Publications associées à Nano-emitting Heterostructures Violate Optical Reciprocity and Enable Efficient Photoluminescence in Halide-Segregated Methylammonium-Free Wide Bandgap Perovskites

III-N blue-emitting epi-structures with high densities of dislocations: Fundamental mechanisms for efficiency improvement and applications

Since the dawn of humanity, human beings seeked to light their surroundings for their well-being, security and development. The efficiency of ancient lighting devices, e.g. oil lamps or candles, was in the order of 0.03-0.04% and jumped to 0.4-0.6% with th ...

EPFL2024

Study of growth-induced point defects and their impact on InGaN-based optoelectronic devices

Yao Chen

GaN exhibits a decomposition tendency for temperatures far below its melting point and common growth temperatures used in metal-organic vapour phase epitaxy (MOVPE).This characteristic is known to be a major obstacle for realising GaN bulk substrate. There ...

EPFL2024

Investigating Non-equilibrium Physics in Wide Bandgap Semiconductors and Quantum Materials via Ultrafast Spectroscopy

Hui-Yuan Chen

This thesis uses femtosecond laser spectroscopy in studying strong correlation in condensed matters that are pertinent to future technology: a wide bandgap perovskite and a quantum material, with the employment of ultrafast time-resolved spectroscopy in th ...

EPFL2024

Shortwave Infrared-Sensitive, Narrowband Organic Upconversion Devices with a Gain

Wei-Hsu Hu

Sensing and imaging of light in the shortwave infrared (SWIR) range is increasingly used in various fields, including bio-imaging, remote sensing, and semiconductor process control. SWIR-sensitive organic photodetectors (OPDs) are promising because organic ...

EPFL2024

Identification and Mitigation of Degradation Mechanisms Induced by Heat and Light in NiOx-based Perovskite Solar Cells

Marion Solange Madeleine Dussouillez

Perovskite solar cells (PSCs) offer an attractive solution to increase the efficiency of PV panels via perovskite/silicon tandems thanks to their potential cost-effectiveness and high efficiency. In inverted PSC architecture (p-i-n), commonly used hole con ...

EPFL2024

Enhancing Efficiency of Industrially-Compatible Monolithic Perovskite/Silicon Tandem Solar Cells with Dually-Mixed Self-Assembled Monolayers

Mohammad Khaja Nazeeruddin, Peng Gao, Ye Yang, Chaohui Li

The antisolvent-assisted spin-coating still lags behind the thermal evaporation method in fabricating perovskite films atop industrially textured silicon wafers in making monolithic perovskite/silicon solar cells (P/S-TSCs). The inhomogeneity of hole-selec ...

Wiley-V C H Verlag Gmbh2024

Investigation of room-temperature single-photon emitters in GaN-based materials and GaN/AlN quantum dots

Johann Nicolaï Stachurski

Over the past decade, quantum photonics platforms aiming at harnessing the fundamental properties of single particles, such as quantum superposition and quantum entanglement, have flourished. In this context, single-photon emitters capable of operating at ...

EPFL2024

Exciton migration in two-dimensional materials

Excitons play an essential role in the optical response of two-dimensional materials. These are bound states showing up in the band gaps of many-body systems and are conceived as quasiparticles formed by an electron and a hole. By performing real-time simu ...

Nature Portfolio2024

Computational Studies on the Stability of Organic-Inorganic Hybrid Halide Lead Perovskites

Mathias Dankl

Perovskite-based solar cells are currently the most rapidly advancing photovoltaic technology but concerns about their long-term stability are still impeding full-scale commercialization. This thesis provides computational insights into some of the stabili ...

EPFL2024

Hybrid organic/metal-oxide shells on semiconductor nanocrystals via colloidal atomic layer deposition

Ona Segura Lecina

The escalating energy demand and the imperative necessity to reduce the carbon footprint require transformative approaches to energy conversion. Materials chemistry plays a pivotal role in addressing these global challenges by developing novel materials fo ...

EPFL2024

Durable Perovskite Solar Cells with 24.5% Average Efficiency: The Role of Rigid Conjugated Core in Molecular Semiconductors

Michael Graetzel, Shaik Mohammed Zakeeruddin, Peng Wang, Felix Thomas Eickemeyer, Ming Ren

Efficient and robust n-i-p perovskite solar cells necessitate superior organic hole-transport materials with both mechanical and electronic prowess. Deciphering the structure-property relationship of these materials is crucial for practical perovskite sola ...

