The effect of a concentration graded cathode for organic solar cells

Jeon, Jae Ho; Lee, Hang Ken; Wang, Dong Hwan; Park, Soon Mi; Kim, Jeong Won; Kim, Kyung Joong; Park, Jae Hyung; Park, O Ok

doi:10.1016/j.solmat.2011.04.026

Cited by 8 publications

(6 citation statements)

References 22 publications

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“…The cathode interface has also been investigated in a variety of alternative OPV systems by several other groups using SIMS-based analysis. 268,269 Ellipsometry, a non-destructive and contactless optical technique based on the measurement of material dielectric properties, has also been applied in vertical morphology studies, where it contributed to some of the earliest reports that the cathode-active layer interface in P3HT-PC 61 BM solar cells is enriched in P3HT. 270 Perhaps the most significant concern with the use of SIMS for morphology characterization of soft matter systems such as OPVs is unpredictable sputter damage caused by the high-energy ion beam, which is most commonly comprised of Cs + ions.…”

Section: Additional Techniquesmentioning

confidence: 99%

Morphology characterization in organic and hybrid solar cells

Chen

Nikiforov

Darling

2012

Energy Environ. Sci.

395

430

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Organic and hybrid organic-inorganic photovoltaics are among the most promising options for lowcost and highly scalable renewable energy. In order to fully realize the potential of these technologies, power conversion efficiencies and stability will both have to be improved beyond the current state-ofthe-art. The morphology of the active layer is of paramount importance in the photon to electron conversion process in organic and hybrid solar cells, with all length scales, from molecular ordering to intradevice composition variability, playing key roles. Given the central influence of morphology, characterizing the structure of these surprisingly complex material systems at multiple length scales is one of the grand challenges in the field. This review addresses the techniques, some of which have only recently been applied to organic and hybrid photovoltaics, available to scientists and engineers working to understand-and ultimately improve-the operation of these fascinating devices.

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Section: Additional Techniquesmentioning

confidence: 99%

Morphology characterization in organic and hybrid solar cells

Chen

Nikiforov

Darling

2012

Energy Environ. Sci.

395

430

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“…These segregations are attributed to the difference in surface free energy between P3HT and PCBM, as revealed in previous studies. [8][9][10] The localized reduction of P3HT in the bulk center was exhibited only in the spin-cast films. The spinning process is thus considered to be the cause of this localized reduction.…”

Section: Morphology Formation By Spin-casting Mechanismmentioning

confidence: 99%

“…3) Various methods have been proposed for controlling the BHJ morphology and thereby improving the performance of PSCs. They include thermal annealing, [4][5][6][7][8][9][10][11] solvent annealing, 12,13) slow drying, 14) and the use of additives. 15) P-type poly(3-hexylthiophene) (P3HT) and n-type fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) are two conventional materials that are widely used in PSCs.…”

Section: Introductionmentioning

confidence: 99%

“…Cells treated by post-annealing generally show better performance. 5,[8][9][10] Several mechanisms have been proposed for explaining the effect of thermal annealing, including improved crystallinity of the organic layers, 6,7) segregation at the cathode interface, [8][9][10] and changes in the phase-separated morphology. 11) Among these candidate mechanisms, the effect of changes in organic crystallinity has been the most frequently reported.…”

Section: Introductionmentioning

confidence: 99%

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Thermally induced vertical phase separation and photovoltaic characteristics of polymer solar cells for P3HT/PCBM composites

Nagai

Huang

Yoshida

2016

Jpn. J. Appl. Phys.

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The occurrence of vertical phase separation has been reported for various spin-cast polymer films, including bulk-heterojunction films of polymer solar cells (PSCs). Focusing on real-space analysis, we conducted a study on the relationship between the morphology and processing conditions of PSCs for typical poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) cells. Our results demonstrated that spin-casting caused a localized reduction in the P3HT concentration in the bulk center. Thermal annealing after cathode formation enhanced the unevenness in concentration and created a multilayered vertical phase-separated morphology in which the P3HT domains were gathered near the electrodes, leaving only PCBM domains at the center of the film. Cells with this morphology had good power conversion efficiency (∼3%).

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“…Various studies have been performed to estimate the lifetime of P3HT/PCBM BHJs based on such conventional OPV device structures, reporting lifetimes of up to ~600–700 h for encapsulated devices . The degradation of the P3HT/PCBM solar cells has been specifically attributed to factors such as photodegradation of the active layer , degradation of P3HT due to the presence of PCBM , phase separation of PEDOT/PSS layer , and interdiffusion of mobile ions across and into the active layer . While many of these findings suggest intrinsic chemical instability associated with the BHJ, it is also apparent that finding a suitable PEDOT/PSS replacement is necessary to improve device lifetimes.…”

Section: Introductionmentioning

confidence: 99%

Improved lifetimes of organic solar cells with solution‐processed molybdenum oxide anode‐modifying layers

Garg

Gupta

Jasieniak

et al. 2014

Progress in Photovoltaics

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We report on the use and stability of solution‐processed molybdenum oxide (sMoOx) thin films as anode‐modifying layers to replace conventionally used poly(3,4‐ethyldioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) layers in poly(3‐hexylthiophene):[6,6]‐phenyl C61 butyric acid methyl ester (P3HT/PC61BM) bulk heterojunction organic solar cells. Our results show that while as prepared devices using the two anode‐modifying layers possess similar performances, the sMoOx devices exhibit a staggering 20‐fold stability improvement in its performance half‐life compared with PEDOT/PSS devices, ~3400 h versus ~150 h, respectively. A further comparison of the stability between encapsulated and unencapsulated devices demonstrates the necessity for protection from atmospheric moisture and oxygen but again highlights the lucrative nature of sMoOx as a protective anode‐modifying layer compared with PEDOT/PSS even under ambient conditions. Copyright © 2014 John Wiley & Sons, Ltd.

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The effect of a concentration graded cathode for organic solar cells

Cited by 8 publications

References 22 publications

Morphology characterization in organic and hybrid solar cells

Morphology characterization in organic and hybrid solar cells

Thermally induced vertical phase separation and photovoltaic characteristics of polymer solar cells for P3HT/PCBM composites

Improved lifetimes of organic solar cells with solution‐processed molybdenum oxide anode‐modifying layers

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