Vacuum deposited ternary mixture organic solar cells

Williams, Graeme; Aziz, Hany

doi:10.1016/j.orgel.2014.12.021

Cited by 9 publications

(9 citation statements)

References 59 publications

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“…This is in agreement with the experimentally observed correlation between optimal fill factor and optimal PCE. 6,7,17 Second, in Figure 8 the overall optimal PCE is still located on the binary line, where both donors have the same HOMO and LUMO. This reiterates the superiority of a single optimal bandgap provided the absorption is sufficiently broad.…”

Section: Selecting Optimal Donor Materials and Compositionsmentioning

confidence: 95%

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Open circuit voltage and efficiency in ternary organic photovoltaic blends

Felekidis

Wang

Kemerink

2016

Energy Environ. Sci.

104

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Organic bulk heterojunction solar cells based on ternary blends of two donor absorbers and one acceptor are investigated by experiments and modeling. The commonly observed continuous tunability of the open circuit voltage with donor1:donor2 ratio can quantitatively be explained as quasi-Fermi level splitting due to photocreated charges filling a joint density of states that is broadened by Gaussian disorder. On this basis, a predictive model for the power conversion efficiency that accounts for the composition-dependent absorption and the shape of the current-voltage characteristic is developed. When all other parameters, most notably the fill factor, are constant, we find that for state-of-the-art absorbers, having a broad and strong absorption spectrum, ternary blends offer no advantage over binary ones. For absorbers with a more narrow absorption spectrum ternary blends of donors with complementary absorption spectra, offer modest improvements over binary ones. In contrast, when, upon blending, transport and/or recombination kinetics are improved, leading to an increased fill factor, ternaries may offer significant advantages over binaries. Broader contextSolar cells based on blends of organic semiconductors almost routinely reach power conversion efficiencies (PCE) in the 10% range. One of the strategies that has been proposed to push this limit further upward is the use of so-called ternary blends in which two instead of one absorbing donor material is blended with the electron acceptor. Systematic improvement of PCE by ternary blending has been reported. Despite the experimental success, the current understanding of both the PCE enhancement and the underlying puzzling tunability of the open circuit voltage Voc is limited and essentially qualitative. In this contribution we develop and validate a quantitative and predictive framework for both the Voc and PCE of ternary organic solar cells, which allows us to propose design rules. In contrast to current wisdom, we demonstrate that PCE enhancement in ternary blends hardly results from optimizing the overlap with the solar spectrum but predominantly from synergetic improvement of the charge transport and recombination kinetics. The model can be easily extended to include more detail and will allow other researchers to upfront evaluate the photovoltaic potential of 'any' ternary material combination. 10 On the same basis Savoie et al. proposed an empirical expression for Voc as a current-weighted average of the two sub-systems and used this to estimate a maximal theoretical PCE (of 13%) for varying donor bandgaps. 11 Apart from lacking a formal basis, there are two problems with the parallel junction picture. First, it relies on a specific morphology in the active layer that allows different regions to act as independent binary cells that are electrically decoupled. Even if a fortunate morphology would lead to the presence of two (hole-) percolating networks that are electrically isolated from each other, the presence of metal contacts does unavoidably enforce...

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Section: Selecting Optimal Donor Materials and Compositionsmentioning

confidence: 95%

“…In practice, especially the fill factor can depend significantly on composition, as e.g. in References 6,7,17 , leading to optimal ternary compositions. Where this is not the case, e.g.…”

Section: Selecting Optimal Donor Materials and Compositionsmentioning

confidence: 99%

Open circuit voltage and efficiency in ternary organic photovoltaic blends

Felekidis

Wang

Kemerink

2016

Energy Environ. Sci.

