Air exposure induced recombination in PTB7:PC<sub>71</sub>BM solar cells

Thomson, Stuart A. J.; Hogg, Stephen; Samuel, Ifor D. W.; Keeble, D. J.

doi:10.1039/c7ta03741d

Cited by 9 publications

(4 citation statements)

References 55 publications

(77 reference statements)

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“…In other words, the operational stability of the processed device is retained at 83.6%, which is comparatively higher than that shown by the as-cast device (78.2%). Although residual solvent additive could be a source of instability in organic solar cells, , the reason for the improved stability of the processed device is unclear.…”

Section: Resultsmentioning

confidence: 99%

Calamitic-Type Dipolar and Quadrupolar Chromophores with a Twisted Peripheral Handle: Structure–Property Outlook as Nonfullerene Acceptors for Binary Solar Cells

Raheem

Kumar

Murugan

et al. 2021

ACS Appl. Energy Mater.

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Symmetrical (14, 15) and unsymmetrical (16, 17) molecules possessing tetracyanobutadiene (TCBD) as a twisted end group on the carbazole/fluorene backbone were synthesized as nonfullerene acceptors (NFAs). Systematic structural correlation of these chromophores on the optoelectronic, electrochemical, and physicochemical properties revealed better acceptor properties for symmetrical (14, 15) compared to unsymmetrical analogues (16, 17). High molar absorptivity, deep HOMO–LUMOs, better electron-accepting capacity, along with other complementary molecular properties are some of the associated factors for the better acceptor character. In a binary solar cell configuration blended with P3HT donor, quadrupolar-type symmetrical chromophores (14, 15) displayed higher power conversion efficiencies over dipolar-type unsymmetrical chromophores (16, 17). In particular, 14 with an efficiency of 5.37% emerged as the best candidate with further enhancement to 6.30% upon additive processing. The dependence of processing on the improved photoinduced current was attributed to the better nanoscale morphology, crystallinity, and electron mobility. In terms of efficiency, it is the third highest for any TCBD-based NFA solar cells. Overall, this work validates the impact of a nonplanar TCBD auxiliary positioned within a calamitic-type π-framework to realize alternative NFAs. Viewed from a fundamental perspective, the initial results are promising, and further fine tuning of the molecular structure could possibly form an ideal acceptor for organic photovoltaics.

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Section: Resultsmentioning

confidence: 99%

Calamitic-Type Dipolar and Quadrupolar Chromophores with a Twisted Peripheral Handle: Structure–Property Outlook as Nonfullerene Acceptors for Binary Solar Cells

Raheem

Kumar

Murugan

et al. 2021

ACS Appl. Energy Mater.

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“…According to the e–h pair mechanism, EDMR occurs through the ESR transitions at the hole and electron that form an e–h pair. − Thus, when a difference exists in the resonance center of the spectrum between the electron and hole, the entire spectrum can exhibit an anisotropic line shape. The fitting results for the EDMR spectrum of the h-rich diode using the two-component Gaussians are shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Electron–Hole Pairs Generated in the Crystalline Phase of Polymer Diodes Studied by Electrically Detected Magnetic Resonance Techniques

Iwamoto¹,

Hayakawa²,

Hatanaka³

et al. 2019

J. Phys. Chem. C

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The properties of electron−hole (e−h) pairs generated in a working poly(3-hexylthiophene) (P3HT) diode are investigated by electrically detected magnetic resonance (EDMR) techniques. The EDMR intensity is shown to increase with increasing density of injected electrons for a given hole density, demonstrating that the EDMR signal arises from an e−h pair. The EDMR spectrum consists of two Gaussian curves, one of which gives a g-value very similar to that of hole carriers, suggesting that the EDMR spectrum is given by the sum of electron spin resonance (ESR) spectra from hole and electron carriers forming e−h pairs. Bias-dependent correlation between carriers and e−h pairs under diode operation is examined directly from independent measurements of near-infrared (NIR) spectroscopy for carriers and EDMR for e−h pairs. When the bias is increased to above a threshold, the EDMR signal is strongly reduced despite a gradual increase in the NIR signals, providing evidence that the e−h pairs are dissociated by an electric field in the bias region. Because of this property of the pair, the correlation between the carriers and e−h pairs inside the diode changes depending on the bias magnitude: the carriers and e−h pairs coexist or only the carriers exist. The e−h pair is presumed to be formed across different lamellae because of the crystalline phase of the P3HT film. Although the intensity of the EDMR signal from the interlamellar e−h pair is small, the intensity increases substantially when the sample is exposed to air, suggesting the formation of a magnetoreactive species that incorporates oxygen.

