In-Operando Study of the Effects of Solvent Additives on the Stability of Organic Solar Cells Based on PTB7-Th:PC<sub>71</sub>BM

Yang, Dan; Löhrer, Franziska C.; Körstgens, Volker; Schreiber, Armin; Bernstorff, Sigrid; Buriak, Jillian M.; Müller‐Buschbaum, Peter

doi:10.1021/acsenergylett.8b02311

Cited by 64 publications

(62 citation statements)

References 61 publications

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“…However, physical degradation with morphological changes in the active layer occurs even in the absence of reactive molecules as shown for several materials . So far, two major pathways of the morphological degradation were identified: Starting from an optimized morphology of the BHJ, either a demixing‐induced coarsening of the domains or mixing‐induced shrinkage of the domains was identified . Domain coarsening in combination with an increase in distances between neighboring domains resulted in a decrease in the short‐circuit current density ( J SC ) during device degradation as first identified for the model system poly(3‐hexylthiophene) (P3HT) and phenyl‐C61‐butyric acid methyl ester (PCBM) .…”

Section: Introductionmentioning

confidence: 99%

“…To overcome the challenge of upscaling the thin‐film deposition, promising techniques, such as spraying, inkjet printing, and meniscus‐guided slot‐die coating, are introduced in the field of organic photovoltaics . Even though the stability of organic solar cells could be improved successfully by the synthesis of new materials, end‐group and side‐chain modification, or the development of an inverted device structure, the poor long‐term stability of most high‐efficiency materials has to be further improved for a commercial breakthrough . Therefore, understanding the degradation mechanism of printed bulk‐heterojunction (BHJ) photovoltaics is essential to realize the production of large‐area organic solar cells with outstanding PCE and excellent long‐term stability.…”

Section: Introductionmentioning

confidence: 99%

“…The chemical degradation of organic solar cells in the presence of water or oxygen has been studied for many materials and can be avoided by proper encapsulation of the devices . However, physical degradation with morphological changes in the active layer occurs even in the absence of reactive molecules as shown for several materials . So far, two major pathways of the morphological degradation were identified: Starting from an optimized morphology of the BHJ, either a demixing‐induced coarsening of the domains or mixing‐induced shrinkage of the domains was identified .…”

Section: Introductionmentioning

confidence: 99%

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Following in Operando the Structure Evolution‐Induced Degradation in Printed Organic Solar Cells with Nonfullerene Small Molecule Acceptor

et al. 2020

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Understanding the degradation mechanisms of printed bulk‐heterojunction (BHJ) organic solar cells during operation is essential to achieve long‐term stability and realize real‐world applications of organic photovoltaics. Herein, the degradation of printed organic solar cells based on the conjugated benzodithiophene polymer PBDB‐T‐SF and the nonfullerene small molecule acceptor IT‐4F with 0.25 vol% 1,8‐diiodooctane (DIO) solvent additive is studied in operando for two different donor:acceptor ratios. The inner nano‐morphology is analyzed with grazing incidence small angle X‐ray scattering (GISAXS), and current–voltage (I–V) characteristics are probed simultaneously. Irrespective of the mixing ratio, degradation occurs by the same degradation mechanism. A decrease in the short‐circuit current density (JSC) is identified to be the determining factor for the decline of the power conversion efficiency. The decrease in JSC is induced by a reduction of the relative interface area between the conjugated polymer and the small molecule acceptor in the BHJ structure, resembling the morphological degradation of the active layer.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Following in Operando the Structure Evolution‐Induced Degradation in Printed Organic Solar Cells with Nonfullerene Small Molecule Acceptor

et al. 2020

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“…However, it is still necessary to improve photovoltaic performances in PSCs for commercial applications. The main limiting factors for the performance of PSCs are the narrow spectral response range of the organic active layer materials and the degradation of polymers [7][8][9]. As the spectral response range of polymer solar cells is mainly in the visible light region, the solar cells cannot effectively utilize solar radiation in the ultraviolet (UV) and infrared (IR) regions [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…As the spectral response range of polymer solar cells is mainly in the visible light region, the solar cells cannot effectively utilize solar radiation in the ultraviolet (UV) and infrared (IR) regions [10,11]. In addition, the degradation of polymers under the action of ultraviolet rays and additives causes the photovoltaic performance of organic cells to decline, which limits the conversion efficiency of PSCs [9,[12][13][14][15][16]. To solve those problems, researchers have used different fabrication methods to increase the spectral response range of PSCs; different donor materials with complementary light absorptions were applied to tandem solar cells and a ternary device with two complementary absorptions donors and one acceptor has been used [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Hybrid ZnO Electron Transport Layer by Down Conversion Complexes for Dual Improvements of Photovoltaic and Stable Performances in Polymer Solar Cells

