Polymer Solar Cells Based on a Low-Bandgap Fluorene Copolymer and a Fullerene Derivative with Photocurrent Extended to 850 nm

Zhang, Fengling; Perzon, Erik; Wang, Xiangjun; Mammo, Wendimagegn; Andersson, Mats R.; Inganäs, Olle

doi:10.1002/adfm.200400416

Cited by 236 publications

(153 citation statements)

References 22 publications

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“…For the electron donor materials, one most important property is a strong absorption covering a broad spectral region whereas the band gap is less than 2 eV. [13][14][15][16] Another important issue is minimizing the loss processes in the bulk during the exciton and charge transport. The photocurrent generation in the polymer solar cells generally involves in five steps as shown in Scheme 1: (1) absorption of light by the active layer, resulting in creation of excitons, (2) exciton transport to the donor (D)-acceptor (A) interface, (3) dissociation of excitons at the interface of electron donor/ acceptor interface, (4) transport of the charges, and (5) charge collection by electrodes.…”

Section: Introductionmentioning

confidence: 99%

A Density Functional Study of Furofuran Polymers as Potential Materials for Polymer Solar Cells

Xie¹,

Shen²,

He³

et al. 2013

Bulletin of the Korean Chemical Society

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The structural, electronic, and optical properties of poly(3-hexylthiophene) (P3HT) have been comprehensively studied by density functional theory (DFT) to rationalize the experimentally observed properties. Rather, we employed periodic boundary conditions (PBC) method to simulate the polymer block, and calculated effective charge mass from the band structure calculation for describing charge transport properties. The simulated results of P3HT are consistent with the experimental results in band gaps, absorption spectra, and effective charge mass. Based on the same calculated methods as P3HT, a series of polymers have been designed on the basis of the two types of building blocks, furofurans and furofurans substituted with cyano (CN) groups, to investigate suitable polymers toward polymer solar cell (PSC) materials. The calculated results reveal that the polymers substituted with CN groups have good structural stability, low-lying FMO energy levels, wide absorption spectra, and smaller effective masses, which are due to their good rigidity and conjugation in comparison with P3HT. Besides, the insertion of CN groups improves the performance of PSC. Synthetically, the designed polymers PFF1 and PFF2 are the champion candidates toward PSC relative to P3HT.

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Section: Introductionmentioning

confidence: 99%

A Density Functional Study of Furofuran Polymers as Potential Materials for Polymer Solar Cells

Xie¹,

Shen²,

He³

et al. 2013

Bulletin of the Korean Chemical Society

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“…Substantial photocurrents in the CyA and CyBs absorption ions necessitate cyanines with lower HOMO energy levels. e balanced design of the molecular frontier orbital levels is nerally a challenge when using low-bandgap materials, in er to maintain both the efficiency of charge generation and h open-circuit voltage at the same time [7,14]. If both elecn transfer reactions take place and assuming complete photon sorption, the absorption edge of almost 1000 nm for CyBs,l ults in potentially high photocurrents since more than 80% the incoming solar light is harvested [26].…”

Section: Resultsmentioning

confidence: 99%

“…This critical issue is being addressed increasingly [2,[8][9][10][11][12], and inventive device concepts try to combine the high efficiency of charge generation of the bulk with the low resistance to charge transport of the planar heterojunction in single device configurations [3,6], Another focus of attention in the research on organic solar cells is the development of materials that harvest more photons at long wavelengths. This is because most popular organic solar ls [13] are based on materials that absorb light primarily in ultraviolet and visible region, and a further increase in effincy requires novel low-bandgap compounds to increase the otocurrent [14]. In this connection, cyanine dyes have attracted attention as ive components for optoelectronic applications [15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

On the use of cyanine dyes as low-bandgap materials in bulk heterojunction photovoltaic devices

et al. 2006

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Cyanine dyes with absorption edges of almost 1000 nm were used in combination with MEH-PPV for the fabrication of organic solar cells. For blended thin films, a pronounced phase separation between the two components occurred and resulted in photocurrents with different signs for bilayer and bulk heterojunction devices. Absorption spectra and selective dissolution experiments were used to illustrate the process of vertical phase segregation, with the preferential wetting of the polar anode by the cyanines while maintaining percolating carrier pathways between the electrodes. For a cyanine with long alkyl side chains, the compatibility with the polymer matrix was increased and the development of the effective inverted bilayer configuration was not observed. The generally low oxidative photocurrents were explained with unfavourable shifts of the highest occupied molecular orbital (HOMO) dye energy levels in the solid state.

