Long-Term Stabilization of Organic Solar Cells Using Hindered Phenols as Additives

Turkovic, Vida; Engmann, Sebastian; Tsierkezos, Nikos G.; Hoppe, Harald; Ritter, Uwe; Gobsch, G.

doi:10.1021/am5024989

Cited by 47 publications

(36 citation statements)

References 65 publications

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“…Elegant device optimization has been developed such as solvent additive processing, vapor annealing, and thermal annealing treatment within thin active layers. Solvent additives have been proved to be more prone to influence the stability and reproducibility of the devices . In particular, the compatibility of high‐efficiency value and thick blend film is a major challenge as normally the most of the highly efficient OSCs provided their optimal performance with photoactive layer thickness of ≈100 nm .…”

Section: Introductionmentioning

confidence: 99%

Molecular Orientation Unified Nonfullerene Acceptor Enabling 14% Efficiency As‐Cast Organic Solar Cells

Feng

Song

Zhang

et al. 2019

Adv Funct Materials

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Molecular orientation and π-π stacking of nonfullerene acceptors (NFAs) determine its domain size and purity in bulk-heterojunction blends with a polymer donor. Two novel NFAs featuring an indacenobis(dithieno[3,2-b:2′,3′-d] pyrrol) core with meta-or para-alkoxyphenyl sidechains are designed and denoted as m-INPOIC or p-INPOIC, respectively. The impact of the alkoxyl group positioning on molecular orientation and photovoltaic performance of NFAs is revealed through a comparison study with the counterpart (INPIC-4F) bearing para-alkylphenyl sidechains. With inward constriction toward the conjugated backbone, m-INPOIC presents predominant face-on orientation to promote charge transport. The as-cast organic solar cells (OSCs) by blending m-INPOIC and PBDB-T as active layers exhibit a power conversion efficiency (PCE) of 12.1%. By introducing PC 71 BM as the solid processing-aid, the ternary OSCs are further optimized to deliver an impressive PCE of 14.0%, which is among the highest PCEs for as-cast single-junction OSCs reported in literature to date. More attractively, PBDB-T:m-INPOIC:PC 71 BM based OSCs exhibit over 11% PCEs even with an active layer thickness over 300 nm. And the devices can retain over 95% of PCE after storage for 20 days. The outstanding tolerance to film thickness and outstanding stability of the as-cast devices make m-INPOIC a promising candidate NFA for large-scale solutionprocessable OSCs.

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Section: Introductionmentioning

confidence: 99%

Molecular Orientation Unified Nonfullerene Acceptor Enabling 14% Efficiency As‐Cast Organic Solar Cells

Feng

Song

Zhang

et al. 2019

Adv Funct Materials

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“…Previously, Turkovic et al observed polymer-selective stabilizing effects of antioxidants in blends of the model system P3HT:PCBM. [9][10][11] P3HT, however, can be considered an unusual exception, given that in the presence of the radical scavenging fullerene PCBM, it is rather inert towards reactive oxygen species. 12 This is in contrast to many other structurally more complex, high performance polymers, whose aging kinetics has been closely linked to the presence of reactive oxygen species.…”

Section: Introductionmentioning

confidence: 99%

Suppressing photooxidation of conjugated polymers and their blends with fullerenes through nickel chelates

Salvador

Gasparini

Perea

et al. 2017

Energy Environ. Sci.

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Conjugated polymer semiconductors offer unique advantages over conventional semiconductors but tend to suffer from electro-optic performance roll-off, mainly due to reduced photofastness. Here, we demonstrate that the commodity nickel chelate nickel(II) dibutyldithiocarbamate, Ni(dtc) 2 , effectively inhibits photooxidation across a wide range of prototypical p-conjugated polymer semiconductors and blends. The addition of 2-10 wt% of Ni(dtc) 2 increases the resilience of otherwise quickly photobleaching semiconducting thin films, even in the presence of detrimental, radical forming processing additives. Using electron spin resonance spectroscopy and sensitive oxygen probes, we found that Ni(dtc) 2 acts as a broadband stabilizer that inhibits both the formation of reactive radicals and singlet oxygen. The mechanism of stabilization is of sacrificial nature, but contains non-sacrificial contributions in polymers where singlet oxygen is a key driver of photooxidation. Ultrafast pump-probe spectroscopy reveals quenching of triplet excited states as the central mechanism of non-sacrificial stabilization. When introduced into the active layer of organic photovoltaic devices, Ni(dtc) 2 retards the short circuit current loss in air without affecting the sensitive morphology of bulk heterojunctions and without major sacrifices in semiconductor properties. Antioxidants based on nickel complexes thus constitute functional stabilizers for elucidating degradation mechanisms in organic semiconductors and represent a cost-effective route toward organic electronic appliances with extended longevity. Broader contextOrganic semiconductors based on conjugated polymers bear exceptional opportunities for many disruptive technologies, including light and power generation, sensor technology and electronic circuitry, which could potentially be realized in a sustainable fashion using highly efficient and low-cost approaches. However, conjugated polymers suffer from photo-oxidation-induced performance loss and need to be carefully encapsulated, compromising both applicability and cost benefits. In the present work, we introduce a nickel chelate, nickel(II) dibutyldithiocarbamate, as a universal antioxidant for increasing the longevity of conjugated polymers. We carried out a mechanistic study that quantitatively describes the stabilization of conjugated polymer moieties with technological relevance for OLEDs, OPVs and OFETs. We introduce for the first time a figure of merit (FOM) as a stabilization metric for antioxidants in conjugated polymers. This FOM serves likewise to distinguish between sacrificial and non-sacrificial protective mechanisms. We draw wide ranging conclusions that reflect on how conjugated polymer and polymer:fullerene blends photo-oxidize and how the underlying mechanisms can be significantly suppressed in the presence of nickel chelates. Finally, we demonstrate its beneficial use in a broad range of organic photovoltaic devices.

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“…Contrary to T cont 80 B 1 h, which ignores the recovery processes, T max 80 (B4 d) accounts for irreversible losses and/or incomplete recovery during one night. However, it does not account for the dynamics of the diurnal degradation, and therefore, it can lead to a misleading conclusion in terms of the total energy generated by the cell during its lifetime: [13][14][15] E…”

mentioning

confidence: 99%

Reconsidering figures of merit for performance and stability of perovskite photovoltaics

Khenkin

Anoop

Visoly‐Fisher

et al. 2018

Energy Environ. Sci.

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Long-Term Stabilization of Organic Solar Cells Using Hindered Phenols as Additives

Cited by 47 publications

References 65 publications

Molecular Orientation Unified Nonfullerene Acceptor Enabling 14% Efficiency As‐Cast Organic Solar Cells

Molecular Orientation Unified Nonfullerene Acceptor Enabling 14% Efficiency As‐Cast Organic Solar Cells

Suppressing photooxidation of conjugated polymers and their blends with fullerenes through nickel chelates

Reconsidering figures of merit for performance and stability of perovskite photovoltaics

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