Conjugated Polymers for Organic Solar Cells

Ye, Qun

doi:10.5772/23275

Cited by 9 publications

(10 citation statements)

References 70 publications

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“…For example, a polymer with a band gap of ~2.0 eV can only absorb 25% of the solar energy. Reduction of the band gap to ~1.2 eV enhances absorption to between 70% and 80% as shown in Figure . For maximum absorption, a smaller band gap is favourable.…”

Section: Introductionmentioning

confidence: 95%

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A review on carbon nanotube/polymer composites for organic solar cells

Keru

Ndungu

Nyamori

2014

Int. J. Energy Res.

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SUMMARY Carbon nanotubes (CNTs) have unique properties, such as their electrical conductivity, that enable them to be combined with conducting polymers to form composites for use in organic solar cells (OSCs). It is envisaged that the improved composite has a higher efficiency of green energy and will reduce the cost of these cells. The use of such alternative energy sources also drastically reduces overuse of fossil fuels and consequently limits environmental degradation. This review compares research and performance between conventional silicon solar cells and OSCs. It also discusses OSC photoexcitation and charge carrier generation with the incorporation of CNTs, physicochemical properties of the composites and other factors that affect the efficiencies of OSCs. In addition, properties of CNTs that favour their dispersion in polymer matrices as acceptors and charge carriers to the electrodes are covered. The effects of CNTs containing dopants, such as nitrogen and boron, on charge transfer are discussed. Also, the fabrication techniques of OSCs that include CNT/polymer composite processing and the methods of film deposition on the substrate are described. Finally, the case studies of OSCs containing polymers with single‐walled CNTs, double‐walled CNTs or multi‐walled CNTs are evaluated. Copyright © 2014 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 95%

“…The blue line shows the absorption of a polymer with a band gap of ~2 eV and the red of ~1.2 eV. The black line represent AM 1.5 illumination .…”

Section: Introductionmentioning

confidence: 99%

A review on carbon nanotube/polymer composites for organic solar cells

Keru

Ndungu

Nyamori

2014

Int. J. Energy Res.

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“…However, the large band gaps of these polymers limit the absorption of photons from the sun. 11,12 In order to broaden the absorption spectrum, conjugated polymers with alternating electron-rich (donor) segments and electron-deficient (acceptor) segments were developed. 13,14 In the so where, F is the Coulomb force, q is the elementary charge, ε 0 is the vacuum dielectric constant, ε r is the relative dielectric constant of the material and r is the distance between the electron and the hole.…”

Section: Conjugated Polymersmentioning

confidence: 99%

Studies of Morphology and Charge-Transfer in Bulk-Heterojunction Polymer Solar Cells

Ma¹

2013

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The work presented in this thesis focuses on the two critical issues of bulk-heterojunction polymer solar cells: morphology of active layers and energy loss during charge transfer processes at electron donor/acceptor interfaces. Both issues determine the performance of polymer solar cells through governing exciton dissociation, charge carrier recombination and free charge carrier transport.The morphology of active layers (spatial percolation of the donor and acceptor) is crucial for the performance of polymer solar cells due to the limited diffusion length of excitons in organic semiconductors (5-20 nm). Meanwhile, the trade-off between charge generation and transport also needs to be considered. On the one hand, a finely mixed morphology with a large donor/acceptor interface area is preferred for charge generation because efficient exciton dissociation only occurs at the interface, but on the other hand, proper phase separation is needed to reduce charge carrier recombination and facilitate free charge carrier transport to the electrodes. In this thesis, morphologies of the active layers based on different polymeric donors and fullerene acceptors are correlated to the performance of solar cells with various microscopic and spectroscopic techniques including atomic force microscope, transmission electron microscope, grazing incidence x-ray diffraction, photoluminescence, electroluminescence and Fourier transform photocurrent spectroscopy. Furthermore, methods to manipulate the morphologies of solution processed active layers to achieve high performance solar cells are also presented. Processing solvents, chemical structures of the donor and the acceptor materials, and substrate surface properties are found critically important in determining the nanoscale phase separation and performance of polymer solar cells.Optimizing morphology of active layers alone does not guarantee high performance devices. In addition to spatial percolation, energy arrangements of donors and acceptors are also essential due to contrary requests of the photocurrent and the photovoltage: Efficient exciton dissociation or charge transfer at donor/acceptor interfaces requires large enough energetic driving force, which is also known as energy loss for charge transfer. However, the energy loss due to charge transfer will unavoidably reduce the photovoltage. In this thesis the balance between the photocurrent and the photovoltage in polymer solar cells due to charge transfer at donor/acceptor interfaces is investigated for different active material systems. The driving force tuned by synthesizing series of polymers is determined by directly measuring the optical band gap via UV-Vis spectroscopy and probing the charge transfer recombination via electroluminescence measurements. Influences of driving force on the photocurrent and the photovoltage are characterized via field dependent photoluminescence and internal quantum efficiency measurements. The results correlated well with the performance of the solar cells. VI Populärvetenskaplig...

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“…Solar energy has proven to be a promising alternate energy source to the finite, environmentally harmful fossil fuels that are currently used as the world's main source of energy [1]. Inorganic solar cells, based on crystalline silicon, have demonstrated efficiencies in excess of 25 % [2].…”

Section: Introductionmentioning

confidence: 99%

Preparation and photovoltaic properties of pyrene-thieno[3,4-c]pyrrole-4,6-dione-based donor-acceptor polymers

Alqurashy

Iraqi

Zhang

et al. 2016

European Polymer Journal

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Four new donor-acceptor conjugated copolymers, containing pyrene moieties flanked by thienyl or bithienyl groups as a donor units and thieno[3,4-c]pyrrole-4,6-dione (TPD) as acceptor units, were successfully prepared via a direct arylation polymerisation method. While all polymers prepared had 2-ethylhexyloxy-substituents on the pyrene repeat units, two different alkylsusbtituents (octyl or 4-hexylphenyl groups) were attached to their TPD moieties. The influence of these different substituents as well as the number of thienyl units linking the pyrene and TPD units along polymer chains on the photophysical, electronic and photovoltaic properties of these materials was investigated. All polymers displayed good thermal stability up to 315°C. The optical band gap of the four polymers, PP EH DT-TPD O , PP EH DT-TPD HP , PP EH DT2-TPD O and PP EH DT2-TPD HP , were estimated to be 2.00, 2.06, 1.94 and 1.91 eV, respectively. Polymers that possessed a single thiophene unit attached to the pyrene unit, PP EH DT-TPD O and PP EH DT-TPD HP , displayed deeper HOMO levels compared to those with bithiophene units, PP EH DT2-TPD O a n d P P EH DT2-TPD HP. Photovoltaic devices were fabricated from all polymers. PP EH DT2-TPD O boasted the highest efficiency with a PCE (2.06 %), a FF of 53.07 %, a J sc of 4.66 mA/cm 2 and a V oc of 0.83 V.

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Conjugated Polymers for Organic Solar Cells

Cited by 9 publications

References 70 publications

A review on carbon nanotube/polymer composites for organic solar cells

A review on carbon nanotube/polymer composites for organic solar cells

Studies of Morphology and Charge-Transfer in Bulk-Heterojunction Polymer Solar Cells

Preparation and photovoltaic properties of pyrene-thieno[3,4-c]pyrrole-4,6-dione-based donor-acceptor polymers

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