Arylene linkers in a series of new tetraazabenzodifluoranthene diimide dimers enable tuning of the 3D molecular structure of nonfullerene electron acceptors, facilitating observation of dramatic ...variation of the power conversion efficiency from 2.6% to 6.4% as the twist angle between the monomeric building blocks in the dimer is varied.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
2.
7.7% Efficient All-Polymer Solar Cells Hwang, Ye-Jin; Courtright, Brett A. E.; Ferreira, Amy S. ...
Advanced materials (Weinheim),
August 19, 2015, Volume:
27, Issue:
31
Journal Article
Peer reviewed
By controlling the polymer/polymer blend self‐organization rate, all‐polymer solar cells composed of a high‐mobility, crystalline, naphthalene diimide‐selenophene copolymer acceptor and a ...benzodithiophene‐thieno3,4‐bthiophene copolymer donor are achieved with a record 7.7% power conversion efficiency and a record short‐circuit current density (18.8 mA cm−2).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Fullerene‐free and processing additive‐free 8.5% efficient polymer solar cells are achieved by using a new 3,4‐ethylenedioxythiophene‐linked arylene diimide dimer with a 76° twist angle. The devices ...combine high (78–83%) external quantum efficiency with high (0.91–0.95 V) photovoltages and thus have relatively low optical bandgap energy loss.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We report a comparative study of polyethylenimine (PEI) and ethoxylated-polyethylenimine (PEIE) cathode buffer layers in high performance inverted organic photovoltaic devices. The work function of ...the indium–tin oxide (ITO)/zinc oxide (ZnO) cathode was reduced substantially (Δφ = 0.73–1.09 eV) as the molecular weight of PEI was varied from 800 g mol–1 to 750 000 g mol–1 compared with the observed much smaller reduction when using a PEIE thin film (Δφ = 0.56 eV). The reference inverted polymer solar cells based on the small band gap polymer PBDTT-FTTE (ITO/ZnO/PBDTT-FTTE:PC70BM/MoO3/Ag), without a cathode buffer layer, had an average power conversion efficiency (PCE) of 6.06 ± 0.22%. Incorporation of a PEIE cathode buffer layer in the same PBDTT-FTTE:PC70BM blend devices gave an enhanced performance with a PCE of 7.37 ± 0.53%. In contrast, an even greater photovoltaic efficiency with a PCE of 8.22 ± 0.10% was obtained in similar PBDTT-FTTE:PC70BM blend solar cells containing a PEI cathode buffer layer. The temporal stability of the inverted polymer solar cells was found to increase with increasing molecular weight of the cathode buffer layer. The results show that PEI is superior to PEIE as a cathode buffer layer in high performance organic photovoltaic devices and that the highest molecular weight PEI interlayer provides the highest temporal stability.
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Knowledge of the critical factors that determine compatibility, blend morphology, and performance of bulk heterojunction (BHJ) solar cells composed of an electron-accepting polymer and an ...electron-donating polymer remains limited. To test the idea that bulk crystallinity is such a critical factor, we have designed a series of new semiconducting naphthalene diimide (NDI)-selenophene/perylene diimide (PDI)-selenophene random copolymers, xPDI (10PDI, 30PDI, 50PDI), whose crystallinity varies with composition, and investigated them as electron acceptors in BHJ solar cells. Pairing of the reference crystalline (crystalline domain size L c = 10.22 nm) NDI-selenophene copolymer (PNDIS-HD) with crystalline (L c = 9.15 nm) benzodithiophene-thieno3,4-bthiophene copolymer (PBDTTT-CT) donor yields incompatible blends, whose BHJ solar cells have a power conversion efficiency (PCE) of 1.4%. However, pairing of the new 30PDI with optimal crystallinity (L c = 5.11 nm) as acceptor with the same PBDTTT-CT donor yields compatible blends and all-polymer solar cells with enhanced performance (PCE = 6.3%, J sc = 18.6 mA/cm2, external quantum efficiency = 91%). These photovoltaic parameters observed in 30PDI:PBDTTT-CT devices are the best so far for all-polymer solar cells, while the short-circuit current (J sc) and external quantum efficiency are even higher than reported values for 70-fullerene:PBDTTT-CT solar cells. The morphology and bulk carrier mobilities of the polymer/polymer blends varied substantially with crystallinity of the acceptor polymer component and thus with the NDI/PDI copolymer composition. These results demonstrate that the crystallinity of a polymer component and thus compatibility, blend morphology, and efficiency of polymer/polymer blend solar cells can be controlled by molecular design.
