Bimolecular and Trap‐Assisted Recombination in Organic Bulk Heterojunction Solar Cells

Wetzelaer, Gert‐Jan A. H.; Koster, L. Jan Anton; Blom, Paul W. M.

doi:10.1002/9783527656912.ch11

Cited by 6 publications

(9 citation statements)

References 75 publications

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“…A larger n indicates a more pronounced Shockley-Read-Hall (SRH) recombination. [62,63] We obtained n = 1.32 for OSCs with neat P3HT:ICBA lightharvesting layers, which is in accordance with earlier literature reports. [64] Upon addition of F 4 TCNQ, n gradually increases up to 1.73 (w F TCNQ 4 = 0.4 wt%), hence indicating enhanced SRH recombination, which agrees well with the reduction of the V OC and the fill factor toward higher doping ratios.…”

Section: Solar Cells Fabricated From Electrically Doped P3ht:icba Nan...supporting

confidence: 92%

Organic Solar Cells: Electrostatic Stabilization of Organic Semiconductor Nanoparticle Dispersions by Electrical Doping

Manger

Marlow

Fischer

et al. 2022

Adv Funct Materials

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Organic semiconductor nanoparticle dispersions are electrostatically stabilized with the p‐doping agent 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ), omitting the need for surfactants. Smallest amounts of F4TCNQ stabilize poly(3‐hexylthiophene) dispersions and reduce the size of the nanoparticles significantly. The concept is then readily transferred to synthesize dispersions from a choice of light‐harvesting benzodithiophene‐based copolymers. Dispersions from the corresponding polymer:fullerene blends are used to fabricate organic solar cells (OSCs). In contrast to the widely used stabilizing surfactants, small amounts of F4TCNQ show no detrimental effect on the device performance. This concept paves the way for the eco‐friendly fabrication of OSCs from nanoparticle dispersions of high‐efficiency light‐harvesting semiconductors by eliminating environmentally hazardous solvents from the deposition process.

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Section: Solar Cells Fabricated From Electrically Doped P3ht:icba Nan...supporting

confidence: 92%

Organic Solar Cells: Electrostatic Stabilization of Organic Semiconductor Nanoparticle Dispersions by Electrical Doping

Manger

Marlow

Fischer

et al. 2022

Adv Funct Materials

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“…However, as the V eff decreases, the P CC starts to diminish much quicker in degraded samples. When free charges stay longer inside the device before collection, the influence of deep energetic traps and morphological changes related to charge transport will then be amplified. ,− This is in agreement with the changes in series ( R S ) and shunt ( R Sh ) resistances (Figure e), which are highly dependent on film morphology; − values are obtained from the slopes of J–V curves. − Furthermore, a considerable increase in the surface roughness, measured through AFM (Figure a–d), and a decrease in the line width of the Raman vibration assigned to C–C stretches (Figure S7) were found after degradation. In addition, the interconnected multiscale chains of PM6:BTP-4Cl (Figure S8), compared to the more globular-shaped chains of PM6:IT-4Cl, can be observed and are believed to contribute to better thermal stability, − consistent with the lower degradation losses of PM6:BTP-4Cl.…”

supporting

confidence: 64%

“…Light-intensity-dependent measurements, shown in Figure e,f, were performed and analyzed based on previous reports − ,, to understand how morphological changes affected the solar cell performance. The constant (α) from the power law relation, J SC = ( P in ) α , describes the short-circuit monomolecular recombination and was found to be similar in nondegraded and degraded samples, thus illustrating consistency with the obtained J SC and EQE .…”

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confidence: 99%

Understanding the Charge Transfer State and Energy Loss Trade-offs in Non-fullerene-Based Organic Solar Cells

et al. 2021

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Energy losses significantly reduce the open-circuit voltage among current state-of-the-art organic solar cells (OSCs), which limits the further enhancement of their power conversion efficiencies (PCEs). In this study, the bulk heterojunction blends of PM6 donor and halogenated nonfullerene acceptors (NFAs) display a trade-off between radiative energy losses, i.e., charge transfer state (CTS) radiative energy loss (ΔE rad ) and the loss associated with CTS formation from acceptor singlet excitons (ΔE CT EL ). Similarly, a trade-off between ΔE rad and the nonradiative energy loss (ΔE nr ) is found, reflecting a competition in radiative and nonradiative charge recombination pathways. Further, the energy levels of relaxed CTS (E CT EL ) are shown to exhibit dependence on morphologically induced energetic traps, suggesting that it should not be associated merely to blend constituents. Interestingly, these correlations extend even to thermally degraded devices considered herein. Accordingly, this work provides further understandings of energy losses relevant to overcome the current limitations concerning NFA-based OSC developments.

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“…Meanwhile, PEIE‐EDT with a slope of 1.11 kT / q has less dependency on the light intensity indicating the suppressed trap‐assisted recombination. [ 34 , 36 , 37 ]…”

Section: Resultsmentioning

confidence: 99%

Mitigating the Undesirable Chemical Reaction between Organic Molecules for Highly Efficient Flexible Organic Photovoltaics

et al. 2021

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Organic photovoltaics (OPVs) with nonfullerene acceptors (NFAs) feature excellent device performance and device stability. However, they are facing problems when the amine-rich polyelectrolytes are used as cathode interfacial layers. In this work, a small molecule, ethanedithiol (EDT) at the polyethyleneimine ethoxylated (PEIE)/active layer interface is inserted for mitigating the undesirable reaction between amine-rich groups and electron-acceptor moieties in NFA. The main role of EDT is to passivate the PEIE surface and prevent electron flow to NFA and the unwanted reaction can be mitigated. It improves the performance of OPV devices by reducing the work function, decreasing trap-assisted recombination, and improving electron-mobility. As a result, the flexible device with the PEIE interfacial layer with a power conversion efficiency (PCE) of 7.20% can be improved to 10.11% after the inclusion of EDT. Moreover, EDT-modified device can retain 98.18% after it is bent for 200 cycles and can maintain 80.83% of its initial PCE under continuous light illuminated in ambient conditions without any encapsulation. Based on these findings, the proposed strategy constitutes a crucial step toward highly efficient flexible OPVs.

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Bimolecular and Trap‐Assisted Recombination in Organic Bulk Heterojunction Solar Cells

Cited by 6 publications

References 75 publications

Organic Solar Cells: Electrostatic Stabilization of Organic Semiconductor Nanoparticle Dispersions by Electrical Doping

Organic Solar Cells: Electrostatic Stabilization of Organic Semiconductor Nanoparticle Dispersions by Electrical Doping

Understanding the Charge Transfer State and Energy Loss Trade-offs in Non-fullerene-Based Organic Solar Cells

Mitigating the Undesirable Chemical Reaction between Organic Molecules for Highly Efficient Flexible Organic Photovoltaics

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