
ChemSusChem 2016, 9, 1 – 3 www.chemsuschem.org 2016 Wiley-VCH Verlag GmbH Co. KGaA, Weinheim3
These are not the final page numbers! ÞÞThese are not the final page numbers! ÞÞ