Résumé: The proposed project addresses the bottlenecks of quantum state initialization and coherence by developing optically addressable, photogenerated high spin states. By coupling organic chromophores with paramagnetic transition metal and lanthanide centers or with stable organic radicals, this project aim to study Enhanced Intersystem Crossing (EISC) to achieve non-thermal spin hyperpolarization upon pulsed optical excitation. The use of a modular assembly strategy, which combines covalent and supramolecular linkers, allows systematical design and investigation of spin properties-structure realtionships in such systems »
Speaker : Professeure Safae AAZOU (Université Mohammed V de Rabat Maroc)
Abstract: Tandem solar cells can exceed the efficiency limits of single-junction devices. In this study, we investigate the use of TiO₂ buffer layer as an alternative to CdS in kesterite/c-Si tandem solar cells through combined optical and electrical simulations. The results show that TiO₂ reduces parasitic absorption and interface recombination, leading to improved optoelectronic performance. An optimized CZTGeS/c-Si tandem structure achieved an efficiency close to 20%. These findings highlight the potential of TiO₂ buffer layers for developing efficient and environmentally friendly kesterite/silicon tandem solar cells.
Pour tout contact : Dris Ihiawakrim (0388107015 – dris.ihiawakrim@ipcms.unistra.fr)
Martin SAROTT (Zernike Institute for Advanced Materials ; Groningen Cognitive Systems and Materials Center (CogniGron) University of Groningen, The Netherlands )
Dr. Daniel J. Cutler (Marie SkłodowskaCurie Actions Global Postdoctoral Fellow
LabMolDesign / Rawson Group ; Universitat de Barcelona / University of Windsor )
Résumé : The field of molecular magnetism focuses on the development of magnetic materials by the utilization of the so-called “bottom-up” approach, using paramagnetic building blocks to prepare new materials with desirable magnetic properties.1,2 Some common choices of building blocks include transition metal (TM) and lanthanide (Ln) ions, and open-shell radicals. The combination of these starting materials into different architectures can tune the magnetic properties of the material to afford sought after magnetic properties ranging from slow magnetic relaxation dynamics, spin crossover behaviour, magnetic frustration and high-spin bearing species. This seminar will present work based on two themes, TM and Ln coordination cluster chemistry and main group thiazyl radical chemistry.
Polymetallic coordination clusters are some of the most well studied magnetic molecules with the dodecametallic Mn12-acetate cluster being the first reported Single Molecule Magnet (SMM).3 Here we present work building cluster compounds with TM ions (CuII and FeIII) and Ln ions (DyIII, TbIII and GdIII) using flexible pyridyl alkoxide ligands. The CuIILnIII butterfly system displays a “switching on” effect where the addition of auxiliary un-paired spins, in the form of CuII, switches on the slow magnetic relaxation of the molecule. Work with FeIII ions focuses on the effects on cluster preparation when using chiral vs racemic chelates. We report a family of six cluster compounds ranging from a simple Fe2 dimer to a Fe10 decamer.
Main group thiazyl radicals have proven to be promising candidates for designing tuneable magnetic materials. To date work with these radicals have afforded material with properties varying from canted anti-ferromagnetism,4 single molecule magnetism5 and spin crossover.6 The 4- pyDTA radical, presented, displays hysteric spin crossover behaviour in the solid state as a result of a first order phase transition. Investigations with variable temperature EPR, magnetometry and XRD methods elucidate the nature of this transition
References:
1.- M. B. Duriska, S. M. Neville, B. Moubaraki, J. D. Cashion, G. J. Halder, K. W. Chapman, C. Balde, J.-F. Létard, K. S. Murray, C. J. Kepert and S. R. Batten, Angewandte Chemie International Edition, 2009, 48, 2549–2552.
2.- S. Sanz, H. M. O’Connor, E. M. Pineda, K. S. Pedersen, G. S. Nichol, O. Mønsted, H. Weihe, S. Piligkos, E. J. L. McInnes, P. J. Lusby and E. K. Brechin, Angewandte Chemie International Edition, 2015, 54, 6761–6764.
3.- H. J. Eppley, H.-L. Tsai, N. de Vries, K. Folting, G. Christou and D. N. Hendrickson, Journal of the American Chemical Society, 1995, 117, 301–317.
4.- D. Leckie, M. Harb, N. Mroz, J. D. Wrixon, J. Campo, A. Arauzo, H. Bakhshi, M. Pilkington and J. M. Rawson, J. Am. Chem. Soc., 2024, 146, 31371–31376.
5.- E. M. Fatila, M. Rouzieìres, M. C. Jennings, A. J. Lough, R. Clérac and K. E. Preuss, Journal of the American Chemical Society, 2013, 135, 9596–9599.
6.- W. Fujita and and K. Awaga, Science, 1999, 286, 261–262.
