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2D metal halide perovskites: a new fascinating playground for exciton fine structure investigations

Baranowski Michał, Dyksik Mateusz, Płochocka Paulina

Scientiae Radices

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2022

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Vol. 1, Iss. 1

3--25

EN

Two-dimensional (2D) metal halide perovskites are natural quantum wells which consist of low bandgap metal-halide slabs, surrounded by organic spacers barriers. The quantum and dielectric confinements provided by the organic part lead to the extreme exciton binding energy which results in a huge enhancement of exciton fine structure in this material system. This makes 2D perovskites a fascinating playground for fundamental excitonic physics studies. In this review, we summarize the current understanding and quantification of the exciton fine structure in 2D perovskites. We discuss what is the role of exciton fine structure in the optical response of 2D perovskites and how it challenges our understanding of this fundamental excitation. Finally, we highlight some controversy related to particularly large bright-dark exciton states splitting and high efficiency of light emission from these materials. This can result from the unique synergy of excitonic and mechanical properties of 2D perovskites crystals.

2

Określenie właściwości smarnych oleju napędowego z hydrokrakingu w funkcji zawartości estrów CHO

Kajdas Cz., Korycki J., Frydrych J.

Tribologia

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2007

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nr 2

219-227

PL

W pracy przedstawiono wybrane wyniki badań właściwości smarnych dodatków estrowych CHO (węgiel, wodór i tlen) w oleju napędowym z hydrokrakingu o zawartości siarki poniżej 5 ppm.

EN

The paper presents findings concerning lubricity proprieties of four CHO (carbon, hydrogen and oxygen) ester additives: cholesteryl acetate, methyl butyrate, methyl decanoate and cholesteryl palmitate, added to a hydrocracked diesel fuel base oil (LON) - containing less than 5 ppm sulphur - in the concentration range from 100 to 10000 ppm. One proposed a new mechanism of the ester hydrolysis and the formation of the film which is the result of the action of excited states produced during the friction process. The friction process releases the free energy to structures and molecules of the core, the surface layer, Langmuir - Blodget layer and the lubricant, and in the form of chemical energy at fragmentation of the additive molecules, and additionally also by generating electrons plus quanta of the energy such as : photons, phonons, excitons, solitons etc. [L. 2]. The formation of anion-radicals and tribochemical processes stimulated are processes releasing of the energy, small particles and fragments of molecules.

3

Śladem energii od deformacji do stanu wzbudzenia chemicznego

Korycki J.

Tribologia

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2005

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nr 2

153-172

PL

W pracy naszkicowano pogląd na przebieg procesów przekazywania energii w procesach tarcia i zużycia. Jako źródło energii wskazano procesy tarcia, powodujące procesy deformacji: rdzenia metalu, warstwy wierzchniej, warstwy Langmiura--Blodgeta i cieczy smarującej. Procesy te uwalniają energię swobodną do struktur i molekuł rdzenia, warstwy wierzchniej, warstwy Langmiura-Blodgeta i cieczy smarującej oraz w postaci energii chemicznej przy fragmentacji struktur czy molekuł, a też generując cząstki jako elektrony, kwanty energii jak: fotony, fonony, ekscytrony, soliony...

EN

The opinion on the course of processes of the transfer of the energy in friction and wear processes had been presented in this paper. As the source of energy was pointed friction process, causing deformation process: of the metal core, surface layer, Langmuir - Blodget layers and the bulk lubricant. These processes release the free energy to structures and molecules of the core, the surface layer, Langmuir - Blodget layer and the lubricant, and in the form of chemical energy at fragmentation of structures or molecules, and additionally also by generating electrons plus quanta of the energy such as: photons, phonons, excitons, solitons....

4

Microwave-enhanced exciton delocalisation in low-dimensional CdTe/CdMnTe and CdMnTe/CdMgTe quantum well structures

Godlewski M., Ivanov V. Yu., Khachapuridze A.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 4

346-354

EN

In this work we descrjbe new application of the technique of optically detected cyclotron resonance (ODCR) to the studies of localisation processes in quantum well structures of CdTe/CdMnTe and CdMnTe/CdMgrre. Interaction between rnicrowave-eated free carriers, at cyclotron. resonance conditions, and either site- or impurity-localised excitons results in modificatjon of photoluminescence from the sample. In consequence, cyclotron resonance of free carriers can be detected optically. We show here that the tech-nique of ODCR allows us to monitor processes of carrier/exciton localisation and also to evaluate their influence on radiative recombination processes in quantum well structures. We conclude that localisation effects are crucial to explain operation of CdTe/CdMnTe and CdMnTe/CdMgTe structures as light modulators.