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“…5 Therefore, intensive efforts have been made to synthesize semiconducting materials that absorb at longer wavelengths and collect a larger fraction of the incident sunlight. [11][12][13][14] For this purpose, cyanine dyes are also of interest. 15 Cyanines are charged polymethine dyes that benefit from high extinction coefficients and a tunable absorption spectrum by varying the number of double bonds.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced hole-transfer in semiconducting polymer/low-bandgap cyanine dye blends: evidence for unit charge separation quantum yield

Castro

Benmansour

Moser

et al. 2009

Phys. Chem. Chem. Phys.

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Power-conversion efficiencies of organic heterojunction solar cells can be increased by using semiconducting donor-acceptor materials with complementary absorption spectra extending to the near-infrared region. Here, we used continuous wave fluorescence and absorption, as well as nanosecond transient absorption spectroscopy to study the initial charge transfer step for blends of a donor poly(p-phenylenevinylene) derivative and low-band gap cyanine dyes serving as electron acceptors. Electron transfer is the dominant relaxation process after photoexcitation of the donor. Hole transfer after cyanine photoexcitation occurs with an efficiency close to unity up to dye concentrations of B30 wt%. Cyanines present an efficient self-quenching mechanism of their fluorescence, and for higher dye loadings in the blend, or pure cyanine films, this process effectively reduces the hole transfer. Comparison between dye emission in an inert polystyrene matrix and the donor matrix allowed us to separate the influence of self-quenching and charge transfer mechanisms. Favorable photovoltaic bilayer performance, including high open-circuit voltages of B1 V confirmed the results from optical experiments. The characteristics of solar cells using different dyes also highlighted the need for balanced adjustment of the energy levels and their offsets at the heterojunction when using low-bandgap materials, and accentuated important effects of interface interactions and solid-state packing on charge generation and transport. IntroductionThe potential of cheap photovoltaics is fueling the interest in organic semiconductors. [1][2][3][4] State-of-the-art devices are made from a combination of electron-donor and electron-acceptor (D-A) materials, sandwiched between metallic electrodes. 5 Photoexcitation of either of the two components leads to an exciton that can dissociate into free charge carriers at the D-A interface. 6 After charge separation, electrons and holes are transported via drift and diffusion processes to the electrodes, where they are collected, giving rise to an electric current. 2 Device efficiency is determined by the short-circuit current (J sc ), the open-circuit voltage (V oc ), and the fill factor (FF) via Z = (J sc V oc FF)/P, where P is the incident optical power. The FF is a measure of the ability to transport and extract charges when the applied voltage approaches V oc ; J sc is determined by the fraction of absorbed photons from the incident sunlight as well as by the ability to create charges via exciton dissociation at the D-A interface. Consensus has now been reached that V oc correlates with the energy difference (E D ) between the highest occupied molecular orbital (HOMO) of the donor and the lowest unoccupied molecular orbital (LUMO) of the acceptor. [7][8][9] It follows that both J sc and V oc depend on the donor and acceptor energy levels and their offsets at the heterojunction (for illustration, see Fig. 1c). A high V oc requires a high E D . However, this implies that the HOMO-HOMO (E HH ) and LUMO-LUMO (E...

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Polymer Solar Cells Based on a Low-Bandgap Fluorene Copolymer and a Fullerene Derivative with Photocurrent Extended to 850 nm

Cited by 236 publications

References 22 publications

A Density Functional Study of Furofuran Polymers as Potential Materials for Polymer Solar Cells

A Density Functional Study of Furofuran Polymers as Potential Materials for Polymer Solar Cells

On the use of cyanine dyes as low-bandgap materials in bulk heterojunction photovoltaic devices

Photoinduced hole-transfer in semiconducting polymer/low-bandgap cyanine dye blends: evidence for unit charge separation quantum yield

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