Dual Function Additives: A Small Molecule Crosslinker for Enhanced Efficiency and Stability in Organic Solar Cells

Rumer, Joseph W.; Ashraf, Raja Shahid; Eisenmenger, Nancy D.; Huang, Zhenggang; Meager, Iain; Nielsen, Christian B.; Schroeder, Bob C.; Chabinyc, Michael L.; McCulloch, Iain

doi:10.1002/aenm.201401426

Cited by 63 publications

(60 citation statements)

References 27 publications

(29 reference statements)

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“…[3][4][5] In the active layer i.e. 9 Alternatively, groups have also used the technique of in situ cross-linking with the introduction of small UV-curable bis-amide crosslinker 18 as well as PCBM based thermo-cross-linkers as an additive to the BHJ layer. In blends, poly(3-hexylthiophene) (P3HT) and PCBM fullerene phase segregate and tend to initially form 6 nano-scale aggregates which increase in size during post-processing thermal annealing and are associated with improving device mobility and performance.…”

Section: Introductionmentioning

confidence: 99%

Thermo-cross-linkable fullerene for long-term stability of photovoltaic devices

et al. 2015

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In this study, a highly soluble PCBM-based thermo-cross-linkable fullerene precursor has been synthesized for use in bulk heterojunction based organic solar cells. The cross-linking was achieved using a thermally activated benzocyclobutene (BCB) molecule. The thermo-crosslinking reaction is initiated at temperatures as low as 150 C. Compared to PCBM, the cross-linked fullerene is highly insoluble and has a diffusional mobility in poly(3-hexylthiophene) (P3HT) that is an order of magnitude slower than PCBM. Its electron mobility is comparable to that of PCBM and organic photovoltaic (OPV) devices consisting of bulk heterojunction active layers with P3HT or PTB7 and this fullerene show very similar efficiencies. Devices prepared either with pure cross-linked fullerene or its mixture with PCBM as acceptors in OPVs have been shown to be highly stable to accelerated aging with little loss in device efficiency up to 48 hours of aging at 150 C. This compares to a loss of 60% of initial efficiency in identically prepared devices when using PCBM as the acceptor. Optical microscopy and grazing incidence wide angle X-ray scattering (GIWAXS) shows that a probable cause for this excellent stability in the cross-linked fullerene containing BHJs is associated with a significant inhibition of formation of crystals of fullerene.

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Section: Introductionmentioning

confidence: 99%

Thermo-cross-linkable fullerene for long-term stability of photovoltaic devices

et al. 2015

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“…13 Such third components can be crosslinkers, [14][15][16] In this work, we overcome the aggregation of the fullerene acceptor PC 61 BM during thermal annealing by employing ternary D-D-A blends comprising two commercially available donor polymers. After thermal stress at 120°C for 2 h, the corresponding solar cells maintain over 90% of their initial performance.…”

Section: Introductionmentioning

confidence: 99%

“…12 Another promising concept to reduce degradation in fullerene-based solar cells is the use of third components which can improve the mechanical, photo, air and thermal stability of organic solar cells. 13 Such third components can be crosslinkers, [14][15][16] conventional fullerenes, [17][18][19] modified fullerene derivatives, [20][21][22] compatibilizers 23,24 or insulating polymers. 25 In this work, we overcome the aggregation of the fullerene acceptor PC 61 BM during thermal annealing by employing ternary D-D-A blends comprising two commercially available donor polymers.…”

Section: Introductionmentioning

confidence: 99%

“…6,7 Upon thermal stress, one of the major degradation mechanisms is the aggregation of fullerene acceptors, commonly [6,6]-phenyl C 71 -butyric acid methyl ester (PC 71 BM) or [6,6]-phenyl C 61 -butyric acid methyl ester (PC 61 BM). 8,9 In the recent literature, several methods were discussed to hamper fullerene aggregation-for example sample irradiation during annealing, 10 structural modification of fullerenes 11 or replacing fullerenes with non-fullerene acceptors.12 Another promising concept to reduce degradation in fullerene-based solar cells is the use of third components which can improve the mechanical, photo, air and thermal stability of organic solar cells.13 Such third components can be crosslinkers, [14][15][16] In this work, we overcome the aggregation of the fullerene acceptor PC 61 BM during thermal annealing by employing ternary D-D-A blends comprising two commercially available donor polymers. After thermal stress at 120°C for 2 h, the corresponding solar cells maintain over 90% of their initial performance.…”

