Publications by Likai Zheng | EPFL Graph Search

Spiro-Phenothiazine Hole-Transporting Materials: Unlocking Stability and Scalability in Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Jaeki Jeong, Likai Zheng

Improving both the efficiency and long-term stability of perovskite solar cells (PSCs) is critical for their commercial deployment. Despite the widespread use of spiro-OMeTAD as a hole-transporting material (HTM), its inhomogeneous doping behavior and susc ...

2025

Unraveling the Role of Electron-Withdrawing Molecules for Highly Efficient and Stable Perovskite Photovoltaics

Michael Graetzel, Shaik Mohammed Zakeeruddin, Mingyang Wei, Likai Zheng

Electron-withdrawing molecules (EWMs) have exhibited remarkable efficacy in boosting the performance of perovskite solar cells (PSCs). However, the underneath mechanisms governing their positive attributes remain inadequately understood. Herein, we conduct ...

Wiley-VCH Verlag GmbH2025

Realizing Uniform Defect Passivation via Self‐Polymerization of Benzenesulfonate Molecules in Perovskite Photovoltaics

Michael Graetzel, Mingyang Wei, Likai Zheng, Xiaoqing Jiang

Realizing high‐quality perovskite films through uniform defect passivation and crystallization control is pivotal to unlocking the potential of scalable applications. However, prevalent small‐molecule additives are inherently susceptible to the crystalliza ...

Wiley2025

Suppressing wide-angle light loss and non-radiative recombination for efficient perovskite solar cells

Michael Graetzel, Jing Gao, Likai Zheng

Surface reflections and non-radiative recombinations create energy losses in perovskite solar cells (PSCs) by hindering the generation and extraction of carriers. These losses can reduce device efficiency in practical applications as the incident angle of ...

Nature Publishing Group2025

Dissolvable molecular bridges promoting buried interface modification for high-performance inverted perovskite solar cells

Likai Zheng

Non-radiative recombination and suboptimal interfacial contact at the hole transportation layer (HTL)/perovskite interface critically suppress the device performance and stability of inverted perovskite solar cells (PSCs). Herein, we proposed a dissolvable ...

2025

Low-temperature thermite reaction to form oxygen vacancies in metal-oxide semiconductors: A case study of photoelectrochemical cells

Michael Graetzel, Kevin Sivula, Likai Zheng

The formation of oxygen vacancies (Vö) in n-type semiconductors is a key strategy for improving the performance of metal-oxide-based photoanodes. Whereas Vö has traditionally been created by gas- or liquid-phase treatments, here we report a solid-state red ...

2025

Dopamine Dopes the Performance of Perovskite Solar Cells

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

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, Mounir Driss Mensi, Ursula Röthlisberger, David Lyndon Emsley, Pascal Alexander Schouwink, Jing Gao, Felix Thomas Eickemeyer, Michael Allan Hope, Lukas Pfeifer, Nikolaos Lempesis, Virginia Carnevali, Ümmügülsüm Günes, Lorenzo Agosta, Yuxuan Zhang, Likai Zheng

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

Dipolar Carbazole Ammonium for Broadened Electric Field Distribution in High-Performance Perovskite Solar Cells

Felix Thomas Eickemeyer, Jaeki Jeong, Likai Zheng

Perovskite solar cells (PSCs) with ammonium passivation exhibit superior device performance and stability. Beyond typical chemical passivation, ammonium salts control the electronic structure of perovskite surfaces, yet the molecular structure-property rel ...

2025

All-SnO2-Based Conformal Electron Transport Layer for Efficient Perovskite Solar Cells

Likai Zheng

The fabrication of high-performance perovskite solar cells on high-haze fluorine-doped tin oxide (FTO) substrates with superior light-trapping capabilities necessitates a highly conformal electron transport layer at the bottom interface. Herein, a conforma ...

2024

Tailored Supramolecular Interactions in Host–Guest Complexation for Efficient and Stable Perovskite Solar Cells and Modules

Michael Graetzel, Shaik Mohammed Zakeeruddin, Mingyang Wei, Likai Zheng

Host-guest complexation offers a promising approach for mitigating surface defects in perovskite solar cells (PSCs). Crown ethers are the most widely used macrocyclic hosts for complexing perovskite surfaces, yet their supramolecular interactions and funct ...

Wiley-VCH Verlag GmbH2024

Influence of F-Containing Materials on Perovskite Solar Cells

Likai Zheng

Perovskite solar cells (PSCs) are usually modified and passivated to improve their performance and stability. The interface modification and bulk doping are the two basic strategies. Fluorine (F)-containing materials are highly favored because of their uni ...

2024

Spatial Conformation Engineering of Aromatic Ketones for Highly Efficient and Stable Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Likai Zheng, Xiaoqing Jiang

Carbonyl-containing materials employed in state-of-the-art hybrid lead halide perovskite solar cells (PSCs) exhibit a strong structure-dependent electron donor effect that predominates in defect passivation. However, the impact of the molecular spatial con ...

AMER CHEMICAL SOC2024

Insights Into the Role of π-Electrons of Aromatic Aldehydes in Passivating Perovskite Defects

Likai Zheng

Carbonyl-containing aromatic ketones or aldehydes have been demonstrated to be effective defect passivators for perovskite films to improve performances of perovskite solar cells (PSCs). It has been claimed that both π-electrons within aromatic units and c ...

Wiley-VCH Verlag GmbH2024

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

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

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

Vapor-assisted deposition of highly efficient, stable black-phase FAPbI(3) perovskite solar cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ursula Röthlisberger, Ulf Anders Hagfeldt, Xiong Li, Wolfgang Richard Tress, David Lyndon Emsley, Paramvir Ahlawat, Claudia Esther Avalos, Zaiwei Wang, Yuhang Liu, Anand Agarwalla, Brian Irving Carlsen, Fan Fu, Aditya Mishra, Haizhou Lu, Felix Thomas Eickemeyer, Xianfu Zhang, Likai Zheng, Ying Yang

Mixtures of cations or halides with FAPbI(3) (where FA is formamidinium) lead to high efficiency in perovskite solar cells (PSCs) but also to blue-shifted absorption and long-term stability issues caused by loss of volatile methylammonium (MA) and phase se ...

American Association for the Advancement of Science2020

High-valence metals improve oxygen evolution reaction performance by modulating 3dmetal oxidation cycle energetics

Ye Zhang, Yelin Hu, Zhen Cao, Yang Li, Jun Li, Bo Zhang, Ziyun Wang, Likai Zheng

Multimetal oxyhydroxides have recently been reported that outperform noble metal catalysts for oxygen evolution reaction (OER). In such 3d-metal-based catalysts, the oxidation cycle of 3dmetals has been posited to act as the OER thermodynamic-limiting proc ...

NATURE RESEARCH2020