Publications de Amita Ummadisingu

Speciation of Lanthanide Metal Ion Dopants in Microcrystalline All-Inorganic Halide Perovskite CsPbCl3

David Lyndon Emsley, Dominik Józef Kubicki, Albert Hofstetter, Daniel Prochowicz, Amita Ummadisingu

Lanthanides are versatile modulators of optoelectronic properties owing to their narrow optical emission spectra across the visible and near-infrared range. Their use in metal halide perovskites (MHPs) has recently gained prominence, although their fate in ...

Amer Chemical Soc2024

Crystal-Size-Induced Band Gap Tuning in Perovskite Films

Michael Graetzel, Wolfgang Richard Tress, Amita Ummadisingu, Simone Meloni

A comprehensive picture explaining the effect of the crystal size in metal halide perovskite films on their opto-electronic characteristics is currently lacking. We report that perovskite nanocrystallites exhibit a wider band gap due to concurrent quantum ...

Wiley-VCH Verlag GmbH2021

Multi-Length Scale Structure of 2D/3D Dion-Jacobson Hybrid Perovskites Based on an Aromatic Diammonium Spacer

Michael Graetzel, David Lyndon Emsley, Jovana Milic, Thomas La Grange, Dominik Józef Kubicki, Amita Ummadisingu, Aditya Mishra, Algirdas Ducinskas

Dion-Jacobson (DJ) iodoplumbates based on 1,4-phenylenedimethanammonium (PDMA) have recently emerged as promising light absorbers for perovskite solar cells. While PDMA is one of the simplest aromatic spacers potentially capable of forming a DJ structure b ...

2021

Guanine‐Stabilized Formamidinium Lead Iodide Perovskites

Shaik Mohammed Zakeeruddin, Marko Mladenovic, David Lyndon Emsley, Yuhang Liu, Ursula Röthlisberger, Dan Ren, Linfeng Pan, Jovana Milic, Paramvir Ahlawat, Ulf Anders Hagfeldt

Formamidinium (FA) lead iodide perovskite materials feature promising photovoltaic performances and superior thermal stabilities. However, conversion of the perovskite α‐FAPbI3 phase to the thermodynamically stable yet photovoltaically inactive δ‐FAPbI3 ph ...

2020

Supramolecular Modulation of Hybrid Perovskite Solar Cells via Bifunctional Halogen Bonding Revealed by Two-Dimensional 19F Solid-State NMR Spectroscopy

Shaik Mohammed Zakeeruddin, Albert Hofstetter, David Lyndon Emsley, Marco Alejandro Ruiz Preciado, Jovana Milic, Dominik Józef Kubicki, Amita Ummadisingu

There has been an ongoing effort to overcome the limitations associated with the stability of hybrid organic–inorganic perovskite solar cells by using different organic agents as additives to the perovskite formulations. The functionality of organic additi ...

2020

Unravelling the structural complexity and photophysical properties of adamantyl-based layered hybrid perovskites

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ursula Röthlisberger, Wolfgang Richard Tress, Jovana Milic, Marko Mladenovic, Ulf Anders Hagfeldt, Mohammad Ibrahim Dar, Amita Ummadisingu, Paramvir Ahlawat

Layered hybrid perovskites comprising adamantyl spacer (A) cations based on the A(2)FA(n-1)Pb(n)I(3n+1)(n= 1-3, FA = formamidinium) compositions have recently been shown to act as promising materials for photovoltaic applications. While the corresponding p ...

Royal Society of Chemistry2020

Formamidinium-Based Dion-Jacobson Layered Hybrid Perovskites: Structural Complexity and Optoelectronic Properties

Michael Graetzel, Shaik Mohammed Zakeeruddin, Ursula Röthlisberger, Wolfgang Richard Tress, Jovana Milic, Marko Mladenovic, Ulf Anders Hagfeldt, Mohammad Ibrahim Dar, Amita Ummadisingu, Yang Li

Layered hybrid perovskites have emerged as a promising alternative to stabilizing hybrid organic-inorganic perovskite materials, which are predominantly based on Ruddlesden-Popper structures. Formamidinium (FA)-based Dion-Jacobson perovskite analogs are de ...

2020

A chain is as strong as its weakest link - Stability study of MAPbI(3) under light and temperature

Michael Graetzel, Ulf Anders Hagfeldt, Michael Saliba, Amita Ummadisingu, Pankaj Kumar Yadav, Silver Hamill Turren Cruz, Philippe Jürgen Holzhey

The stability of perovskite solar cells is a key issue for industrial development. One reason for this is the volatile organic methylammonium (MA) cation, which is prone to degas under elevated temperatures from the perovskite. At the same time, small amou ...

2019

Bifunctional Organic Spacers for Formamidinium-Based Hybrid Dion-Jacobson Two-Dimensional Perovskite Solar Cells

Michael Graetzel, Shaik Mohammed Zakeeruddin, Jovana Milic, Ulf Anders Hagfeldt, Mohammad Ibrahim Dar, Peng Wang, Yuhang Liu, Jiyoun Seo, Amita Ummadisingu, Yang Li

Three-dimensional (3D) perovskite materials display remarkable potential in photovoltaics owing to their superior solar-to-electric power conversion efficiency, with current efforts focused on improving stability. Two-dimensional (2D) perovskite analogues ...

AMER CHEMICAL SOC2019

Supramolecular Engineering for Formamidinium-Based Layered 2D Perovskite Solar Cells: Structural Complexity and Dynamics Revealed by Solid-State NMR Spectroscopy

Michael Graetzel, Shaik Mohammed Zakeeruddin, David Lyndon Emsley, Jovana Milic, Mohammad Ibrahim Dar, Dominik Józef Kubicki, Jiyoun Seo, Yang Li, Amita Ummadisingu, Jeong-Hyeok Im

Perovskite solar cells are one of the most promising photovoltaic technologies, although their molecular level design and stability toward environmental factors remain a challenge. Layered 2D Ruddlesden-Popper perovskite phases feature an organic spacer bi ...

WILEY-V C H VERLAG GMBH2019