Boosting the photovoltaic thermal stability of fullerene bulk heterojunction solar cells through charge transfer interactions

Ho, Carr Hoi Yi; Cao, Huanyang; Lu, Yong; Lau, Tsz Ki; Cheung, Sin Hang; Li, Ho Wa; Yin, Hang; Chiu, Ka Lok; Kuen, Lik; Cheng, Yuanhang; Tsang, Sai‐Wing; Lu, Xinhui; So, Shu Kong; Ong, Beng S.

doi:10.1039/c7ta06530b

Cited by 15 publications

(7 citation statements)

References 41 publications

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“…It is envisioned that the solid‐state photoactive molecular mediator N(BAI) 3 may yield more stable device performance compared to the commonly used liquid‐state processing additives due to the absence of slow evaporation or migration of solvent additive residues in the bulk heterojunction films. In addition, it has been shown that multi‐armed molecules can facilitate the formation of a locked 3D mesh of donor polymer matrix through strong charge transfer interactions, resulting in enhanced thermal stability of devices by impeding the diffusion and aggregation of embedded PC 60 BM molecules . More comprehensive studies toward nanophase stability of the active layer and device stability are ongoing in our lab.…”

Section: Resultsmentioning

confidence: 94%

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Enhancing the Efficiency of Organic Photovoltaics by a Photoactive Molecular Mediator

et al. 2017

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High boiling‐point solvent additives, such as 1,8‐diiodooctane, have been widely used to tune nanoscale phase morphology for increased efficiency in bulk heterojunction organic solar cells. However, liquid‐state solvent additives remain in the active films for extended times and later migrate or evaporate from the films, leading to unstable device performance. Here, a solid‐state photoactive molecular mediator, namely N(BAI)3, is reported that could be employed to replace the commonly used solvent additives to tune the morphology of bulk heterojunction films for improved device performance. The N(BAI)3 mediator not only resides in the active films locally to fine tune the phase morphology, but also contributes to the additional absorption of the active films, leading to ∼11% enhancement of power conversion efficiency of P3HT:PC60BM devices. Comparative studies are carried out to probe the nanoscale morphologies using grazing incidence wide‐angle X‐ray scattering and complementary neutron reflectometry. The use of 1 wt% N(BAI)3 is found to effectively tune the packing of P3HT, presumably through balanced π‐interactions endowed by its large conjugated π surface, and to promote the formation of a PC60BM‐rich top interfacial layer. These findings open up a new way to effectively tailor the phase morphology by photoactive molecular mediators in organic photovoltaics.

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Section: Resultsmentioning

confidence: 94%

“…The volume fraction profiles were deduced from the data fits of the neutron reflectivity profiles shown in (a) as established in Ref. .…”

Section: Resultsmentioning

confidence: 99%

Enhancing the Efficiency of Organic Photovoltaics by a Photoactive Molecular Mediator

et al. 2017

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“…In addition, we measured the charge carrier mobility of optimized devices using the space-charge-limited current method. The device structures for hole and electron-only devices are glass/ITO/PEDOT/PSS/active layer/MoO 3 /Au and glass/Al/active layer/Al, respectively. , As shown in Figure a, the hole mobilities (μ h ) of TPDI-2P- and F-TPDI-2P-based blend films are 4.82 × 10 –5 and 8.76 × 10 –5 cm 2 V –1 s –1 , respectively, and the electron mobilities (μ e ) Figure b of TPDI-2P- and F-TPDI-2P-based blend films are 3.98 × 10 –5 and 6.82 × 10 –5 cm 2 V –1 s –1 , respectively, calculated from the slopes of J 1/2 – V curves. The higher μ h and μ e of the device based on F-TPDI-2P contribute to the improved J SC and FF values.…”

Section: Resultsmentioning

confidence: 99%

Thiophene–Perylenediimide Bridged Dimeric Porphyrin Donors Based on the Donor–Acceptor–Donor Structure for Organic Photovoltaics

Piradi

Gao

Yan

et al. 2022

ACS Appl. Energy Mater.

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Two D–A–D (D = donor, A = acceptor)-based small-molecule donors, TPDI-2P and F-TPDI-2P, are designed and synthesized for organic solar cells (OSCs), with two strong donor porphyrin units bridged by either an electron-deficient diethynyl-substituted thiophene–perylenediimide (TPDI) linker for the former or a diethynyl-fused TPDI linker for the latter; 3-ethylrhodanine units were then flanked symmetrically by phenylenethynylene π-linkers. Both compounds show strong absorption profiles from 400 to 800 nm, with a valley at 600 nm, attributed to the Soret and Q-bands of porphyrin units. Compared to TPDI-2P, F-TPDI-2P with a fused TPDI backbone exhibits high redshifted absorptions and low-lying energy levels due to increased coplanarity of the dimeric porphyrin units. As a result, the optimized photovoltaic device based on F-TPDI-2P/PC71BM has a decent power conversion efficiency (PCE) of 8.21%, whereas the device TPDI-2P/PC71BM has a slightly lower PCE (6.90%). The higher efficiency of F-TPDI-2P/PC71BM is mainly due to better photocurrent generation and smoother surface morphology with elevated charge carrier mobilities. The success of this molecular design strategy could be beneficial in the development of more efficient porphyrin-based donors for high-performance OSCs.

