Carrier Generation, Recombination, and Transport in Organic Crystals

Pope, Martin; Swenberg, Charles E.

doi:10.1007/978-94-009-6366-5_8

Cited by 545 publications

(870 citation statements)

References 35 publications

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“…The basic excitation mechanism of single dopant molecules by charge carriers is described by Langevin recombination 25 . In this model, a charge carrier gets locally trapped, attracting charge carriers of opposite polarity once they pass within a certain capture radius of the dopant molecule.…”

Section: Discussionmentioning

confidence: 99%

“…To electrically excite single phosphorescent molecules and to obtain detectable emission rates, bipolar current densities of at least 1 mA cm − 2 are required for charge carrier capture cross-sections in the order of 20 nm (ref. 25) in radius and triplet-state emissive lifetimes of 1 µs. Besides adequate charge-carrier densities, it is essential that the current density meets certain stability requirements.…”

Section: Optical Excitation Of Single Phosphorescent Moleculesmentioning

confidence: 99%

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Electrically driven photon antibunching from a single molecule at room temperature

et al. 2012

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single-photon emitters have been considered for applications in quantum information processing, quantum cryptography and metrology. For the sake of integration and to provide an electron photon interface, it is of great interest to stimulate single-photon emission by electrical excitation as demonstrated for quantum dots. Because of low exciton binding energies, it has so far not been possible to detect sub-Poissonian photon statistics of electrically driven quantum dots at room temperature. However, organic molecules possess exciton binding energies on the order of 1 eV, thereby facilitating the development of an electrically driven single-photon source at room temperature in a solid-state matrix. Here we demonstrate electroluminescence of single, electrically driven molecules at room temperature. By careful choice of the molecular emitter, as well as fabrication of a specially designed organic lightemitting diode structure, we were able to achieve stable single-molecule emission and detect sub-Poissonian photon statistics.

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Section: Discussionmentioning

confidence: 99%

Section: Optical Excitation Of Single Phosphorescent Moleculesmentioning

confidence: 99%

Electrically driven photon antibunching from a single molecule at room temperature

et al. 2012

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“…1(a)), the derivation of which is nicely shown in the book by Pope and Swenberg, 10 assumes that the rate limiting factor for recombination is the finding of the respective recombination partners (1), and not the actual recombination rate (2). Neglecting process (2) as it is faster than (1), the finding of electron and hole depends on the sum of their diffusivities or-considering the Einstein relation-their mobilities.…”

Section: Model a Existing Models For The Reduced Langevin Recombmentioning

confidence: 99%

“…7,8 A detailed analysis considering the interplay of these mechanisms has still to be done, as already the separate processes are not completely described yet. Concerning nongeminate recombination, classically the bimolecular Langevin formalism 9,10 has been used for low mobility materials. However, already in 1997, reports on a reduced rate as compared to Langevin's derivation were discussed for polaron recombination in conjugated polymers, 11 and recently a similar reduction was found for polymer-fullerene solar cells.…”

Section: Introductionmentioning

confidence: 99%

Origin of reduced polaron recombination in organic semiconductor devices

2009

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We propose a model to explain the reduced bimolecular recombination rate found in state-of-the-art bulk heterojunction solar cells. When compared to the Langevin recombination, the experimentally observed rate is one to four orders of magnitude lower, but gets closer to the Langevin case for low temperatures. Our model considers the organic solar cell as device with carrier concentration gradients, which form due to the electrode/blend/electrode device configuration. The resulting electron concentration under working conditions of a solar cell is higher at the cathode than at the anode, and vice versa for holes. Therefore, the spatially dependent bimolecular recombination rate, proportional to the local product of electron and hole concentration, is much lower as compared to the calculation of the recombination rate based on the extracted and thus averaged charge carrier concentrations. We consider also the temperature dependence of the recombination rate, which can for the first time be described with our model.

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“…[11] The invariant PLQY along with an increase of FWHM of the PL and the emission tail at longer wavelengths observed for G2 and G3 are consistent with the emission originating from excimer-like states, as we have previously observed and discussed in this and related systems. [11,15] To determine whether the differences in sensing performance previously observed in solutionbased measurements translate to the solid-state, we measured the changes in film PL as they were exposed to analyte vapor across a range of concentrations and exposure times using a more controlled method to that previously reported. [16] It is worth noting that while Stern-Volmer measurements provide a means of quantitatively comparing the quenching efficiency of different sensing material and analyte combinations, an equivalent methodology does not exist for the solid-state.…”

Section: Resultsmentioning

confidence: 99%

Assessing the sensing limits of fluorescent dendrimer thin films for the detection of explosive vapors

Shoaee

Chen

Cavaye

et al. 2017

Sensors and Actuators B: Chemical

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Photoluminescence quenching of organic thin films is a promising technique for the detection of vapors from explosives. The photoluminescence quenching response depends on the energetics of electron transfer from the photo-excited sensing material to the analytes, the vapor pressure of the analyte, and the diffusion process of the analytes in the sensing films. It is critical that the performance of a potential sensing material be evaluated in the solid-state with a range of analytes and across a range of vapor concentrations to ensure high sensitivities through noncontact sampling is achievable. We have investigated the photoluminescence quenching of three generations of carbazole-based dendrimers across a range of nitro-containing analyte vapor concentrations, including the TNT by-product 2,4-dinitrotoluene (DNT), and the tagging agent 2,3-dimethyl-2,3-dinitrobutane (DMNB). We show that the performance of all three dendrimer generations in the solid-state is near identical. Furthermore, we show that these dendrimers have a high affinity towards nitroaromatic compounds with parts per billion sensitivity, which makes them ideal for trace-level detection.

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Carrier Generation, Recombination, and Transport in Organic Crystals

Cited by 545 publications

References 35 publications

Electrically driven photon antibunching from a single molecule at room temperature

Electrically driven photon antibunching from a single molecule at room temperature

Origin of reduced polaron recombination in organic semiconductor devices

Assessing the sensing limits of fluorescent dendrimer thin films for the detection of explosive vapors

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