104

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“…Some recent examples utilizing such approaches include chloro aluminum Pc (Cl-AlPc) and chloro gallium Pc (Cl-GaPc). These examples have been paired with C 60 for the fabrication of a bilayer and even blended organic solar cells. − Cl-AlPc and Cl-GaPc have also been used as interlayers between PEDOT:PSS and a blended solution of poly(3,3″-didodecylquaterthiophene) (PQT-12) and [6,6]-phenyl-C 61 -butyric acid methyl ester to form bilayer bulk heterojunction solar cells. , …”

Section: Introductionmentioning

confidence: 99%

Straightforward and Relatively Safe Process for the Fluoride Exchange of Trivalent and Tetravalent Group 13 and 14 Phthalocyanines

et al. 2019

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To avoid the use of hydrofluoric acid, a series of fluorinated trivalent and tetravalent metal-containing phthalocyanines (MPcs) were synthesized using a straightforward one-step halide substitution process using cesium fluoride (CsF) as the fluoride source and by reflux in N , N -dimethylformamide for less than an hour. The resulting fluoro MPcs were characterized and compared to the parent chloro MPcs. In some cases, very little change in properties was observed between the fluoro MPcs and the chloro MPcs. In other cases, such as fluoro aluminum phthalocyanine, a blue shift in the absorbance characteristics and an increase in oxidation and reduction potential of as much as 0.22 V was observed compared to the chloro derivative. Thermo gravimetric analysis was performed on all halo-MPcs, indicating that the choice of halo substitution on the axial position can have an effect on the decomposition or sublimation temperature of the final compound. After initial establishment and characterization of the fluoro MPcs, the halide substitution reaction of difluoro silicon phthalocyanine (F 2 -SiPc) was further explored by scaling the reaction up to a gram scale as well as considering tetrabutylammonium fluoride (TBAF) as an additional safe fluoride source. The scaled-up reactions producing F 2 -SiPc using CsF and TBAF as fluoride exchange sources were successfully reproducible, resulting in reaction yields of 100 and 73%, respectively. Both processes led to pure final products but results indicate that CsF, as the fluoride exchange reagent, appears to be the superior reaction process as it has a much higher yield.

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“…Vacuum-deposited ternary OPVs have only recently been reported using two donors, chloroindium phthalocyanine and boron subphthalocyanine chloride, codeposited with C 60 . 20 The absorption range is successfully extended to the near-infrared (NIR) region because of the complementary absorption of the two donors. However, the devices showed poor performance and a PCE of 2.08%, which is lower than that of binary systems.…”

Section: ■ Introductionmentioning

confidence: 99%

Efficient Vacuum-Deposited Ternary Organic Solar Cells with Broad Absorption, Energy Transfer, and Enhanced Hole Mobility

Moon

Kim

Wang

et al. 2016

ACS Appl. Mater. Interfaces

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The use of multiple donors in an active layer is an effective way to boost the efficiency of organic solar cells by broadening their absorption window. Here, we report an efficient vacuum-deposited ternary organic photovoltaic (OPV) using two donors, 2-((2-(5-(4-(diphenylamino)phenyl)thieno[3,2-b]thiophen-2-yl)thiazol-5-yl)methylene)malononitrile (DTTz) for visible absorption and 2-((7-(5-(dip-tolylamino)thiophen-2-yl)benzo[c]-[1,2,5]thiadiazol-4-yl)methylene)malononitrile (DTDCTB) for near-infrared absorption, codeposited with C70 in the ternary layer. The ternary device achieved a power conversion efficiency of 8.02%, which is 23% higher than that of binary OPVs. This enhancement is the result of incorporating two donors with complementary absorption covering wavelengths of 350 to 900 nm with higher hole mobility in the ternary layer than that of binary layers consisting of one donor and C70, combined with energy transfer from the donor with lower hole mobility (DTTz) to that with higher mobility (DTDCTB). This structure fulfills all the requirements for efficient ternary OPVs.

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Vacuum deposited ternary mixture organic solar cells

Cited by 9 publications

References 59 publications

Open circuit voltage and efficiency in ternary organic photovoltaic blends

Open circuit voltage and efficiency in ternary organic photovoltaic blends

Straightforward and Relatively Safe Process for the Fluoride Exchange of Trivalent and Tetravalent Group 13 and 14 Phthalocyanines

Efficient Vacuum-Deposited Ternary Organic Solar Cells with Broad Absorption, Energy Transfer, and Enhanced Hole Mobility

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