Bimolecular recombination in polymer electronic devices

Groves, Chris

doi:10.1103/physrevb.78.155205

Cited by 159 publications

(165 citation statements)

References 37 publications

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“…However, to our knowledge, this explanation has not been experimentally verified as of yet. Groves et al 25 perform Monte Carlo simulations of electrons and holes in a blend system with hopping transport, and study deviations from the Langevin theory of bimolecular recombination inin view of bulk devices and field effect transistors. For bulk heterojunctions, they point out that the effect of energetic disorder, domain sizes and electron-hole mobility mismatch leads to ζstatic of only between 0.1 and 1.…”

Section: Resultsmentioning

confidence: 99%

“…acceptor material of the polymer-fullerene blend can have different dielectric constants, 30 or (c) deviations from the Langevin recombination factor due to energetic disorder, size of the donor-acceptor domains, and mismatch between the electron and hole mobility. 25 Szmytkowski 30 calculates a temperature independent recombination reduction factor,…”

Section: Resultsmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Origin of reduced polaron recombination in organic semiconductor devices

2009

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“…Albrecht and Bässler 27 studied the recombination rate in the independent particle ͑Boltzmann͒ limit using three-dimensional ͑3D͒ Monte Carlo ͑MC͒ calculations, and found ͑i͒ at small fields no significant deviation from the Langevin rate when varying the disorder parameter and ͑ii͒ a significant enhancement of the recombination rate with respect to the Langevin rate with increasing field. In contrast, Groves and Greenham 28 recently found from a MC study that in homogeneous systems ͑a box with periodic boundary conditions͒ with isotropic mobilities the bimolecular recombination rate can be larger than given by the Langevin formula when ӷ k B T. So far, no systematic study of the charge-carrier density dependence of the recombination rate has been performed.…”

Section: Introductionmentioning

confidence: 99%

Effects of disorder on the current density and recombination profile in organic light-emitting diodes

Coehoorn

Mensfoort

2009

Phys. Rev. B

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“…9 Since our original work, DMC has been used as a general investigation of morphology, [10][11][12] or to examine specific loss mechanisms. 13,14 The influence of polymer-blend morphologies consisting of coiled polymer chains on charge transport and photocurrent generation in polymer blends has also been studied using Monte Carlo simulation methods. 15 Drift-diffusion modelling has also been successfully used to model organic solar cells.…”

Section: Introductionmentioning

confidence: 99%

Bicontinuous minimal surface nanostructures for polymer blend solar cells

Kimber

Walker

Schröder‐Turk

et al. 2010

Phys. Chem. Chem. Phys.

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This paper presents the first examination of the potential for bicontinuous structures such as the gyroid structure to produce high efficiency solar cells based on conjugated polymers. The solar cell characteristics are predicted by a simulation model that shows how the morphology influences device performance through integration of all the processes occurring in organic photocells in a specified morphology. In bicontinuous phases, the surface defining the interface between the electron and hole transporting phases divides the volume into two disjoint subvolumes. Exciton loss is reduced because the interface at which charge separation occurs permeates the device so excitons have only a short distance to reach the interface. As each of the component phases is connected, charges will be able to reach the electrodes more easily. In simulations of the current-voltage characteristics of organic cells with gyroid, disordered blend and vertical rod (rods normal to the electrodes) morphologies, we find that gyroids have a lower than anticipated performance advantage over disordered blends, and that vertical rods are superior. These results are explored thoroughly, with geminate recombination, i.e. recombination of charges originating from the same exciton, identified as the primary source of loss. Thus, if an appropriate materials choice could reduce geminate recombination, gyroids show great promise for future research and applications.

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Bimolecular recombination in polymer electronic devices

Cited by 159 publications

References 37 publications

Origin of reduced polaron recombination in organic semiconductor devices

Origin of reduced polaron recombination in organic semiconductor devices

Effects of disorder on the current density and recombination profile in organic light-emitting diodes

Bicontinuous minimal surface nanostructures for polymer blend solar cells

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