New insights into polymer solar cells stability: The crucial role of PCBM oxidation

Perthué, Anthony; Gorisse, Thérèse; Silva, Hugo Santos; Lombard, Christian; Bégué, Didier; Hudhomme, Piétrick; Pépin-Donat, Brigitte; Rivaton, Agnès; Wantz, Guillaume

doi:10.1557/jmr.2018.141

Cited by 17 publications

(17 citation statements)

References 45 publications

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“…If light-induced, these species can accumulate as a result of prolonged illumination, particularly in case of pulsed laser excitation with its high energy densities. These stable paramagnetic defects can be probed by conventional cw-EPR (Frolova et al, 2015; Susarova et al, 2015) and further characterized using pulsed EPR spectroscopy, their effects on the devices probed using LEPR spectroscopy (Havlicek et al, 2018; Perthué et al, 2018).…”

Section: Paramagnetic States In Organic Photovoltaic Devicesmentioning

confidence: 99%

Structure–Function Relationship of Organic Semiconductors: Detailed Insights From Time-Resolved EPR Spectroscopy

Biskup

2019

Front. Chem.

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Organic photovoltaics (OPV) is a promising technology to account for the increasing demand for energy in form of electricity. Whereas the last decades have seen tremendous progress in the field witnessed by the steady increase in efficiency of OPV devices, we still lack proper understanding of fundamental aspects of light-energy conversion, demanding for systematic investigation on a fundamental level. A detailed understanding of the electronic structure of semiconducting polymers and their building blocks is essential to develop efficient materials for organic electronics. Illuminating conjugated polymers not only leads to excited states, but sheds light on some of the most important aspects of device efficiency in organic electronics as well. The interplay between electronic structure, morphology, flexibility, and local ordering, while at the heart of structure—function relationship of organic electronic materials, is still barely understood. (Time-resolved) electron paramagnetic resonance (EPR) spectroscopy is particularly suited to address these questions, allowing one to directly detect paramagnetic states and to reveal their spin-multiplicity, besides its clearly superior spectral resolution compared to optical methods. This article aims at giving a non-specialist audience an overview of what EPR spectroscopy and particularly its time-resolved variant (TREPR) can contribute to unraveling aspects of structure–function relationship in organic semiconductors.

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Section: Paramagnetic States In Organic Photovoltaic Devicesmentioning

confidence: 99%

Structure–Function Relationship of Organic Semiconductors: Detailed Insights From Time-Resolved EPR Spectroscopy

Biskup

2019

Front. Chem.

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“…The combination of both can cause changes in morphology 9–10 and energy levels, leading to a lower efficiency. The interaction of oxygen and water with P3HT can, for example, cause a loss of alkyl and thiophene groups, 11 whereas PCBM can undergo dimerization, 12–14 or oxidation of the fullerene group 15–16 . In both cases, this leads to a decrease in aromaticity and conjugation length and, therefore, a decrease in light absorbance and, ultimately, performance efficiency.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale chemical analysis of beam‐sensitive polymeric materials by cryogenic electron microscopy

Wirix

Lazar

Verhoeven

et al. 2021

Journal of Polymer Science

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Nanoscale chemical analysis of functional polymer systems by electron microscopy, to gain access into degradation processes during the materials life cycle, is still a formidable challenge due to their beam sensitivity. Here a systematic study on the different stages of degradation in a P3HT‐PCBM organic photovoltaic (OPV) model system is presented. To this end pristine samples, samples with (reversibly) physisorbed oxygen and water and samples with (irreversibly) chemisorbed oxygen and water are imaged utilizing the full capabilities of cryogenic STEM‐EELS. It is found that oxygen and water are largely physisorbed in this system leading to significant effects on the band structure, especially for PCBM. Quantification proves that degradation concomitantly decreases the amount of CC bonds and increases the amount of COC bonds in the sample. Finally, it is shown that with a pulsed electron beam utilizing a microwave cavity, beam damage can be significantly reduced which likely extends the possibilities for such studies in future.

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“…Foremost of all, fullerene acceptors are usually the main factor limiting the device lifetime. The most used derivatives PC 60 BM and PC 70 BM have been reported to dimerize or degrade upon exposure to oxygen and light, which limits device performance due to trap formation or a reduction in electron mobility . Therefore, investigating strategies to suppress the degradation in fullerene‐based organic solar cells is imperative for future utilization of such devices.…”

Section: Introductionmentioning

confidence: 99%

Energy Transfer to a Stable Donor Suppresses Degradation in Organic Solar Cells

Weu

Kumar

Butscher

et al. 2019

Adv Funct Materials

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Despite many advances toward improving the stability of organic photovoltaic devices, environmental degradation under ambient conditions remains a challenging obstacle for future application. Particularly conventional systems employing fullerene derivatives are prone to oxidize under illumination, limiting their applicability. Here, the environmental stability of the small molecule donor DRCN5T together with the fullerene acceptor PC 70 BM is reported. It is found that this system exhibits exceptional device stability, mainly due to almost constant short-circuit current. By employing ultrafast femtosecond transient absorption spectroscopy, this remarkable stability is attributed to two separate mechanisms: 1) DRCN5T exhibits high intrinsic resistance toward external factors, showing no signs of deterioration.2) The highly sensitive PC 70 BM is stabilized against degradation by the presence of DRCN5T through ultrafast, long-range energy transfer to the donor, rapidly quenching the fullerene excited states which are otherwise precursors for chemical oxidation. It is proposed that this photoprotective mechanism be utilized to improve the device stability of other systems, including nonfullerene acceptors and ternary blends.

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New insights into polymer solar cells stability: The crucial role of PCBM oxidation

Abstract: Abstract

Cited by 17 publications

References 45 publications

Structure–Function Relationship of Organic Semiconductors: Detailed Insights From Time-Resolved EPR Spectroscopy

Structure–Function Relationship of Organic Semiconductors: Detailed Insights From Time-Resolved EPR Spectroscopy

Nanoscale chemical analysis of beam‐sensitive polymeric materials by cryogenic electron microscopy

Energy Transfer to a Stable Donor Suppresses Degradation in Organic Solar Cells

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