Publications de Michael Allan Hope

Strain-induced rubidium incorporation into wide-bandgap perovskites reduces photovoltage loss

Michael Graetzel, Shaik Mohammed Zakeeruddin, David Lyndon Emsley, Ursula Röthlisberger, Mounir Driss Mensi, Felix Thomas Eickemeyer, Pascal Alexander Schouwink, Lukas Pfeifer, Jing Gao, Virginia Carnevali

A-site cation mixing can enhance the photovoltaic performance of a wide-bandgap (WBG) perovskite, but rubidium (Rb) cation mixing generally forms a nonperovskite phase. We report that lattice strain locks Rb ions into the α-phase of the lattice of a triple ...

American Association for the Advancement of Science (AAAS)2025

Magic Angle Spinning Solid-State 13C Photochemically Induced Dynamic Nuclear Polarization by a Synthetic Donor-Chromophore-Acceptor System at 9.4 T

David Lyndon Emsley, Federico De Biasi, Máté Visegrádi, Michael Allan Hope

Solid-state photochemically induced dynamic nuclear polarization (photo-CIDNP) is a nuclear magnetic resonance spectroscopy technique in which nuclear spin hyperpolarization is generated upon optical irradiation of an appropriate donor-acceptor system. Unt ...

Amer Chemical Soc2024

Stabilization of highly efficient perovskite solar cells with a tailored supramolecular interface

Michael Graetzel, Shaik Mohammed Zakeeruddin, David Lyndon Emsley, Felix Thomas Eickemeyer, Chenxu Zhao, Michael Allan Hope, Aditya Mishra, Masaud Hassan S Almalki, Anurag Krishna, Zhiwen Zhou

The presence of defects at the interface between the perovskite film and the carrier transport layer poses significant challenges to the performance and stability of perovskite solar cells (PSCs). Addressing this issue, we introduce a dual host-guest (DHG) ...

Nature Research2024

Axial-Equatorial Halide Ordering in Layered Hybrid Perovskites from Isotropic-Anisotropic 207Pb NMR

David Lyndon Emsley, Ümmügülsüm Günes, Michael Allan Hope, Manuel Cordova, Aditya Mishra

Bandgap-tuneable mixed-halide 3D perovskites are of interest for multi-junction solar cells, but suffer from photoinduced spatial halide segregation. Mixed-halide 2D perovskites are more resistant to halide segregation and are promising coatings for 3D per ...

Wiley-VCH Verlag GmbH2024

Light-Induced Metallic and Paramagnetic Defects in Halide Perovskites from Magnetic Resonance

David Lyndon Emsley, Michael Allan Hope, Aditya Mishra

Halide perovskites are promising next-generation solar cell materials, but their commercialization is hampered by their propensity to degrade under operating conditions, particularly under heat, humidity, and light. Identifying degradation products and lin ...

2024

Probing structural and dynamic properties of MAPbCl3 hybrid perovskite using Mn2+ EPR

Michael Allan Hope, Yuxuan Zhang

Hybrid methylammonium (MA) lead halide perovskites have emerged as materials exhibiting excellent photovoltaic performance related to their rich structural and dynamic properties. Here, we use multifrequency (X-, Q-, and W-band) electron paramagnetic reson ...

Royal Soc Chemistry2024

Light-Induced 1H NMR Hyperpolarization in Solids at 9.4 and 21.1 T

David Lyndon Emsley, Federico De Biasi, Máté Visegrádi, Michael Allan Hope

The inherently low sensitivity of nuclear magnetic resonance (NMR) spectroscopy is the major limiting factor for its application to elucidate structure and dynamics in solids. In the solid state, nuclear spin hyperpolarization methods based on microwave-in ...

2024

Formamidinium Incorporates into Rb-based Non-Perovskite Phases in Solar Cell Formulations

Michael Graetzel, David Lyndon Emsley, Lukas Pfeifer, Likai Zheng, Ümmügülsüm Günes, Michael Allan Hope, Yuxuan Zhang

Organic-inorganic hybrid perovskite materials, such as formamidinium lead iodide (FAPbI3), are among the most promising emerging photovoltaic materials. However, the spontaneous phase transition from the photoactive perovskite phase to an inactive non-pero ...

Wiley-VCH Verlag GmbH2024

Dynamic nuclear polarisation of 1H in Gd-doped In(OH)3

David Lyndon Emsley, Michael Allan Hope, Amrit Venkatesh, Yuxuan Zhang

Dynamic nuclear polarisation (DNP) of solids doped with high-spin metal ions, such as Gd3+, is a useful strategy to enhance the nuclear magnetic resonance (NMR) sensitivity for these samples. Spin diffusion can relay polarisation throughout a sample, which ...

Academic Press Inc - Elsevier Science2023

Light-Induced Halide Segregation in 2D and Quasi-2D Mixed-Halide Perovskites

David Lyndon Emsley, Manuel Cordova, Michael Allan Hope, Aditya Mishra

Photoinduced halide segregation hinders widespread application of three-dimensional (3D) mixed-halide perovskites. Much less is known about this phenomenon in lower-dimensional systems. Here, we study photoinduced halide segregation in lower-dimensional mi ...

AMER CHEMICAL SOC2023