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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.


Papers
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Journal ArticleDOI
TL;DR: In this article, the short-circuit current density of organic solar cells based on poly (3hexylthiophene)(P3HT)/6,6-phenyl C61-butyric acid methyl ester (PCBM) blend is investigated.

288 citations

Journal ArticleDOI
20 Jan 2016-ACS Nano
TL;DR: It is shown that at low temperature single colloidal cesium lead halide nanocrystals exhibit stable, narrow-band emission with suppressed blinking and small spectral diffusion, representing a significant acceleration compared to other common quantum emitters.
Abstract: Metal-halide semiconductors with perovskite crystal structure are attractive due to their facile solution processability, and have recently been harnessed very successfully for high-efficiency photovoltaics and bright light sources. Here, we show that at low temperature single colloidal cesium lead halide (CsPbX3, where X = Cl/Br) nanocrystals exhibit stable, narrow-band emission with suppressed blinking and small spectral diffusion. Photon antibunching demonstrates unambiguously nonclassical single-photon emission with radiative decay on the order of 250 ps, representing a significant acceleration compared to other common quantum emitters. High-resolution spectroscopy provides insight into the complex nature of the emission process such as the fine structure and charged exciton dynamics.

287 citations

Journal ArticleDOI
TL;DR: In this article, femtosecond transient absorption measurements on the semiconductor conjugated polymers poly(9,9-dioctylfluorene) (F8) and poly( 9,9 -dialflorenne-co-benzothiadiazole)(F8BT) are presented.
Abstract: We present femtosecond transient absorption measurements on the semiconductor conjugated polymers poly(9,9-dioctylfluorene) (F8) and poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT). Detailed photophysical modeling reveals that, in F8, sequential excitation, first to the lowest singlet excited state, and then to a higher-energy state resonant with the pump photon energy, is predominantly responsible for the rapid $(l150\mathrm{fs})$ dissociation of photoinduced excitons. Resonant sequential excitation accesses high-energy states that can promptly evolve to charged or triplet states. In F8BT, however, we find that sequential excitation plays a lesser role in fast polaron-pair generation, and that exciton bimolecular annihilation can explain the charge population. We suggest that the electrophilic benzothiadiazole groups in F8BT facilitate charge formation by dissociation of the excited state formed by exciton-exciton annihilation. Modeling also reveals that exciton bimolecular annihilation can occur via two separate and competing processes. We find that in F8, the dominant mechanism involves exciton diffusion and collision. In F8BT, however, additional annihilation of spatially separated excitons occurs when they interact through the F\"orster transfer mechanism, where the critical distance for annihilation in F8BT is 4 nm.

287 citations

Journal ArticleDOI
TL;DR: In this paper, the Coulomb interaction between the charges within precursor geminate pairs was investigated and a model that explains how excitons can efficiently dissociate into free carriers at an intrinsic polymer/acceptor interface was proposed.
Abstract: Although doping of a conjugated polymer by electron acceptors strongly facilitates exciton dissociation into geminate pairs of carriers, the yield of free carrier photogeneration can be high only at high doping levels, that is, in polymer/acceptor blends. We suggest a model that explains how excitons can efficiently dissociate into free carriers at an intrinsic polymer/acceptor interface despite the Coulomb interaction between the charges within precursor geminate pairs.

286 citations

Journal ArticleDOI
TL;DR: It is theoretically shown that efficient generation of multi-electron-hole pairs by a single photon observed recently in semiconductor nanocrystals1-4 is caused by breaking the single electron approximation for carriers with kinetic energy above the effective energy gap.
Abstract: We have theoretically shown that efficient generation of multi-electron−hole pairs by a single photon observed recently in semiconductor nanocrystals1-4 is caused by breaking the single electron approximation for carriers with kinetic energy above the effective energy gap. Due to strong Coulomb interaction, these states form a coherent superposition with charged excitons of the same energy. This concept allows us to define the conditions for dominant two-exciton generations by a single photon: the thermalization rate of a single exciton, initiated by light, should be lower than both the two-exciton state thermalization rate and the rate of Coulomb coupling between single and two exciton states. Possible experimental manifestations of our model are discussed.

286 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