Organic Light‐Emitting Diodes with Field‐Effect‐Assisted Electron Transport Based on <i>α‐bi;</i>,<i>ω‐bi;</i>‐Diperfluorohexyl‐quaterthiophene

Schols, Sarah; McClatchey, Christina; Rolin, Cédric; Bode, Dieter; Genoe, Jan; Heremans, Paul; Facchetti, Antonio

doi:10.1002/adfm.200800641

Cited by 14 publications

(8 citation statements)

References 46 publications

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“…90 In fact, oligothiophenes were extensively studied for their emissive properties (in solution or aggregates) [91][92][93][94] and used as organic light emitting diodes (OLEDs). 95 By increasing the p-electron conjugation and the chain length, the quantum yield and the lifetime of the emitting state increase, which implies less efficient internal conversion from S 1 to S 0 . For this reason, it is interesting to investigate the excited-state dynamics upon low-and high-energy photoexcitation, and to explore the decay mechanisms through the manifold of excited states.…”

Section: Exciton Dynamics After High-energy Excitations In Oligothiop...mentioning

confidence: 99%

Modeling ultrafast exciton deactivation in oligothiophenes via nonadiabatic dynamics

Fazzi

Barbatti

Thiel

2015

Phys. Chem. Chem. Phys.

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Ultrafast excited-state processes play a key role in organic electronics and photovoltaics, governing the way of how excitons can relax and separate. Through the use of nonadiabatic excited-state dynamics, relaxation processes were investigated at the sub-picosecond timescale in thiophene and oligothiophenes (nT, n = 2, 3, 4), prototype oligomers for efficient π-electron conjugated polymers adopted in photovoltaics. For thiophene, TDDFT and TDA nonadiabatic excited-state dynamics revealed ultrafast nonradiative relaxation processes through ring opening and ring puckering, bringing the system to an S1/S0 conical intersection seam. The computed relaxation time is 110 fs, matching well the experimental one (∼105 fs). In oligothiophenes (n = 2-4), high-energy (hot) excitations were considered. Exciton relaxation through the manifold of excited states to the lowest excited state is predicted to occur within ∼150-200 fs, involving bond stretching, ring puckering, and torsional oscillations. For the longer oligomer (4T), the ultrafast relaxation process leads to exciton localization over three thiophene rings in 150 fs. These data agree with the self-localization mechanism (∼100-200 fs) observed for poly(3-hexylthiophene) (P3HT) and shed light on the complex exciton relaxation dynamics occurring in π-conjugated oligomers of potential interest for optoelectronic applications.

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Section: Exciton Dynamics After High-energy Excitations In Oligothiop...mentioning

confidence: 99%

Modeling ultrafast exciton deactivation in oligothiophenes via nonadiabatic dynamics

Fazzi

Barbatti

Thiel

2015

Phys. Chem. Chem. Phys.

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“…These transport layers must be patterned to remove parasitic leakage paths between injecting electrodes. [34] As shown in the equivalent circuit of Figure 2c, the OG-OLET can be modeled as a n-TFT (i.e., n-type thin film transistor), a diode and a p-TFT connected in series. In the case of DFH-4T, this barrier is nevertheless sufficient to enable electron accumulation at the interface.…”

Section: Wwwadvelectronicmatdementioning

confidence: 99%

“…Finally, the DNTT, located at the bottom of the stack, is polycrystalline with a smooth morphology that does not compromise the growth of upper layers. On the other hand, DFH‐4T at the top is very rough which may help light outcoupling in the top emitting device (see Figure S3, Supporting Information) …”

Section: The Literature Benchmark Table Compares Select Olet Work Bamentioning

confidence: 99%

Overlapping‐Gate Organic Light‐Emitting Transistors

Lee

Genoe

et al. 2018

Adv Elect Materials

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The most common OLET architecture relies on a single gate (SG-OLETs) to control the transport of both electrons and holes toward the radiative recombination zone. As a consequence, hole-electron current balance in SG-OLETs can only be achieved at an intermediate gate bias. When driven at high currents, the current imbalance in SG-OLETs usually results in inefficient light emission very close to, or even under the source electrode of the transport layer with the lowest conductivity. [1,[11][12][13][14][15][16] In addition, the emission zone can unpredictably switch from one contact to the other upon small bias changes. [17][18][19][20][21][22] For these reasons, considerable roll-off is observed at increasing bias. Only a few fluorescent SG-OLETs have achieved external quantum efficiency (EQE) over 5% [12,13] and the peak EQE is only obtained at very low current and luminance. [12][13][14]17,[20][21][22] A variation around the SG-OLET topology is the vertical OLET where hole and electron sources are stacked above the gate whose main objective is to modulate charge injection from one of the sources into the device. [23][24][25][26] This compact topology intimately integrates the actions of switching and light emission, which is particularly suited for display applications. But the vertical OLET also suffers from roll-off when driven at high current densities. For all SG-OLET topologies, maintaining the high efficiency at high current level with balanced hole-electron currents remains a major challenge.Dual gate OLETs with two adjacent gates formed by the direct patterning of a single metallic film ("split-gate") have been proposed to decouple electron and hole currents and simultaneously achieve balanced transport at high current density. Unfortunately, the large spatial gap between the gates, more than 1 µm, forms a highly resistive active region which limits the current, resulting in low luminance (below 1000 cd m −2 ) and low EQE (1.3%). [27][28][29][30] Also "opposinggate" dual-gate OLETs have been proposed, where the active organic layer stack is vertically sandwiched between two insulators and two gates that each accumulate one species of charge carriers at either side of the active layer. But the vertical electric field between the gates strongly opposes charge injection and recombination into the central emissive layer, resulting in poor light emission. [31] In this work, we propose a novel dual-gate architecture, the overlapping-gates OLET (OG-OLET), that overcomes the shortcomings of previous OLET topologies. We show how this new device combines the important features of balanced electronhole transport up to high current density and light emission far A light-emitting transistor in which two gates, separated by an insulator, partially overlap in the center of the device is proposed. By accumulating charge carriers in dedicated transport layers, each gate independently controls charge injection into the emissive layer sandwiched between the transport layers. This structure combines the advantages of pinned...

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“…5,6 Including transport and emissive layers in the stacking configuration is a viable path to achieve both high current density and strong light intensity. 7,8 Such a multilayer approach can be easily implemented in vacuum deposited devices; nonetheless, it poses a serious challenge to solution processed devices as orthogonal solvents have to be considered for not destroying the already deposited underlayer. The first solution processed LET, the active layer of which is composed of a p-channel transport layer and an emissive polymer, was reported by Namdas et al 9 Low solubility of the transport layer in the solvent used for the emissive layer enabled fabrication of such a bilayer, thus resulting in a rather high external quantum efficiency (EQE) of 0.15% in spite of relatively low hole mobility ($10 À2 cm 2 V À1 s À1 ).…”

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confidence: 99%

Low optical turn-on voltage in solution processed hybrid light emitting transistor

Ablat

Kyndiah

Bachelet

et al. 2019

Applied Physics Letters

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Organic Light‐Emitting Diodes with Field‐Effect‐Assisted Electron Transport Based on α‐bi;,ω‐bi;‐Diperfluorohexyl‐quaterthiophene

Cited by 14 publications

References 46 publications

Modeling ultrafast exciton deactivation in oligothiophenes via nonadiabatic dynamics

Modeling ultrafast exciton deactivation in oligothiophenes via nonadiabatic dynamics

Overlapping‐Gate Organic Light‐Emitting Transistors

Low optical turn-on voltage in solution processed hybrid light emitting transistor

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