H-aggregated small molecular nanowires as near infrared absorbers for organic solar cells

Holzmüller, Felix; Gräßler, Nico; Sedighi, Mona; Muller, Eric A.; Knupfer, M.; Zeika, Olaf; Vandewal, Koen; Koerner, Christian; Leo, Karl

doi:10.1016/j.orgel.2017.03.009

Cited by 12 publications

(13 citation statements)

References 33 publications

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“…In contrast, a bathochromic shift is attributed to J-aggregation with large lateral offsets along molecular transition dipoles in the solid state. Thus, both photophysical and electronic properties, which are critical factors for organic electronic devices, can be modified by tuning the aggregation type. − Insights into the influence of the donor’s aggregation on OSC parameters have been reported for certain molecules, such as squaraines, oligothiophenes, and diketopyrrolopyrroles. − However, little information exists for the effect on V oc , which is curretnly the limiting parameter of the PCE in OSCs. − Quantitively, the voltage loss (Δ E loss / q ) from the optical band gap ( E opt ) to qV oc is given by where Δ E CT is the driving force for the formation of a charge-transfer (CT) state from the initially excited singlet state localized on the donor molecule. Δ E rec / q is the voltage loss due to recombination of photoinduced charge carriers, which can be further divided into inevitable radiative recombination losses (Δ V r ) and nonradiative recombination voltage losses (Δ V nr ) .…”

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confidence: 99%

Effect of H- and J-Aggregation on the Photophysical and Voltage Loss of Boron Dipyrromethene Small Molecules in Vacuum-Deposited Organic Solar Cells

Benduhn

Qiao

et al. 2019

J. Phys. Chem. Lett.

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An understanding of the factors limiting the open-circuit voltage (V oc) and related photon energy loss mechanisms is critical to increase the power conversion efficiency (PCE) of small-molecule organic solar cells (OSCs), especially those with near-infrared (NIR) absorbers. In this work, two NIR boron dipyrromethene (BODIPY) molecules are characterized for application in planar (PHJ) and bulk (BHJ) heterojunction OSCs. When two H atoms are substituted by F atoms on the peripheral phenyl rings of the molecules, the molecular aggregation type in the thin film changes from the H-type to J-type. For PHJ devices, the nonradiative voltage loss of 0.35 V in the J-aggregated BODIPY is lower than that of 0.49 V in the H-aggregated device. In BHJ devices with a nonradiative voltage loss of 0.35 V, a PCE of 5.5% is achieved with an external quantum efficiency (EQE) maximum of 68% at 700 nm.

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confidence: 99%

Effect of H- and J-Aggregation on the Photophysical and Voltage Loss of Boron Dipyrromethene Small Molecules in Vacuum-Deposited Organic Solar Cells

Benduhn

Qiao

et al. 2019

J. Phys. Chem. Lett.

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“…Consequently, BDP-H and BDP-OMe have more J-aggregation character whereas BDP-Me has more H-type character . It is known that aggregation in thin films broadens the absorption spectra and a J-/H-aggregation can result in bathochromic/hypsochromic shifts . Moreover, charge transport in OSCs benefits from aggregation, leading to higher overall PCE through improved j sc and FF , even though V oc may decrease slightly …”

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Small Molecule Near-Infrared Boron Dipyrromethene Donors for Organic Tandem Solar Cells

Meyer

et al. 2017

J. Am. Chem. Soc.

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Three furan fused boron dipyrromethenes (BODIPYs) with a CF group on the meso-carbon are synthesized as near-infrared absorbing materials for vacuum processable organic solar cells. The best single junction device reaches a short-circuit current (j) of 13.3 mA cm and a power conversion efficiency (PCE) of 6.1%. These values are highly promising for an electron donor material with an absorption onset beyond 900 nm. In a tandem solar cell comprising a NIR BODIPY subcell and a matching "green" absorber subcell, complementary absorption is achieved, resulting in PCE of ∼10%.

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“…The unique spectral properties of J and H aggregates are attracting increasing attention as regards practical implementation for solar energy . Here we have pointed out another possible important application of a JH aggregate as the prime absorbing medium of a luminescent solar concentrator.…”

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confidence: 93%

Dye Aggregates in Luminescent Solar Concentrators

Eisfeld

Briggs

2017

Physica Status Solidi (a)

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In this paper the design of a luminescent solar concentrator (LSC) in which dye aggregates with cylindrical geometry are embedded in the LSC plate with the long cylinder axis orthogonal to the faces of the plate is proposed. The most suitable aggregates are those exhibiting a blue‐shifted (with respect to monomer absorption) H band and a narrow red‐shifted J band. Such aggregates have high primary absorption into the H band which is polarized in the plane of the LSC and emission from the J band which is polarized perpendicular to the plane. Hence the emitted light is directed predominantly to the edges of the LSC and loss into the escape zone is much reduced.

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H-aggregated small molecular nanowires as near infrared absorbers for organic solar cells

Cited by 12 publications

References 33 publications

Effect of H- and J-Aggregation on the Photophysical and Voltage Loss of Boron Dipyrromethene Small Molecules in Vacuum-Deposited Organic Solar Cells

Effect of H- and J-Aggregation on the Photophysical and Voltage Loss of Boron Dipyrromethene Small Molecules in Vacuum-Deposited Organic Solar Cells

Small Molecule Near-Infrared Boron Dipyrromethene Donors for Organic Tandem Solar Cells

Dye Aggregates in Luminescent Solar Concentrators

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