Pascal Alexander Schouwink

Related publications (20)

Mechanistic Study on Thermally Induced Lattice Stiffening of ZIF-8

Kumar Varoon Agrawal, Mehrdad Asgari, Deepu Joseph Babu, Jian Hao, Qi Liu, Wendy Lee Queen, Pascal Alexander Schouwink

The flexibility of the ZIF-8 aperture, which inhibits a molecular cutoff of 3.4 angstrom, can be reduced by rapid heat treatment to obtain CO2-selective membranes. However, the early stages of the structural, morphological, and chemical changes responsible for the lattice rigidification remain elusive. Herein, using ex situ and in situ experiments, we determine that a small shrinkage of the unit-cell parameter, similar to 0.2%, is mainly responsible for this transformation. Systematic gas permeation studies show that one needs to achieve this shrinkage without a disproportionately large shrinkage in the grain size of the polycrystalline film to avoid the formation of cracks. We show that this condition is uniquely achieved in a short time by exposure of ZIF-8 to a mildly humid environment where lattice parameter shrinkage is accelerated by the incorporation of linker vacancy defects, while the shrinkage in grain size is limited. The water-vapor-led incorporation of linker vacancy defects takes place with an energy barrier of 123 kJ mol(-1), much higher than that for the thermal degradation of ZIF-8,

2021

Methylammonium Triiodide for Defect Engineering of High-Efficiency Perovskite Solar Cells

Paramvir Ahlawat, Essa Awadh R Alharbi, Claudia Esther Avalos, Thomas Paul Baumeler, Mathias Dankl, Felix Thomas Eickemeyer, George Cameron Fish, Michael Graetzel, Ulf Anders Hagfeldt, Elsa John, Anurag Krishna, Mounir Driss Mensi, Jacques-Edouard Moser, Olivier Ouellette, Linfeng Pan, Lukas Pfeifer, Ursula Röthlisberger, Pascal Alexander Schouwink, Viktor Skorjanc, Bowen Yang, Shaik Mohammed Zakeeruddin

The defects present in metal halide perovskite are deleterious to both the performance and stability of photovoltaic devices. Consequently, there is an intense focus on developing defect mitigation strategies. Herein we report a facile strategy that employs methylammonium triiodide (MAI3) as an additive to the perovskite precursor solution. We examine the effect of MAI3 on the structural and optoelectronic properties by X-ray diffraction, density functional theory calculations, molecular dynamics simulations, solid-state nuclear magnetic resonance, steady-state, time-resolved photoluminescence (TRPL), and time-resolved terahertz spectroscopy (TRTS). Specifically, TRPL and TRTS show that MAI3 suppresses nonradiative recombination and increases the charge carrier mobility. As a result, the champion device shows a power conversion efficiency (PCE) of 23.46% with a high fill factor of >80%. Furthermore, these devices exhibit enhanced operational stability, with the best device retaining ∼90% of its initial PCE under 1 sun illumination with maximum power point tracking for 350 h.

2021

Naphthalenediimide/Formamidinium-Based Low-Dimensional Perovskites

Paramvir Ahlawat, Masaud Hassan S Almalki, Vincent Henri Guillaume Dufoulon, David Lyndon Emsley, George Cameron Fish, Michael Graetzel, Farzaneh Jahanbakhshi, Dominik Józef Kubicki, Jovana Milic, Aditya Mishra, Marko Mladenovic, Jacques-Edouard Moser, Ursula Röthlisberger, Marco Alejandro Ruiz Preciado, Thomas Schneeberger, Pascal Alexander Schouwink, Shaik Mohammed Zakeeruddin

Low-dimensional hybrid perovskites have emerged as promising materials for optoelectronic applications. Although these materials have already demonstrated enhanced stability as compared to their three-dimensional perovskite analogues, their functionality has been limited by the insulating character of the organic moieties that primarily play a structure-directing role. This is particularly the case for the layered (2D) perovskite materials based on formamidinium lead iodide (FAPbI3) that remain scarce. We demonstrate a low-dimensional hybrid perovskite material based on a SPbI4 composition incorporating an electroactive naphthalenediimide (NDI) moiety as an organic spacer (S) between the perovskite slabs and evidence the propensity of the spacer to stabilize the α-FAPbI3 perovskite phase in hybrid low-dimensional SFAn–1PbnI3n+1 perovskite compositions. This has been investigated by means of solid-state nuclear magnetic resonance spectroscopy in conjunction with molecular dynamics simulations and density functional theory calculations. Theoretical calculations suggest an electronic contribution of the organic spacer to the resulting optoelectronic properties, which was confirmed by transient absorption spectroscopy. We have further analyzed these materials by time-resolved microwave conductivity measurements, revealing challenges for their application in photovoltaics.

