Recombination Dynamics as a Key Determinant of Open Circuit Voltage in Organic Bulk Heterojunction Solar Cells: A Comparison of Four Different Donor Polymers

Maurano, Andrea; Hamilton, Rick; Shuttle, Christopher G.; Ballantyne, Amy M.; Nelson, Jenny; O’Regan, Brian C.; Zhang, Weimin; McCulloch, Iain; Azimi, Hamed; Morana, Mauro; Brabec, Christoph J.; Durrant, James R.

doi:10.1002/adma.201002360

Cited by 378 publications

(421 citation statements)

References 20 publications

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“…Intensity-dependent open-circuit voltage measurements were performed to probe the recombination mechanisms in these OSCs 33,34 . Figure 5a shows the V OC versus ln(I) (where I is the light intensity) for devices with different AgNPs concentration.…”

Section: Resultsmentioning

confidence: 99%

Uncovering loss mechanisms in silver nanoparticle-blended plasmonic organic solar cells

et al. 2013

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There has been much controversy over the incorporation of organic-ligand-encapsulated plasmonic nanoparticles in the active layer of bulk heterojunction organic solar cells, where both enhancement and detraction in performance have been reported. Here through comprehensive transient optical spectroscopy and electrical characterization, we demonstrate evidence of traps responsible for performance degradation in plasmonic organic solar cells fabricated with oleylamine-capped silver nanoparticles blended in the poly (3-hexylthiophene):[6,6]-phenyl-C 61-butyric acid methyl ester active layer. Despite an initial increase in exciton generation promoted by the presence of silver nanoparticles, transient absorption spectroscopy reveals no increase in the later free polaron population-attributed to fast trapping of polarons by nearby nanoparticles. The increased trap-assisted recombination is also reconfirmed by light intensity-dependent electrical measurements. These new insights into the photophysics and charge dynamics of plasmonic organic solar cells would resolve the existing controversy and provide clear guidelines for device design and fabrication.

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Section: Resultsmentioning

confidence: 99%

Uncovering loss mechanisms in silver nanoparticle-blended plasmonic organic solar cells

et al. 2013

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“…In general, V oc is determined by a competition between recombination and generation of charges. 15 As a result, recombination mechanisms can be excellently extracted by studying the open-circuit voltage as a function of generation rate, which can be tuned linearly by variation of the incident light intensity. For the solar cells investigated here, the dominant recombination mechanism is bimolecular, as evidenced by the slope of kT/q in the V oc -intensity measurements in Fig.…”

Section: -2mentioning

confidence: 99%

Origin of the dark-current ideality factor in polymer:fullerene bulk heterojunction solar cells

Wetzelaer

Kuik

Lenes

et al. 2011

Applied Physics Letters

282

217

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“…14 Once charge carriers are free, there is a probability that positive and negative charge carriers will meet at an interface, resulting again in the formation of a CT state, which can redissociate or recombine. At open circuit, this type of recombination balances with the free carrier generation, 15 hence the open-circuit voltage V oc of donor-acceptor solar cells is found to be related to properties of the interfacial CT state. [16][17][18] V oc under solar illumination can be linearly correlated with the energy of the CT state (E CT ).…”

Section: Introductionmentioning

confidence: 99%

Polarization anisotropy of charge transfer absorption and emission of aligned polymer:fullerene blend films

2012

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An improved understanding of the electronic structure of interfacial charge transfer (CT) states is of importance due to their crucial role in charge carrier generation and recombination in organic donor-acceptor (DA) solar cells. DA combinations with a small difference between the energy of the CT state (E CT ) and energy of the donor exciton (E D * ) are of special interest since energy losses due to electron transfer are minimized, resulting in an optimized open-circuit voltage. In that case, the CT state can be considered as a resonance mixture, containing character of a fully ionic state (D + A − ) and of the local polymer excited state (D * A). We show that the D * A contribution to the overall CT state wave function can be determined by measurements of the polarization anisotropy of CT absorption and emission of polymer:fullerene blends with aligned polymer chains. We study two donor polymers, P3HT and TQ1, blended with fullerene acceptors with different ionization potentials, allowing variation of the E D * − E CT difference. We find that, upon decreasing E D * − E CT , the local excitonic D * A character of the CT state increases, resulting in a decreased fraction of charge transferred and an increased transition dipole moment. For typical polymer:fullerene systems, this effect is expected to become detrimental for device performance if E D * − E CT < 0.1 eV. This however, depends on the electronic coupling between D * A and D + A − , which we experimentally estimate to be ∼ 6 meV for the TQ1:PCBM system.

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Recombination Dynamics as a Key Determinant of Open Circuit Voltage in Organic Bulk Heterojunction Solar Cells: A Comparison of Four Different Donor Polymers

Cited by 378 publications

References 20 publications

Uncovering loss mechanisms in silver nanoparticle-blended plasmonic organic solar cells

Uncovering loss mechanisms in silver nanoparticle-blended plasmonic organic solar cells

Origin of the dark-current ideality factor in polymer:fullerene bulk heterojunction solar cells

Polarization anisotropy of charge transfer absorption and emission of aligned polymer:fullerene blend films

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