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confidence: 99%

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Enhanced thermal stability of organic solar cells comprising ternary D-D-A bulk-heterojunctions

et al. 2017

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Ternary absorber blends have recently been identified as promising concepts to spectrally broaden the absorption of organic bulkheterojunction solar cells and hence to improve their power conversion efficiencies. In this work, we demonstrate that D-D-A ternary blends comprising two donor polymers and the acceptor PC 61 BM can also significantly enhance the thermal stability of the solar cell. Upon harsh thermal stress at 120°C for 2 h, the ternary solar cells show only a minor relative deterioration of 10%. Whereas the polymer/fullerene blend PTB7-Th:PC 61 BM is rather unstable under these conditions, its degradation was efficiently suppressed by incorporating the near infrared-absorbing polymer PDTP-DFBT. Spectroscopic ellipsometry investigations and an effective medium analysis of the ternary absorber blend revealed that the domain conformation in presence of PDTP-DFBT remains stable whereas the domain conformation changes in its absence. The ternary PTB7-Th:PDTP-DFBT:PC 61 BM solar cells yield thermally stable power conversion efficiencies of up to 6%.npj Flexible Electronics (2017) 1:11 ; doi:10.1038/s41528-017-0011-z INTRODUCTIONThe continuous improvement of materials and device architectures for organic bulk-heterojunction solar cells nowadays constantly enables power conversion efficiencies (PCEs) beyond 10%.1, 2 While the PCEs of state-of-the-art organic solar cells are sufficient to meet the demands of some first applications and hence to foster market entry, the device stability often drags behind. The stability of organic solar cells is often limited by a metastable bulk-heterojunction morphology, the diffusion of electrode or buffer layer components into adjacent layers, material decomposition through oxygen and water ingress, irradiation, mechanical stress or heat.3-5 Yet, excellent thermal stability of the organic solar cells is a prerequisite for most future applications. Besides thermal stress when the solar cell is exposed to the sun, the devices may have to endure harsh conditions during fabrication, e.g., when manufacturing car roofs, tiles or façade elements, typically requiring lamination temperatures of 120°C for several hours. 6,7 Upon thermal stress, one of the major degradation mechanisms is the aggregation of fullerene acceptors, commonly [6,6]-phenyl C 71 -butyric acid methyl ester (PC 71 BM) or [6,6]-phenyl C 61 -butyric acid methyl ester (PC 61 BM). 8,9 In the recent literature, several methods were discussed to hamper fullerene aggregation-for example sample irradiation during annealing, 10 structural modification of fullerenes 11 or replacing fullerenes with non-fullerene acceptors.12 Another promising concept to reduce degradation in fullerene-based solar cells is the use of third components which can improve the mechanical, photo, air and thermal stability of organic solar cells.13 Such third components can be crosslinkers, [14][15][16] In this work, we overcome the aggregation of the fullerene acceptor PC 61 BM during thermal annealing by employing ternary D-D-A blends comprisi...

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“…In the group of McCulloch, SiIDT-BT was crosslinked using the bisazide DAZH (Figure 2), which improves the efficiency from 6.0% to 7.0%. [31] Thermal aging for 130 h at 85 °C resulted in an efficiency of 4.1% for the crosslinked cell compared to 3.5% for the reference cell.…”

Section: Overview Of the Chemistry Of Crosslinkable Materialsmentioning

confidence: 99%

Crosslinked Semiconductor Polymers for Photovoltaic Applications

Kahle

Saller

Köhler

et al. 2017

Advanced Energy Materials

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Organic solar cells (OSCs) have achieved much attention and meanwhile reach efficiencies above 10%. One problem yet to be solved is the lack of long term stability. Crosslinking is presented as a tool to increase the stability of OSCs. A number of materials used for the crosslinking of bulk heterojunction cells are presented. These include the crosslinking of low bandgap polymers used as donors in bulk heterojunction cells, as well as the crosslinking of fullerene acceptors and crosslinking between donor and acceptor. External crosslinkers often based on multifunctional azides are also discussed. In the second part, some work either leading to OSCs with high efficiencies or giving insight into the chemistry and physics of crosslinking are highlighted. The diffusion of low molar mass fullerenes in a crosslinked matrix of a conjugated polymer and the influence of crosslinking on the carrier mobility is discussed. Finally, the use of crosslinking to make stable interlayers and the solution processing of multilayer OSCs are discussed in addition to presentation of a novel approach to stabilize nanoimprinted patterns for OSCs by crosslinking.

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Dual Function Additives: A Small Molecule Crosslinker for Enhanced Efficiency and Stability in Organic Solar Cells

Cited by 63 publications

References 27 publications

Thermo-cross-linkable fullerene for long-term stability of photovoltaic devices

Thermo-cross-linkable fullerene for long-term stability of photovoltaic devices

Enhanced thermal stability of organic solar cells comprising ternary D-D-A bulk-heterojunctions

Crosslinked Semiconductor Polymers for Photovoltaic Applications

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