2021

Doped but Stable: Spirobisacridine Hole Transporting Materials for Hysteresis-Free and Stable Perovskite Solar Cells

Nikita Drigo, Marius Franckevicius, Hobeom Kim, Kun-Han Lin, Mohammad Khaja Nazeeruddin, Sanghyun Paek, Cristina Roldán Carmona, Pascal Alexander Schouwink, Muhammad Sohail, Albertus Adrian Sutanto

Four spirobisacridine (SBA) hole-transporting materials were synthesized and employed in perovskite solar cells (PSCs). The molecules bear electronically inert alkyl chains of different length and bulkiness, attached to in-plane N atoms of nearly orthogonal spiro-connected acridines. Di-p-methoxyphenylamine (DMPA) substituents tailored to the central SBA-platform define electronic properties of the materials mimicking the structure of the benchmark 2,2',7,7'-tetrakis(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (spiro-MeOTAD), while the alkyl pending groups affect molecular packing in thin films and affect the long-term performance of PSCs. Devices with SBA-based hole transporting layers (HTL) attain efficiencies on par with spiro-MeOTAD. More importantly, solar cells with the new HTMs are hysteresis-free and demonstrate good operational stability, despite being doped as spiro-MeOTAD. The best performing MeSBA-DMPA retained 88% of the initial efficiency after a 1000 h aging test under constant illumination. The results clearly demonstrate that SBA-based compounds are potent candidates for a design of new HTMs for PSCs with improved longevity.

AMER CHEMICAL SOC2020

Dynamical evolution of the 2D/3D interface: a hidden driver behind perovskite solar cell instability

Kyung Taek Cho, Nikita Drigo, Inés Garcia Benito, Giulia Grancini, Mohammad Khaja Nazeeruddin, Sanghyun Paek, Valentin Ianis Emmanuel Queloz, Pascal Alexander Schouwink, Albertus Adrian Sutanto

Engineering two-/three-dimensional (2D/3D) perovskite solar cells is nowadays a popular strategy for efficient and stable devices. However, the exact function of the 2D/3D interface in controlling the long-term device behavior is still obscure. Here, we reveal a dynamical structural mutation of the 2D/3D interface: the small cations in the 3D cage move towards the 2D layer, which acts as an ion scavenger. If structurally stable, the 2D layer physically blocks the ion movement at the interface boosting the device stability. Otherwise, the 2D layer embeds them, dynamically self-transforming into a quasi-2D structure. The judicious choice of the 2D constituent is decisive in controlling the 2D/3D kinetics and improving the device lifetime, opening a new avenue for perovskite interface design.

2020

Efficient Hydrogen Oxidation Catalyzed by Strain-Engineered Nickel Nanoparticles

Xile Hu, Weiyan Ni, Pascal Alexander Schouwink, Teng Wang

The hydroxide-exchange membrane fuel cell (HEMFC) is a promising energy conversion device. However, the development of HEMFC is hampered by the lack of platinum-group-metal-free (PGM-free) electrocatalysts for the hydrogen oxidation reaction (HOR). Now, a Ni catalyst is reported that exhibits the highest mass activity in HOR for a PGM-free catalyst as well as excellent activity in the hydrogen evolution reaction (HER). This catalyst, Ni-H-2-2 %, was optimized through pyrolysis of a Ni-containing metal-organic framework precursor under a mixed N-2/H-2 atmosphere, which yielded carbon-supported Ni nanoparticles with different levels of strains. The Ni-H-2-2 % catalyst has an optimal level of strain, which leads to an optimal hydrogen binding energy and a high number of active sites.

WILEY-V C H VERLAG GMBH2020

Essential role of oxygen vacancies of Cu-Al and Co-Al spinel oxides in their catalytic activity for the reverse water gas shift reaction

Alimohammad Bahmanpour, Christophe Jean Baranowski, Florent Emmanuel Héroguel, Murat Kiliç, Oliver Kröcher, Jeremy Luterbacher, Ursula Röthlisberger, Pascal Alexander Schouwink

CO2 catalytic hydrogenation to CO will likely be an important part of CO2 mitigation and valorization processes. Recently, we have developed materials containing surface-formed Cu-Al spinel that act as active and stable catalysts for this reaction. Here, the fundamental characteristics of Cu-Al and Co-Al spinel catalysts were studied to understand the role of the spinel structure in its catalytic activity for the reverse water gas shift reaction. Based on the catalytic tests, Cu-Al spinel was found to have a higher catalytic activity. By means of catalysts characterization combined with theoretical studies, this increased activity was attributed to the higher number of oxygen vacancies on its surface which were formed because of the higher inversion degree of Cu-Al spinel, which in turn, resulted in the formation of a more disordered structure with cation substitution. We found that the oxygen vacancies were vital for CO2 adsorption and activation on the spinel surfaces.