Wiley-V C H Verlag Gmbh2024

Elimination of buried interfacial voids for efficient perovskite solar cells

Bo Chen, Bin Ding, Yan Liu, Xianfu Zhang

Establishing optimal interfacial contact is crucial for enhancing the efficiency of perovskite solar cells (PSCs). However, formation of voids at buried interface of perovskite films often hinders this critical objective. Our investigation reveals that the ...

Elsevier2024

Photo-doping of spiro-OMeTAD for highly stable and efficient perovskite solar cells

Michael Graetzel, Jacques-Edouard Moser, Etienne Christophe Socie, Aaron Tomas Terpstra, George Cameron Fish, Kai Zhu

A widely used component of high-efficiency perovskite solar cells (PSCs) is the molecular hole-transport material (HTM) spiro-OMeTAD. This organic solid needs to be p-doped to acquire sufficient hole conductivity. However, the conventional doping method us ...

2024

Alleviating nanostructural phase impurities enhances the optoelectronic properties, device performance and stability of cesium-formamidinium metal-halide perovskites

Christophe Ballif, Aïcha Hessler-Wyser, Quentin Thomas Jeangros, Beat Ruhstaller, Mostafa Rabie Shlaly Bahr Othman, Daniel Anthony Jacobs, Christian Michael Wolff, Anaël Morgane Jaffrès, Austin George Kuba

The technique of alloying FA+ with Cs+ is often used to promote structural stabilization of the desirable alpha-FAPbI3 phase in halide perovskite devices. However, the precise mechanisms by which these alloying approaches improve the optoelectronic quality ...

Royal Soc Chemistry2024

High-Quality Data Enabling Universality of Band Gap Descriptor and Discovery of Photovoltaic Perovskites

Alfredo Pasquarello, Wei Chen, Haiyuan Wang

Extensive machine-learning-assisted research has been dedicated to predicting band gaps for perovskites, driven by their immense potential in photovoltaics. Yet, the effectiveness is often hampered by the lack of high-quality band gap data sets, particular ...

Amer Chemical Soc2024

Microstructural and electrical characterization of high temperature passivating contacts for silicon solar cells

Sofia Libraro

Recombination at metal/semiconductor interfaces represents the main limitation in mainstream c-Si solar cells, primarily based on the passivated emitter and rear cell (PERC) concept. Full-area passivating contacts based on SiOx/poly-Si stacks are a candida ...

EPFL2024

Structural divergence of molecular hole selective materials for viable p-i-n perovskite photovoltaics: a comprehensive review

Mohammad Khaja Nazeeruddin, Peng Gao, Paramaguru Ganesan

Perovskite solar cells (PSCs) have garnered significant attention within the photovoltaic research community due to their remarkable progress in just one decade. Among the device configurations, the p-i-n structured PSC offers several advantages, including ...

Royal Society of Chemistry2024

A thermotropic liquid crystal enables efficient and stable perovskite solar modules

Mohammad Khaja Nazeeruddin, Bin Ding, Jian Xu, Yong Ding, Cheng Liu

Perovskite solar cells have seen impressive progress in performance and stability, yet maintaining efficiency while scaling area remains a challenge. Here we find that additives commonly used to passivate large-area perovskite films often co-precipitate du ...

Nature Portfolio2024

Long live(d) CsPbBr3 superlattices: colloidal atomic layer deposition for structural stability

Raffaella Buonsanti, Alexander Nicolas Chen, Philippe Benjamin Green, Victoria Lapointe

Superlattice formation afforded by metal halide perovskite nanocrystals has been a phenomenon of interest due to the high structural order induced in these self-assemblies, an order that is influenced by the surface chemistry and particle morphology of the ...

Royal Soc Chemistry2024

Strain relaxation and multidentate anchoring in n-type perovskite transistors and logic circuits

Mohammad Khaja Nazeeruddin, Olga Syzgantseva

The engineering of tin halide perovskites has led to the development of p-type transistors with field-effect mobilities of over 70 cm2 V-1 s-1. However, due to their background hole doping, these perovskites are not suitable for n-type transistors. Ambipol ...

Nature Portfolio2024