Publications de Ümmügülsüm Günes

Dopamine Dopes the Performance of Perovskite Solar Cells

Michael Graetzel, Mohammad Khaja Nazeeruddin, Paul Joseph Dyson, Shaik Mohammed Zakeeruddin, David Lyndon Emsley, Ursula Röthlisberger, Felix Thomas Eickemeyer, Lukas Pfeifer, Virginia Carnevali, Nikolaos Lempesis

The electron transport layer (ETL) is a crucial component of perovskite solar cells (PSCs) as it greatly influences their photovoltaic performance. Among various currently used ETL materials, SnO₂ stands out due to its unique advantages, including low‐temp ...

Wiley2025

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

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

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

Tuning 2D Perovskite Passivation: Impact of Electronic and Steric Effects on the Performance of 3D/2D Perovskite Solar Cells

Mohammad Khaja Nazeeruddin, Paul Joseph Dyson, Roland Christopher Turnell-Ritson, Ümmügülsüm Günes, Hiroyuki Kanda

Surface passivation with 2D perovskites is a powerful strategy to achieve improved stability and performance in perovskite solar cells (PSCs). Various large organic cations have been successfully implemented, led by phenylethylammonium (PEA+) and its deriv ...

WILEY-V C H VERLAG GMBH2023

Drastic influence of substituent position on orientation of 2D layers enables efficient and stable 3D/2D perovskite solar cells

Mohammad Khaja Nazeeruddin, Paul Joseph Dyson, Andreas Züttel, Ümmügülsüm Günes, Hiroyuki Kanda, Liping Zhong

The lack of long-term stability and reproducibility of perovskite solar cells (PSCs) is the main roadblock preventing their successful commercialization. 3D/2D PSCs are one of the most prominent ways to address these issues. Various salts that are mostly b ...

CELL PRESS2023