2020

Incorporation of Clathrochelate-Based Metalloligands in Metal-Organic Frameworks by Solvent-Assisted Ligand Exchange

José Luis Bila, Farzaneh Fadaei Tirani, Ophélie Marie Planes, Pascal Alexander Schouwink, Rosario Scopelliti, Kay Severin

Iron(II) cage complexes with terminal 4-pyridyl groups can be incorporated in metal-organic frameworks (MOFs) via solvent-assisted ligand exchange (SALE). Paddle -wheeled MOFs with N,N'-di-4-pyridylnaphthalenete-tracarboxydiimide pillars were used as starting materials. Pillar exchange was nearly quantitative, despite the fact that the cage complexes are long (similar to 15 angstrom) and sterically demanding. The reactions provide products of high crystallinity, and the structures of daughter MOFs were determined by single crystal X-ray diffraction. The crystallographic analyses showed that some of the SALE experiments led to topological changes of the MOF structures.

AMER CHEMICAL SOC2020

Molecular Design and Operational Stability: Toward Stable 3D/2D Perovskite Interlayers

Kyung Taek Cho, Nikita Drigo, Marius Franckevicius, Hiroyuki Kanda, Hobeom Kim, Kun-Han Lin, Mohammad Khaja Nazeeruddin, Sanghyun Paek, Cristina Roldán Carmona, Pascal Alexander Schouwink

Despite organic/inorganic lead halide perovskite solar cells becoming one of the most promising next-generation photovoltaic materials, instability under heat and light soaking remains unsolved. In this work, a highly hydrophobic cation, perfluorobenzylammonium iodide (5FBzAI), is designed and a 2D perovskite with reinforced intermolecular interactions is engineered, providing improved passivation at the interface that reduces charge recombination and enhances cell stability compared with benchmark 2D systems. Motivated by the strong halogen bond interaction, (5FBzAI)(2)PbI(4)used as a capping layer aligns in in-plane crystal orientation, inducing a reproducible increase of approximate to 60 mV in theV(oc), a twofold improvement compared with its analogous monofluorinated phenylethylammonium iodide (PEAI) recently reported. This endows the system with high power conversion efficiency of 21.65% and extended operational stability after 1100 h of continuous illumination, outlining directions for future work.

2020

Understanding How Ligand Functionalization Influences CO2 and N-2 Adsorption in a Sodalite Metal-Organic Framework

Mehrdad Asgari, Michele Ceriotti, Ilia Kochetygov, Wendy Lee Queen, Pascal Alexander Schouwink, Rocio Semino Barbaresi, Olga Trukhina

In this work, a detailed study is conducted to understand how ligand substitution influences the CO, and N-2 adsorption properties of two highly crystalline sodalite metal-organic frameworks (MOFs) known as Cu-BTT (BTT-3 = 1,3,5-benzenetristetrazolate) and Cu-BTTri (BTTri(-3) = 1,3,5-benzenetristriazolate). The enthalpy of adsorption and observed adsorption capacities at a given pressure are significantly lower for Cu-BTTri compared to its tetrazole counterpart, Cu-BTT. In situ X-ray and neutron diffraction, which allow visualization of the CO2 and N-2 binding sites on the internal surface of Cu-BTTri, provide insights into understanding the subtle differences. As expected, slightly elongated distances between the open Cu2+ sites and surface-bound CO, in Cu-BTTri can be explained by the fact that the triazolate ligand is a better electron donor than the tetrazolate. The more pronounced Jahn-Teller effect in Cu-BTTri leads to weaker guest binding. The results of the aforementioned structural analysis were complemented by the prediction of the binding energies at each CO2 and N-2 adsorption site by density functional theory calculations. In addition, variable temperature in situ diffraction measurements shed light on the fine structural changes of the framework and CO2 occupancies at different adsorption sites as a function of temperature. Finally, simulated breakthrough curves obtained for both sodalite MOFs demonstrate the materials' potential performance in dry postcombustion CO2 capture. The simulation, which considers both framework uptake capacity and selectivity, predicts better separation performance for Cu-BTT. The information obtained in this work highlights how ligand substitution can influence adsorption properties and hence provides further insights into the material optimization for important separations.

AMER CHEMICAL SOC2020