Solar‐Energy Production and Energy‐Efficient Lighting: Photovoltaic Devices and White‐Light‐Emitting Diodes Using Poly(2,7‐fluorene), Poly(2,7‐carbazole), and Poly(2,7‐dibenzosilole) Derivatives

Beaupré, Serge; Boudreault, Pierre‐Luc; Leclerc, Mario

doi:10.1002/adma.200903484

Cited by 225 publications

(100 citation statements)

References 180 publications

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“…[6][7][8] The majority of the improvement, however, came from the development of low band gap polymers. 3,4,[9][10][11][12][13][14][15][16][17] By decreasing the bandgap of the donor, the amount of absorbed photon flux increases due to an enhanced overlap with the solar spectrum. A lowering of the polymer band gap can either be achieved by a lowering of the lowest unoccupied molecular orbital (LUMO) or by a raise of the highest occupied molecular orbital (HOMO).…”

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confidence: 99%

Role of balanced charge carrier transport in low band gap polymer:Fullerene bulk heterojunction solar cells

Kotlarski

Moet

Blom

2011

J Polym Sci B Polym Phys

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Lowering of the optical band gap of conjugated polymers in bulk heterojunction solar cells not only leads to an increased absorption but also to an increase of the optimal active layer thickness due to interference effects at longer wavelengths. The increased carrier densities due to the enhanced absorption and thicker active layers make low band gap solar cells more sensitive to formation of space charges and recombination. By systematically red shifting the optical parameters of poly[2-methoxy-5-(3 0 ,7and 6,6-phenyl C 61 -butyric acid methyl ester, we simulate the effect of a reduced band gap on the solar cell efficiencies. We show that especially the fill factor of low band gap cells is very sensitive to the balance of the charge transport. For a low band gap cell with an active layer thickness of 250 nm, the fill factor of 50% for balanced transport is reduced to less than 40% by an imbalance of only one order of magnitude. The efficiency of organic polymer:fullerene bulk heterojunction solar cell performance has been steadily increasing in the last years, going from 2.5% efficiency in 2001 1 to 3.5% in 2003, 2 up to 5.5% in 2007, 3,4 and recently an efficiency of 7.4% has been reported. 5 Part of the improvement originated from the refinement of existing production techniques to optimize the active layer morphology.6-8 The majority of the improvement, however, came from the development of low band gap polymers. 3,4,[9][10][11][12][13][14][15][16][17] By decreasing the bandgap of the donor, the amount of absorbed photon flux increases due to an enhanced overlap with the solar spectrum. A lowering of the polymer band gap can either be achieved by a lowering of the lowest unoccupied molecular orbital (LUMO) or by a raise of the highest occupied molecular orbital (HOMO). The lowering of the LUMO is limited by the energy offset needed for electron transfer to the acceptor, typically 0.4 eV. A raise of the HOMO on the other hand will lead to a decrease of the open circuit voltage V oc . A theoretical study by Koster et al. 18 showed that a decrease of the bandgap from 2.1 to 1.5 eV, by lowering the LUMO and keeping the HOMO in place, is expected to result in an increase in power conversion efficiency g from 3.5% to over 8%. This enhanced performance mainly originated from an increased short circuit current density J sc due to an increased absorption. However, an increased absorption because of a better spectral overlap with the solar sprectrum also leads to an increased concentration of electrons and holes in the solar cells. This enhancement of the carrier density then gives rise to an increase of the bimolecular recombination, which is proportional to the product of the electron and hole density. Furthermore, the higher carrier densities make the solar cells also more sensitive for the built-up of space charge, caused by an imbalanced charge transport. Space charge built-up is also dependent on the absorption profiles in the solar cell, which were not included in these calculations. To obtain more in...

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confidence: 99%

Role of balanced charge carrier transport in low band gap polymer:Fullerene bulk heterojunction solar cells

Kotlarski

Moet

Blom

2011

J Polym Sci B Polym Phys

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“…For the LEP, a single conjugated polymer system of PFO is used. 16 When doped with triplet emitters, the EL emission color can be changed from blue to green or red. 17,18 The LIFT deposited devices are referred to as a LIFTed pixels to differentiate them from conventionally fabricated devices.…”

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confidence: 99%

Red-green-blue polymer light-emitting diode pixels printed by optimized laser-induced forward transfer

Shaw-Stewart

Lippert

Nagel

et al. 2012

Applied Physics Letters

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An optimized laser-induced forward transfer (LIFT) technique has been used to fabricate tri-color organic light-emitting diode (OLED) pixels. At reduced pressures, and with a defined donor-receiver gap, patterned depositions of polyfluorene-based OLED pixels have been achieved. OLED pixel functionality has been demonstrated and compared with devices made using conventional deposition techniques. In addition, improved functionality has been obtained by coating the cathode with an electron-injecting layer, a process not possible using conventional OLED fabrication techniques. The OLED pixels fabricated by LIFT reach efficiencies on the range of conventionally fabricated devices and even surpass them in the case of blue pixels.

