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Exciton

About: Exciton is a research topic. Over the lifetime, 31603 publications have been published within this topic receiving 810642 citations.


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Journal ArticleDOI
TL;DR: In this paper, three triphenyl benzene derivatives of 1,3,5-tri(m-pyrid-2-yl-phenyl)benzene (Tm2PyPB), Tm3PyPB and Tm4PyPB, containing pyridine rings at the periphery, are developed as electron-transport and hole/exciton-blocking materials for iridium(III) bis(4,6-(di-fluorophenyl)pyrinato-N,C2′)picolinate (FIrpic)-
Abstract: Three triphenyl benzene derivatives of 1,3,5-tri(m-pyrid-2-yl-phenyl)benzene (Tm2PyPB), 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (Tm3PyPB) and 1,3,5-tri(m-pyrid-4-yl-phenyl)benzene (Tm4PyPB), containing pyridine rings at the periphery, are developed as electron-transport and hole/exciton-blocking materials for iridium(III) bis(4,6-(di-fluorophenyl)pyridinato-N,C2′)picolinate (FIrpic)-based blue phosphorescent organic light-emitting devices. Their highest occupied molecular orbital and lowest unoccupied molecular orbital (LUMO) energy levels decrease as the nitrogen atom of the pyridine ring moves from position 2 to 3 and 4; this is supported by both experimental results and density functional theory calculations, and gives improved electron-injection and hole-blocking properties. They exhibit a high electron mobility of 10−4–10−3 cm2 V−1 s−1 and a high triplet energy level of 2.75 eV. Confinement of FIrpic triplet excitons is strongly dependent on the nitrogen atom position of the pyridine ring. The second exponential decay component in the transient photoluminescence decays of Firpic-doped films also decreases when the position of the nitrogen atom in the pyridine ring changes. Reduced driving voltages are obtained when the nitrogen atom position changes because of improved electron injection as a result of the reduced LUMO level, but a better carrier balance is achieved for the Tm3PyPB-based device. An external quantum efficiency (EQE) over 93% of maximum EQE was achieved for the Tm4PyPB-based device at an illumination-relevant luminance of 1000 cd m−2, indicating reduced efficiency roll-off due to better confinement of FIrpic triplet excitons by Tm4PyPB in contrast to Tm2PyPB and Tm3PyPB.

200 citations

Journal ArticleDOI
TL;DR: Close examination of exciton PL intensity time traces of single CdSe(CdZnS) core(shell) nanocrystals reveals that the dark state PL quantum yield can be 10 times less than the biexciton PL quantum yields, which directly contradict the predictions of the charging model.
Abstract: Semiconductor nanocrystals emit light intermittently; i.e., they “blink,” under steady illumination. The dark periods have been widely assumed to be due to photoluminescence (PL) quenching by an Auger-like process involving a single additional charge present in the nanocrystal. Our results challenge this long-standing assumption. Close examination of exciton PL intensity time traces of single CdSe(CdZnS) core (shell) nanocrystals reveals that the dark state PL quantum yield can be 10 times less than the biexciton PL quantum yield. In addition, we observe spectrally resolved multiexciton emission and find that it also blinks with an on/off ratio greater than 10:1. These results directly contradict the predictions of the charging model.

200 citations

Journal ArticleDOI
TL;DR: This work reports on strong interaction between localized surface plasmons in silver nanoprisms and excitons and trions in monolayer tungsten disulfide (WS2) and shows that the plasmon-exciton interactions can be efficiently tuned by controlling the charged versus neutral exciton contribution to the coupling process.
Abstract: Formation of dressed light-matter states in optical structures, manifested as Rabi splitting of the eigen energies of a coupled system, is one of the key effects in quantum optics. In pursuing this regime with semiconductors, light is usually made to interact with excitons, electrically neutral quasiparticles of semiconductors; meanwhile interactions with charged three-particle states, trions, have received little attention. Here, we report on strong interaction between localized surface plasmons in silver nanoprisms and excitons and trions in monolayer tungsten disulfide (WS2). We show that the plasmon–exciton interactions in this system can be efficiently tuned by controlling the charged versus neutral exciton contribution to the coupling process. In particular, we show that a stable trion state emerges and couples efficiently to the plasmon resonance at low temperature by forming three bright intermixed plasmon–exciton–trion polariton states. Our findings open up a possibility to exploit electrically c...

200 citations

Journal ArticleDOI
TL;DR: Variational calculations of the ground-state exciton energy in quantum wells have been done, and the results agree with the experimental data, providing evidence for exciton confinement in organic quantum-well structures.
Abstract: Multiple-quantum-well structures based on two crystalline organic semiconductors, namely, 3,4,9,10 perylenetetracarboxylic dianhydride and 3,4,7,8 naphthalenetetracarboxylic dianhydride, have been grown by organic molecular-beam deposition. Both optical-absorption and time-resolved photoluminescence measurements reveal a significant effect on the binding energy and the radiative recombination probability of excitons due to localization of carriers. Variational calculations of the ground-state exciton energy in quantum wells have been done, and the results agree with the experimental data. This provides evidence for exciton confinement in organic quantum-well structures.

199 citations

Journal ArticleDOI
TL;DR: In this article, an unexpectedly enhanced polar exciton-LO-phonon interaction for such strained low-symmetry QDs is found, and calculations in the adiabatic approximation indicate that the particular quantum confinement and piezoelectric effect together account for the enhanced coupling.
Abstract: Phonon-assisted exciton transitions in self-organized InAs/GaAs quantum dots (QDs) are investigated by photoluminescence (PL) and PL excitation spectroscopy. An unexpectedly enhanced polar exciton-LO-phonon interaction for such strained low-symmetry QDs is found. Calculations in the adiabatic approximation indicate that the particular quantum confinement and piezoelectric effect together account for the enhanced coupling. The results provide new insights into the long-standing problem of the exciton-phonon interaction in zero-dimensional systems.

199 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,269
20222,623
20211,045
20201,157
20191,096
20181,057