Electron Donor and Acceptor Spatial Distribution in Structured Bulk Heterojunction Photovoltaic Devices Induced by Periodic Photopolymerization

Watanabe, Satoshi; Fukuchi, Yasumasa; Fukasawa, Masako; Sassa, Takafumi; Uchiyama, Masanobu; Yamashita, Takashi; Matsumoto, Mutsuyoshi; Aoyama, Tetsuya

doi:10.1021/la3005618

Cited by 10 publications

(14 citation statements)

References 44 publications

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“…25,35,36 On the other hand, l d can be expected to be larger in QQT(CN)4 photovoltaic devices because of a significant reduction of the local heating effects at lower excitation densities. The l d values measured in QQT(CN)4 as-prepared and annealed films suggest that the realization of an ideal photovoltaic device structure would require the realization of interdigitated p-n stripes 12,41 with a period of about 10 nm. The realization of p-n stripes with a period of few tenths of nm could be potentially achieved by techniques such as thermal nanoimprint lithography 42 or temperature-controlled dip pen nanolithography.…”

Section: Resultsmentioning

confidence: 99%

Exciton diffusion in near-infrared absorbing solution-processed organic thin films

Shin

Woo

Gwon

et al. 2013

Phys. Chem. Chem. Phys.

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We report on singlet-singlet annihilation and exciton diffusion in as-prepared p-type and annealed n-type thin films of the low-bandgap quinoidal quaterthiophene [QQT(CN)4] using ultrafast transient absorption measurements. The decay dynamics of exciton populations are well described by a one-dimensional diffusion-limited bimolecular recombination, indicating that the singlet excitons migrate preferentially along the stacking direction. Our results show that the exciton diffusion constants in QQT(CN)4 films do not vary significantly upon thermal annealing. Exciton diffusion lengths are measured to be as high as 4 and 5 nm in as-prepared and annealed QQT(CN)4 films, respectively. We also observe an influence of the excitation densities on the singlet exciton diffusion, which is attributed to phonon scattering. Because of the possibility of patterning p-n regions in QQT(CN)4 films by thermal nanolithography techniques, this study provides important insight not only into the photophysical properties of quinoidal oligothiophene derivatives but also for their future integration into high-performance p-n nanostructured near infrared light-sensing devices.

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Section: Resultsmentioning

confidence: 99%

Exciton diffusion in near-infrared absorbing solution-processed organic thin films

Shin

Woo

Gwon

et al. 2013

Phys. Chem. Chem. Phys.

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“…[1][2][3][4] Organic materials for solution based processes range from low melting point semiconductors, suitable for liquid electronics, to large polymers, soluble in various solvents. [5][6][7][8] Ongoing molecular engineering efforts aim at combining solution properties with optimized energy levels and charge transport properties to design high performance devices including transistors, 9,10 light emitting diodes or cavities, 11,12 memories, 4,6 and solar cells.…”

Section: Introductionmentioning

confidence: 99%

Enhanced organic solar cells efficiency through electronic and electro-optic effects resulting from charge transfers in polymer hole transport blends

et al. 2016

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 and ‡ These authors contributed equally to this work.We demonstrate that blending fluorinated molecules in PEDOT:PSS hole transport layers (HTL) induces charge transfers which impact on both charge extraction and photogeneration within organic photovoltaic (OPV) devices. OPVs fabricated with modified HTL and two photoactive polymer blends led systematically to power conversion efficiencies (PCE) increases, with PTB7:PC70BM blend exhibiting PCE of ~ 8.3 %, i.e. ~ 15 % increase compared to pristine HTL devices. A reduced device-to-device characteristics variations was also noticed when fluorinated additives were used to modify the PEDOT:PSS. Shading lights onto the effect of HTL fluorination, we show that the morphology of the polymer:PCBM blends remains surprisingly unaffected by the fluorinated HTL surface energy but that, instead, the OPVs are impacted not only by the HTL electronic properties (work function, dipole layer, open circuit voltage, charge transfer dynamic) but also by alteration of the complex refractive indices (photogeneration, short circuit current density, external quantum efficiencies, electro-optic modelling). Both mechanisms find their origin in fluorination induced charge transfers. This work points towards fluorination as a promising strategy toward combining both external quantum efficiency modulation and power conversion efficiency enhancement in OPVs. Charge transfers could also be used more broadly to tune the optical constants and electric field distribution, as well as to reduce interfacial charge recombinations within OPVs. [21][22][23][24][25][26][27][28][29]

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“…[ 1 , 2 ] This novel group of nanomaterials exhibit a wide range of exotic and appealing properties, which render them interesting study objects for fundamental investigations [3][4][5][6][7][8][9] as well as exploitable as active materials in a plethora of ubiquitous applications, notably photovoltaic devices, [10][11][12][13][14][15][16][17] transistor arrays, [18][19][20] and integrated circuits. [ 1 , 2 ] This novel group of nanomaterials exhibit a wide range of exotic and appealing properties, which render them interesting study objects for fundamental investigations [3][4][5][6][7][8][9] as well as exploitable as active materials in a plethora of ubiquitous applications, notably photovoltaic devices, [10][11][12][13][14][15][16][17] transistor arrays, [18][19][20] and integrated circuits.…”

Section: Introductionmentioning

confidence: 99%

Photochemical Transformation of Fullerenes

Wang

Enevold

Edman

2013

Adv Funct Materials

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Experimental fi ndings and associated theoretical insights regarding the photochemical transformation of fullerenes are reported, which challenge the conventional wisdom in the fi eld and point out a viable path towards improved fullerene-based electronic devices. It is shown that the effi ciency of the photochemical monomer-to-dimer transformation of the fullerene [6,6 ′ ]-phenyl-C 61 -butyric acid methyl ester (PCBM) is strongly dependent on the light intensity, and this is utilized to demonstrate that direct patterning of an electroactive PCBM fi lm can be effectuated by sub-second UV-light exposure followed by development in a tuned developer solution. By straightforward analytical reasoning, it is demonstrated that the observed intensitydependent monomer-to-dimer transformation dictates that a signifi cant back-reaction to the ground state must be in effect, which presumably originates from the excited-triplet state. By a combination of numerical modeling and analytical argumentation, it is further shown that the fi nal dimer formation must constitute a bi-excited reaction between two neighboring monomers photo-excited to the triplet state.

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Electron Donor and Acceptor Spatial Distribution in Structured Bulk Heterojunction Photovoltaic Devices Induced by Periodic Photopolymerization

Cited by 10 publications

References 44 publications

Exciton diffusion in near-infrared absorbing solution-processed organic thin films

Exciton diffusion in near-infrared absorbing solution-processed organic thin films

Enhanced organic solar cells efficiency through electronic and electro-optic effects resulting from charge transfers in polymer hole transport blends

Photochemical Transformation of Fullerenes

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