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“…N-6-(tetrahydro-2H-pyran-2-yloxy)hexyl-3, 4-dibromophenyl maleimide (3) Bis(4-bromophenyl)maleimide (2.80 g, 6.90 mmol) was treated with potassium tert-butoxide (1.54 g, 13.8 mmol) in dimethylformamide (20 ml) at 0 1C. After 2 h of stirring, 2-(6-bromohexyloxy)tetrahydro-2H-pyran (1.81 g, 13.8 mmol) was added to the solution, which was then stirred at room temperature for 10 h. After evaporating the volatiles under reduced pressure, the residue was dissolved in EtOAc and washed with water.…”

Section: Experimental Procedures Synthesis Of Maleimide-thiophene Copomentioning

confidence: 99%

“…[1][2][3][4][5][6] The photoactive layer in most bulk heterojunction cells is based on a blend of an electron-donor conjugated polymer and an electronacceptor fullerene derivative, typically [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM). Several recent efforts have focused on the synthesis of a new low-band gap conjugated polymers that improve the absorption of solar radiation and increase charge mobilities.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and photovoltaic properties of a series of bulk heterojunction solar cells based on interchain-linked conjugated polymers

Lee

Chen

Shiau

2012

Polym J

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We have used Suzuki coupling to synthesize a series of maleimide-thiophene copolymers presenting pendent 2-hydroxyethyl and 6-hydroxyhexyl units. The maleimide-thiophene copolymers containing different contents of OH groups were then reacted with 3,3 0 -dimethoxy-4,4 0 -biphenylene diisocyanate (DMBPI) in solution to form the interchain-linked polymers. The interchainlinked polymers exhibited excellent solubility in organic solvents. The average molecular weight and thermal stability of the copolymers increased after interchain linking with DMBPI. The wavelengths of maximum absorption of the interchain-linked copolymers were red-shifted relative to those of the corresponding side-chain copolymers. The energy level of the lowest unoccupied molecular orbitals and highest occupied molecular orbitals decreased after the copolymers had undergone interchain linking with DMBPI. We fabricated polymer solar cells (PSCs) from blends of the interchain-linked copolymers and Keywords: fullerene derivative; maleimide-thiophene copolymer; polymer solar cell INTRODUCTIONThe development of novel low-band gap p-conjugated polymers is an attractive research area because bulk heterojunction polymer solar cells (PSCs) incorporating them can be fabricated at low cost with large areas, flexible shapes, light weight and solution processability. [1][2][3][4][5][6] The photoactive layer in most bulk heterojunction cells is based on a blend of an electron-donor conjugated polymer and an electronacceptor fullerene derivative, typically [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM). Several recent efforts have focused on the synthesis of a new low-band gap conjugated polymers that improve the absorption of solar radiation and increase charge mobilities. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] In addition to the intrinsic characteristics of the polymer, the amount of PCBM in the blend, 17,18 the compatibility of the polymer and PCBM, the morphology of the photoactive layer 19-21 and the deviceprocessing conditions all have important roles affecting the photovoltaic (PV) performance of PSCs. [8][9][10]22,23 Photo-energy conversion efficiencies (Z) of 47% have been achieved for PSCs based on blends of poly(thiophene) derivatives and fullerene derivatives. [7][8][9][10]24,25 In addition to the short-circuit current densities (J SC ) and values of Z that are typically measured, recent investigations have also been made into optimizing the PV efficiency stability of PSCs. For example, incorporation of a ultraviolet (UV) shielding layer into a PSC can

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Solar‐Energy Production and Energy‐Efficient Lighting: Photovoltaic Devices and White‐Light‐Emitting Diodes Using Poly(2,7‐fluorene), Poly(2,7‐carbazole), and Poly(2,7‐dibenzosilole) Derivatives

Cited by 225 publications

References 180 publications

Role of balanced charge carrier transport in low band gap polymer:Fullerene bulk heterojunction solar cells

Role of balanced charge carrier transport in low band gap polymer:Fullerene bulk heterojunction solar cells

Red-green-blue polymer light-emitting diode pixels printed by optimized laser-induced forward transfer

Synthesis and photovoltaic properties of a series of bulk heterojunction solar cells based on interchain-linked conjugated polymers

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