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“…The enhanced interchain interaction is sensitive to the improved CT state at the donor/acceptor interface and the charge carriers’ transport progress. Previously, Spano et al reported that the interchain coupling and the degree of structural order can be reflected in the absorption ratio , of two peaks (shown in Figure f), whose intensities are denoted I 0–0 and I 0–1 , which are attributed to the transitions between the ground state and the first two vibronic levels of the excited state. − The spectra, normalized at the 0–1 transition peak intensity to simplify the comparison of the relative 0–0 peak intensities, are shown in Figure f and can be used to evaluate the intrachain interactions of PTB7:PC 71 BM blend films. , The magnitude of the I 0–0 / I 0–1 ratio reflecting the size of the aggregate for PTB7:PC 71 BM:1% DDAB-sGO film is obviously higher than that for pristine PTB7:PC 71 BM film, while the 0–0 peak red-shifts slightly from 682 to 685 nm. We assume that this behavior is due to an increase in the size of the aggregates in the PTB7:PC 71 BM blend films.…”

Section: Resultsmentioning

confidence: 99%

Optimizing the Crystallinity and Phase Separation of PTB7:PC₇₁BM Films by Modified Graphene Oxide

Zheng

Yang

et al. 2018

J. Phys. Chem. C

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A facile method is proposed to obtain modified shorn graphene oxide (DDAB-sGO) with improved dispersion in organic solvents. Didodecyl dimethylammonium bromide (DDAB)-sGO, which exhibits good dispersibility in the nonpolar solvent o-dichlorobenzene, was obtained via the sono-Fenton reaction and DDAB ionic functionalization. DDAB-sGO was used in the preparation of conjugated polymer:fullerene blend composites. UV−visible absorption spectra, steady-state photoluminescence spectra, fluorescence decay, and grazing incidence X-ray scattering measurements were applied to characterize morphologies, structural features, and charge-transport characteristics of the composites. Doped into poly [[4,8bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7):[6,6]-phenyl C 71 butyric acid methyl ester (PC 71 BM) conjugated polymer blends, DDAB-sGO is shown to facilitate increased crystallinity and phase separation of PTB7 and PC 71 BM to achieve a more optimal morphology for bulk heterojunction solar cells, resulting in a ∼12% enhancement in power conversion efficiency over the undoped PTB7:PC 71 BM blend.

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Boosting the photovoltaic thermal stability of fullerene bulk heterojunction solar cells through charge transfer interactions

Abstract: Charge transfer interaction of a donor polymer with an appropriate 9-fluorenylidene malononitrile derivative in the active layer leads to profoundly enhanced thermal stability of fullerene-based bulk heterojunction organic solar cells.

Cited by 15 publications

References 41 publications

Enhancing the Efficiency of Organic Photovoltaics by a Photoactive Molecular Mediator

Enhancing the Efficiency of Organic Photovoltaics by a Photoactive Molecular Mediator

Thiophene–Perylenediimide Bridged Dimeric Porphyrin Donors Based on the Donor–Acceptor–Donor Structure for Organic Photovoltaics

Optimizing the Crystallinity and Phase Separation of PTB7:PC₇₁BM Films by Modified Graphene Oxide

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Boosting the photovoltaic thermal stability of fullerene bulk heterojunction solar cells through charge transfer interactions

Abstract: Charge transfer interaction of a donor polymer with an appropriate 9-fluorenylidene malononitrile derivative in the active layer leads to profoundly enhanced thermal stability of fullerene-based bulk heterojunction organic solar cells.

Cited by 15 publications

References 41 publications

Enhancing the Efficiency of Organic Photovoltaics by a Photoactive Molecular Mediator

Enhancing the Efficiency of Organic Photovoltaics by a Photoactive Molecular Mediator

Thiophene–Perylenediimide Bridged Dimeric Porphyrin Donors Based on the Donor–Acceptor–Donor Structure for Organic Photovoltaics

Optimizing the Crystallinity and Phase Separation of PTB7:PC71BM Films by Modified Graphene Oxide

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Optimizing the Crystallinity and Phase Separation of PTB7:PC₇₁BM Films by Modified Graphene Oxide