Publications by Paul Gratia | EPFL Graph Search

Nanoscale Mass-Spectrometry Imaging of Grain Boundaries in Perovskite Semiconductors

Mohammad Khaja Nazeeruddin, Paul Gratia, Tom Theodorus Antonius Lummen, Iwan Zimmermann, Hiroyuki Kanda

Incorporation of alkali metals such as Cs+, Rb+, and K+ into hybrid organic-inorganic halide lead perovskites (HOIPs) generally improves the optoelectronic properties of HOIPs. However, it is still uncertain how alkali metals interact and distribute within ...

2020

Improved efficiency and reduced hysteresis in ultra-stable fully printable mesoscopic perovskite solar cells through incorporation of CuSCN into the perovskite layer

Mohammad Khaja Nazeeruddin, Paul Gratia, Iwan Zimmermann, Giulia Grancini

Fully printable hole transport layer-free mesoscopic perovskite solar cells have proven excellent long-term stability and are therefore promising candidates for scale-up to larger modules required for the commercialization of the perovskite photovoltaic te ...

Royal Society of Chemistry2019

Diphenylamine-Substituted Carbazole-Based Hole Transporting Materials for Perovskite Solar Cells: Influence of Isomeric Derivatives

Mohammad Khaja Nazeeruddin, Paul Gratia, Kasparas Rakstys, Kyung Taek Cho, Sanghyun Paek

2018

Compositional Characterization of Organo-Lead tri-Halide Perovskite Solar Cells

Paul Gratia

Perovskite photovoltaics is one of the fastest growing research fields in materials science. Apart from photovoltaics, a wide range of energy-related research fields have gained substan-tial new momentum owing to the fantastic optoelectronic properties of ...

EPFL2018

Molecularly Engineered Phthalocyanines as Hole-Transporting Materials in Perovskite Solar Cells Reaching Power Conversion Efficiency of 17.5%

Mohammad Khaja Nazeeruddin, Paul Gratia, Peng Gao, Kyung Taek Cho, Cristina Roldán Carmona, Giulia Grancini, Olga Trukhina

Easily accessible tetra-5-hexylthiophene-, tetra-5-hexyl-2,2'-bisthiophene-substituted zinc phthalocyanines (ZnPcs) and tetra-tert-Bu ZnPc are employed as hole-transporting materials in mixed-ion perovskite [HC(NH2)2]0.85(CH3NH3)0.15Pb(I0.8 ...

2017

High-Efficiency Perovskite Solar Cells Using Molecularly Engineered, Thiophene-Rich, Hole-Transporting Materials: Influence of Alkyl Chain Length on Power Conversion Efficiency

Mohammad Khaja Nazeeruddin, Paul Gratia, Iwan Zimmermann, Giulia Grancini, Javier Urieta Mora

The synthesis and characterization of a series of novel small-molecule holetransporting materials (HTMs) based on an anthra [1,2-b: 4,3-b': 5,6-b '': 8,7-b '''] tetrathiophene (ATT) core are reported. The new compounds follow an easy synthetic route and ha ...

Wiley-V C H Verlag Gmbh2017

The Many Faces of Mixed Ion Perovskites: Unraveling and Understanding the Crystallization Process

Mohammad Khaja Nazeeruddin, Jun Ho Yum, Kevin Sivula, Paul Gratia, Iwan Zimmermann

Understanding the crystallization process of organic-inorganic halide perovskites is of paramount importance for fabrication of reproducible and efficient perovskite solar cells. We report for the first time on the discovery and interplay of ubiquitous hex ...

Amer Chemical Soc2017

Dopant-Free Hole-Transporting Materials for Stable and Efficient Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Christian Ludwig, Paul Gratia, Emad Oveisi, Peng Gao, Peng Qin, Kasparas Rakstys, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek

Molecularly engineered novel dopant-free hole-transporting materials for perovskite solar cells (PSCs) combined with mixed-perovskite (FAPbI(3))(0.85)(MAPbBr(3))(0.15) (MA: CH3NH3+, FA: NH=CHNH3+) that exhibit an excellent power conversion efficiency of 18 ...

Wiley-V C H Verlag Gmbh2017

Molecular engineering of face-on oriented dopant-free hole transporting material for perovskite solar cells with 19% PCE

Mohammad Khaja Nazeeruddin, Paul Gratia, Peng Gao, Kasparas Rakstys, Kyung Taek Cho, Sanghyun Paek, Giulia Grancini

Through judicious molecular engineering, novel dopant-free star-shaped D-pi-A type hole transporting materials coded KR355, KR321, and KR353 were systematically designed, synthesized and characterized. KR321 has been revealed to form a particular face-on o ...

Royal Society of Chemistry2017

Charge transporting material for optoelectronic and/or photoelectrochemical devices

Michael Graetzel, Mohammad Khaja Nazeeruddin, Paul Gratia, Iwan Zimmermann, Inés Garcia Benito

The present invention relates to an optoelectronic and/or photoelectrochemical device comprising at least one organic-inorganic perovskite as sensitizer and at least one compound of formula (I) comprising one benzotrithiophene core Q, wherein each thiophen ...