Shen

Zhang

et al. 2020

Nanomaterials

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Polymer solar cells (PSCs) have shown excellent photovoltaic performance, however, extending the spectral response range to the ultraviolet (UV) region and enhancing the UV light stability remain two challenges to overcome in the development of PSCs. Lanthanide down-conversion materials can absorb the UV light and re-emit it at the visible region that matches well with the absorption of the active layer material PTB7-Th (poly[[2,6′-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b]dithiophene][3-fluoro-2[(2-ethylhexyl)carbony]thieno[3,4-b]thiophenediyl]]) and PBDB-T-2F, thus helping to enhance the photovoltaic performance and UV light stability of PSCs. In this research, a down-conversion material Eu(TTA)3phen (ETP) is introduced into the cathode transport layer (ZnO) in PSCs to manipulate its nanostructure morphology for its application in hyperfine structure of PSCs. The device based on the ZnO/ETP electron transport layer can obtain power conversion efficiencies (PCEs) of 9.22% (PTB7-Th–PC71BM ([6,6]-phenylC71-butyric acid methyl ester) device) and 13.12% (PBDB-T-2F–IT-4F device), respectively. Besides, in the research on PTB7-Th-PC71BM device, the stability of the device based on ZnO/ETP layer is prolonged by 70% compared with the ZnO device. The results suggest that the ZnO/ETP layer plays the role of enhanced photovoltaic performance and prolonged device stability, as well as reducing photo-loss and UV degradation for PSCs.

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Progress in Materials, Solution Processes, and Long‐Term Stability for Large‐Area Organic Photovoltaics

et al. 2020

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processing at low cost compared with their inorganic counterparts. The first breakthrough in OPV technology was achieved by realizing BHJ active layers with nanoscale bicontinuous network structures of electron donor (D) and acceptor (A) materials; this structure enables efficient exciton separation at the D-A interface. [1] The development of push-pull-type donor polymers has effectively extended the light absorption range of OPVs into the near-infrared (NIR) region, which has ultimately led to substantial improvements in power conversion efficiency (PCE) to greater than 10%. In particular, highly crystalline donor polymers such as PffBT4T-2OD substantially improved charge-transport properties, enabling OPV devices with a BHJ film thickness greater than 200 nm to operate. [2] Historically, fullerene derivatives have been dominantly used as acceptors in OPVs because of their excellent electron-accepting and transporting properties and because they can be prepared with a morphology optimized for efficient charge-carrier generation and transport. [3,4] However, despite such promising characteristics, OPVs based on fullerene derivatives have drawbacks of limited light-absorption properties, poor energylevel tunability, and poor morphological and/or photochemical stability. [5,6] Over the past several years, tremendous efforts have been directed toward the development of nonfullerenebased OPVs to overcome these limitations. The advantages of nonfullerene acceptors over fullerenes include easily tunable energy levels, which enables OPVs to achieve substantially higher open-circuit voltages (V OC s) than conventional fullerenebased devices. [7] In addition, nonfullerene acceptors enable better light absorption properties and therefore generate higher photocurrents than fullerene derivatives. [8] Furthermore, nonfullerene acceptors with appropriate molecular tailoring can provide chemically stable photoactive materials, potentially enhancing long-term device stability. [5] Recent breakthroughs realized through the development of small molecular nonfullerene acceptors have resulted in remarkable enhancements in the PCEs of single-junction OPVs to greater than 17%, which demonstrates the potential for the large-scale manufacture of OPVs. [9] When translating photovoltaic technology from laboratory to commercial products, low cost, high PCE, and high Organic solar cells based on bulk heterojunctions (BHJs) are attractive energy-conversion devices that can generate electricity from absorbed sunlight by dissociating excitons and collecting charge carriers. Recent breakthroughs attained by development of nonfullerene acceptors result in significant enhancement in power conversion efficiency (PCEs) exceeding 17%. However, most of researches have focused on pursuing high efficiency of small-area (<1 cm 2) unit cells fabricated usually with spin coating. For practical application of organic photovoltaics (OPVs) from lab-scale unit cells to industrial products, it is essential to develop efficient technologies that can extend act...

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In-Operando Study of the Effects of Solvent Additives on the Stability of Organic Solar Cells Based on PTB7-Th:PC₇₁BM

Cited by 64 publications

References 61 publications

Following in Operando the Structure Evolution‐Induced Degradation in Printed Organic Solar Cells with Nonfullerene Small Molecule Acceptor

Following in Operando the Structure Evolution‐Induced Degradation in Printed Organic Solar Cells with Nonfullerene Small Molecule Acceptor

Hybrid ZnO Electron Transport Layer by Down Conversion Complexes for Dual Improvements of Photovoltaic and Stable Performances in Polymer Solar Cells

Progress in Materials, Solution Processes, and Long‐Term Stability for Large‐Area Organic Photovoltaics

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In-Operando Study of the Effects of Solvent Additives on the Stability of Organic Solar Cells Based on PTB7-Th:PC71BM

Cited by 64 publications

References 61 publications

Following in Operando the Structure Evolution‐Induced Degradation in Printed Organic Solar Cells with Nonfullerene Small Molecule Acceptor

Following in Operando the Structure Evolution‐Induced Degradation in Printed Organic Solar Cells with Nonfullerene Small Molecule Acceptor

Hybrid ZnO Electron Transport Layer by Down Conversion Complexes for Dual Improvements of Photovoltaic and Stable Performances in Polymer Solar Cells

Progress in Materials, Solution Processes, and Long‐Term Stability for Large‐Area Organic Photovoltaics

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In-Operando Study of the Effects of Solvent Additives on the Stability of Organic Solar Cells Based on PTB7-Th:PC₇₁BM