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A series of eight new donor–acceptor conjugated copolymers based on thiazolo5,4-dthiazole (TT) were synthesized by Suzuki and Stille polycondensations, and their optical, electronic structure, ...field-effect charge transport, and photovoltaic properties were investigated. The number-average molecular weight was moderate to high (20–103 kDa) for four of the new copolymers and low (<10 kDa) for the rest. The optical band gap (1.7–2.2 eV) and the ionization potential (4.9–5.7 eV) of the copolymers could be tuned by varying the strength of the electron-donating comonomers. X-ray diffraction analysis of the neat TT polymer thin films showed that they exhibit a lamellar crystalline morphology with a (100) d-spacing of 1.449–1.881 nm. The polymers had field-effect hole mobilities of 2 × 10–3–3 × 10–2 cm2/(V s). Although fullerene (PC71BM)-based bulk heterojunction solar cells showed that most of the new polymers had low photovoltaic power conversion efficiency (<2.4%), the standout polymer PDEHTT had a high efficiency of 5.7%. X-ray diffraction analysis and TEM imaging of PDEHTT/PC71BM blend films showed a bicontinuous nanoscale morphology with a crystalline polymer nanofiber (15–20 nm width) network.
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Two n-type semiconducting polymers with alternating arylene (thiophene or selenophene)–tetraazabenzodifluoranthene diimide (BFI) donor–acceptor architecture have been investigated as new electron ...acceptors in polymer/polymer blend solar cells. The new selenophene-linked polymer, PBFI-S, has a significantly smaller optical band gap (1.13 eV) than the thiophene-linked PBFI-T (1.38 eV); however, both polymers have similar HOMO/LUMO energy levels determined from cyclic voltammetry. Blends of PBFI-T with the thiazolothiazole–dithienylsilole donor polymer (PSEHTT) gave a 2.60% power conversion efficiency (PCE) with a 7.34 mA/cm2 short-circuit current. In contrast, PBFI-S:PSEHTT blends had a 0.75% PCE with similarly reduced photocurrent and external quantum efficiency. Reduced free energy for charge transfer and reduced bulk electron mobility in PBFI-S:PSEHTT blends compared to PBFI-T:PSEHTT blends as well as significant differences in bulk film morphology are among the reasons for the large loss in efficiency in PBFI-S:PSEHTT blend solar cells.
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All-polymer solar cells composed of binary blends of donor poly4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo1,2-b;4,5-b′dithiophene-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno3,4-bthiophene-)-2–6-diyl) ...(PBDTTT-CT ), and acceptor polymers naphthalene diimide-selenophene copolymer (PNDIS-HD) and perylene diimide-selenophene copolymer (PPDIS) had power conversion efficiencies (PCEs) of 1.3 and 2.1%, respectively. Ternary blend solar cells composed of PBDTTT-CTPNDIS-HD1−xPPDISx at 75 wt% PPDIS had a PCE of 3.2%, which is about a 50%–140% enhancement compared with the binary blend devices. Equality of the ternary blend short-circuit current to the sum of those of the binary blend devices, among other results, provided evidence of a parallel-like bulk heterojunction mechanism in the ternary blend solar cells. These results provide the first example of enhanced performance in ternary blend all-polymer solar cells.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
9.
7.7% Efficient All-Polymer Solar Cells Hwang, Ye-Jin; Courtright, Brett A. E.; Ferreira, Amy S. ...
Advanced materials (Weinheim),
07/2015, Volume:
27, Issue:
31
Journal Article
Peer reviewed
By controlling the polymer/polymer blend self-organization rate, all-polymer solar cells composed of a high-mobility, crystalline, naphthalene diimide-selenophene copolymer acceptor and a ...benzodithiophene-thieno3,4-bthiophene copolymer donor are achieved with a record 7.7% power conversion efficiency and a record short-circuit current density (18.8 mA cm-2).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
10.
7.7% Efficient All-Polymer Solar Cells Hwang, Ye-Jin; Courtright, Brett A. E.; Ferreira, Amy S. ...
Advanced materials (Weinheim),
07/2015, Volume:
27, Issue:
31
Journal Article
Peer reviewed
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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