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“…By far, PEC stability is still a very challenging issue for polymer BHJ-based photocathodes. − To identify the factors that affect the PEC stability, controlled experiments over the photocathode samples with comparable PEC activities were performed under different conditions. The LSV curves before and after post treatments are recorded in Figure a and the onset potential and photocurrent density at 0 V are summarized in Table S3 for comparison.…”

Section: Resultsmentioning

confidence: 99%

PTB7:PC₆₁BM Bulk Heterojunction-Based Photocathodes for Efficient Hydrogen Production in Aqueous Solution

Shi

Deng

et al. 2019

Chem. Mater.

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Because of excellent light absorption and charge separation properties, a polymer bulk heterojunction (BHJ) composed of electron−donor and electron−acceptor is very promising to be used for photoelectrode preparation. In this work, a PTB7:PC 61 BM BHJbased photocathode is fabricated for photoelectrochemical (PEC) hydrogen evolution reaction (HER) in aqueous solution. With CuO x and TiO x thin films as interfacial modification layers, the photocathode with full structure (fluorine-doped tin oxide/CuO x /PTB7:PC 61 BM/ TiO x /Pt) generates a maximum photocurrent density up to −7.27 mA cm −2 and an onset potential as positive as 0.63 V. The half-cell solar-tohydrogen efficiency is up to 1.5%, outperforming all of the previous BHJbased photocathodes for HER. CuO x is identified to play a role of facilitating charge separation, whereas TiO x improves the charge injection as well as blocks the back migration of holes during the PEC process. The factors including permeation of water and oxygen molecules, incident light spectrum, and current flowing that affect the PEC stability are investigated and discussed.

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Air exposure induced recombination in PTB7:PC₇₁BM solar cells

Abstract: Magnetic resonance identifies oxidised PC71BM recombination centres in PTB7:PC71BM solar cells processed when using DIO and exposed to air.

Cited by 9 publications

References 55 publications

Calamitic-Type Dipolar and Quadrupolar Chromophores with a Twisted Peripheral Handle: Structure–Property Outlook as Nonfullerene Acceptors for Binary Solar Cells

Calamitic-Type Dipolar and Quadrupolar Chromophores with a Twisted Peripheral Handle: Structure–Property Outlook as Nonfullerene Acceptors for Binary Solar Cells

Electron–Hole Pairs Generated in the Crystalline Phase of Polymer Diodes Studied by Electrically Detected Magnetic Resonance Techniques

PTB7:PC₆₁BM Bulk Heterojunction-Based Photocathodes for Efficient Hydrogen Production in Aqueous Solution

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Air exposure induced recombination in PTB7:PC71BM solar cells

Abstract: Magnetic resonance identifies oxidised PC71BM recombination centres in PTB7:PC71BM solar cells processed when using DIO and exposed to air.

Cited by 9 publications

References 55 publications

Calamitic-Type Dipolar and Quadrupolar Chromophores with a Twisted Peripheral Handle: Structure–Property Outlook as Nonfullerene Acceptors for Binary Solar Cells

Calamitic-Type Dipolar and Quadrupolar Chromophores with a Twisted Peripheral Handle: Structure–Property Outlook as Nonfullerene Acceptors for Binary Solar Cells

Electron–Hole Pairs Generated in the Crystalline Phase of Polymer Diodes Studied by Electrically Detected Magnetic Resonance Techniques

PTB7:PC61BM Bulk Heterojunction-Based Photocathodes for Efficient Hydrogen Production in Aqueous Solution

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Air exposure induced recombination in PTB7:PC₇₁BM solar cells

PTB7:PC₆₁BM Bulk Heterojunction-Based Photocathodes for Efficient Hydrogen Production in Aqueous Solution