2017

High Open-Circuit Voltage: Fabrication of Formamidinium Lead Bromide Perovskite Solar Cells Using Fluorene-Dithiophene Derivatives as Hole-Transporting Materials

Michael Graetzel, Mohammad Khaja Nazeeruddin, Paul Gratia, Gwénolé Jean Jacopin, Mohammad Ibrahim Dar, Sadig Aghazada, Neha Arora, Filippo de Angelis

Four different fluorene dithiophene derivative-based hole-transporting materials (HTMs) (SO7-10) have been synthesized via a facile route and were successfully used in the fabrication of formamidinium lead bromide perovskite solar cells. Detailed character ...

Amer Chemical Soc2016

Branched methoxydiphenylamine-substituted fluorene derivatives as hole transporting materials for high-performance perovskite solar cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Paul Gratia, Taisuke Matsui, Michael Saliba, Simona Urnikaite

Small-molecule hole transporting materials based on methoxydiphenylamine-substituted fluorene fragments were synthesized and incorporated into a perovskite solar cell, which displayed a power conversion efficiency of up to 19.96%, one of the highest conver ...

Royal Soc Chemistry2016

A highly hindered bithiophene-functionalized dispiro-oxepine derivative as an efficient hole transporting material for perovskite solar cells

Mohammad Khaja Nazeeruddin, Paul Gratia, Peng Gao, Kasparas Rakstys, Yonghui Lee, Kyung Taek Cho, Sanghyun Paek, Muhammad Sohail

Dimethoxydiphenylamine-substituted dispiro-oxepine derivative 2,2',7,7'-tetrakis-(N,N'-di-4-methoxyphenylamine)dispiro-[fluorene-9,4'-dithieno(3,2-c:2',3'-e]oxepine-6',9 ''-fluorene] (DDOF) has been designed and synthesized using a facile synthetic route. ...

Royal Society of Chemistry2016

Benzotrithiophene-Based Hole-Transporting Materials for 18.2% Perovskite Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Paul Gratia, Sadig Aghazada, Cristina Roldán Carmona, Iwan Zimmermann, Inés Garcia Benito

New star-shaped benzotrithiophene (BTT)-based hole-transporting materials (HTM) BTT-1, BTT-2 and BTT-3 have been obtained through a facile synthetic route by crosslinking triarylamine-based donor groups with a benzotrithiophene (BTT) core. The BTT HTMs wer ...

Wiley-VCH Verlag GmbH2016

Intrinsic Halide Segregation at Nanometer Scale Determines the High Efficiency of Mixed Cation/Mixed Halide Perovskite Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Kevin Sivula, Xavier Adrian Jeanbourquin, Paul Gratia, Yonghui Lee, Iwan Zimmermann, Giulia Grancini, Filippo de Angelis

Compositional engineering of a mixed cation/mixed halide perovskite in the form of (FAP-bI(3))(0.85)(MAPbBr(3))(0.15) is one of the most effective strategies to obtain record-efficiency perovskite solar cells. However, the perovskite self-organization upon ...

2016

Enhanced TiO2/MAPbI(3) Electronic Coupling by Interface Modification with PbI2

Mohammad Khaja Nazeeruddin, Paul Gratia, Cristina Roldán Carmona, Iwan Zimmermann, Giulia Grancini, Filippo de Angelis

Amer Chemical Soc2016

Small molecule hole transporting material for optoelectronic and photoelectrochemical devices

Michael Graetzel, Mohammad Khaja Nazeeruddin, Paul Gratia

The present invention relates to a compound of formula (I) based on carbazole substituted by diphenylamine and used as organic hole conductors or hole transporting material in a optoelectronic or photoelectrochemical device. (I), D being being selected fro ...

2016

A Methoxydiphenylamine-Substituted Carbazole Twin Derivative: An Efficient Hole-Transporting Material for Perovskite Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Paul Gratia, Antonio Abate

The small-molecule-based hole-transporting material methoxydiphenylamine-substituted carbazole was synthesized and incorporated into a CH3NH3PbI3 perovskite solar cell, which displayed a power conversion efficiency of 16.91%, the second highest conversion ...

Wiley-VCH Verlag GmbH2015

High efficiency methylammonium lead triiodide perovskite solar cells: the relevance of non-stoichiometric precursors

Michael Graetzel, Mohammad Khaja Nazeeruddin, Paul Gratia, Peng Gao, Cristina Roldán Carmona, Iwan Zimmermann, Giulia Grancini

Methylammonium lead iodide perovskite solar cells with improved performance and stability have been successfully prepared by using a non-stoichiometric PbI2 : CH3NH3I ratio in the precursor solution, and yield a power conversion efficiency (PCE) of above 1 ...

Royal Soc Chemistry2015

Toward Higher Photovoltage: Effect of Blocking Layer on Cobalt Bipyridine Pyrazole Complexes as Redox Shuttle for Dye-Sensitized Solar Cells

Michael Graetzel, Jun Ho Yum, Paul Gratia, Aravind Kumar Chandiran, Thomas Moehl, Junghyun Yoon

Fluorine-doped tin-oxide (FTO) transparent conducting substrates, for use in cobalt bis(bipyridine pyrazole) complex based dye-sensitized solar cells (DSCs), were compared using the conventional TiCl4 treatment with conformal TiO2 blocking layers formed by ...

American Chemical Society2014