Naphthobistriazole-based wide bandgap donor polymers for efficient non-fullerene organic solar cells: Significant fine-tuning absorption and energy level by backbone fluorination

Tang, Dongsheng; Wan, Jiahui; Xu, Xiaopeng; Lee, Young Woong; Woo, Han Young; Feng, Kui; Peng, Qiang

doi:10.1016/j.nanoen.2018.08.059

Cited by 38 publications

(26 citation statements)

References 55 publications

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“…Apart from the advantages discussed above, the enhanced electron deficit of TZNT could also lower the HOMO level of the resulting copolymers, contributing to high V oc s and PCEs in fullerene PSCs (Dong et al., 2013, Lan et al., 2015). Apart from the above two reports, most recently, a high PCE of over 10% for a new TZNT-based copolymer of PDTF-TZNT has been first realized in NF-PSCs by our group (Tang et al., 2018b). However, the relatively high HOMO level (−5.24 eV) caused by the strong electron-donating donor block of thiophene led to low V oc (0.8 V) and large energy loss (E loss = 0.8 eV, defined as E loss = E g opt – q V oc , where E g opt is the optical band gap and q is the elementary charge).…”

Section: Introductionmentioning

confidence: 98%

Low-Energy-Loss Polymer Solar Cells with 14.52% Efficiency Enabled by Wide-Band-Gap Copolymers

Feng

Yuan

et al. 2019

iScience

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SummaryTwo wide band-gap copolymers poly[4,8-bis(5-(2-butylhexylthio)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-TZNT] (PBDTS-TZNT) and poly[4,8-bis(4-fluoro-5-(2-butylhexylthio)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-TZNT] (PBDTSF-TZNT) based on naphtho[1,2-c:5,6-c]bis(2-octyl-[1,2,3]triazole) (TZNT) and benzo[1,2-b:4,5-b']dithiophene (BDT) with different conjugated side chains have been developed for efficient nonfullerene polymer solar cells (NF-PSCs). The rigid planar backbone of BDT and TZNT units imparted high crystallinity and good molecular stacking property to these copolymers. Using 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]-dithiophene (ITIC) as the acceptor, PBDTSF-TZNT devices showed a high Voc of 0.98 V with an Eloss of 0.61 eV. On selecting 3,9-bis(2-methylene-(5,6-difluoro-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b’]-dithiophene (IT-4F) instead of ITIC, the devices maintained the high Voc of 0.93 V with an even lower Eloss of 0.59 eV. The combination of the above-mentioned low Eloss, broadened absorption, better matched energy level, improved crystallinity, and fine-tuned morphology promoted the power conversion efficiency (PCE) of PBDTSF-TZNT:IT-4F devices from 12.16% to 13.25%. Homo-tandem devices based on PBDTSF-TZNT:IT-4F subcells further enhanced the light-harvesting ability and boosted the PCE of 14.52%, which is the best value for homo-tandem NF-PSCs at present.

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Section: Introductionmentioning

confidence: 98%

Low-Energy-Loss Polymer Solar Cells with 14.52% Efficiency Enabled by Wide-Band-Gap Copolymers

Feng

Yuan

et al. 2019

iScience

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“…[ 18 ] It should be kept in mind that morphology of ternary active layers plays a vital role in determining the performance of ternary OSCs, the morphology of active layers can be finely adjusted by altering the third component content due to the good compatibility among the used materials. [ 19,20 ] Meanwhile, the third component should have similar lowest unoccupied molecular orbital (LUMO) or the highest occupied molecular orbital (HOMO) levels compared with the host acceptor or donor for efficient charge transport in ternary active layers. [ 21,22 ] The versatile non‐fullerene materials provide great opportunity to recombine the advantages of three materials and the corresponding binary OSCs into one cell for performance improvement, also keeping simple device fabrication process.…”

Section: Introductionmentioning

confidence: 99%

Over 15.7% Efficiency of Ternary Organic Solar Cells by Employing Two Compatible Acceptors with Similar LUMO Levels

Yang

Gao

et al. 2020

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Efficient organic solar cells (OSCs) are fabricated using polymer PM6 as donor, and IPTBO‐4Cl and MF1 as acceptors. The power conversion efficiency (PCE) of IPTBO‐4Cl based and MF1 based binary OSCs individually arrive to 14.94% and 12.07%, exhibiting markedly different short circuit current density (JSC) of 23.18 mA cm−2 versus 17.01 mA cm−2, fill factor (FF) of 72.17% versus 78.18% and similar open circuit voltage (VOC) of 0.893 V versus 0.908 V. The two acceptors, IPTBO‐4Cl and MF1, have similar lowest unoccupied molecular orbital levels, which is beneficial for efficient electron transport in the ternary active layer. The PCE of optimized ternary OSCs arrives to 15.74% by incorporating 30 wt% MF1 in acceptors, resulting from the simultaneously increased JSC of 23.20 mA cm−2, VOC of 0.897 V, and FF of 75.64% in comparison with IPTBO‐4Cl based binary OSCs. The gradually increased FFs of ternary OSCs indicate the well‐optimized phase separation and molecular arrangement with MF1 as morphology regulator. This work may provide a new viewpoint for selecting an appropriate third component to achieve efficient ternary OSCs from materials and photovoltaic parameters of two binary OSCs.

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“…To understand the charge recombination processes, the J sc and V oc values of the NF‐PSCs with Bipy additive were measured and plotted against the light intensity ( P light ) ( Figure a,b) . The relationship between J sc and P light could be explained by the power‐law equation J sc ∝ P light α .…”

Section: Resultsmentioning

confidence: 99%

Achieving a High Fill Factor and Stability in Perylene Diimide–Based Polymer Solar Cells Using the Molecular Lock Effect between 4,4′‐Bipyridine and a Tri(8‐hydroxyquinoline)aluminum(III) Core

Zhang

Lee

et al. 2019

Adv Funct Materials

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Two novel perylene diimide (PDI)-based derivatives, Alq 3 -PDI and Alq 3 -PDI2, are synthesized by flanking a 3D tri(8-hydroxyquinoline)aluminum(III) (Alq 3 ) core with PDI and a helical PDI dimer (PDI2) to construct high-performance small molecular nonfullerene acceptors (SMAs). The 3D Alq 3 core significantly suppresses the molecular aggregation of the resulting SMAs, leading to a well-mixed blend with a PTTEA donor polymer and weak phase separation. Compared with Alq 3 -PDI, the extended π-conjugation of Alq 3 -PDI2 results in higher-order molecular packing, which improves the absorption and phase separation behavior. Thus, the Alq 3 -PDI2 devices have higher J sc and FF values and better device performance, which are further enhanced by a small amount of 4,4′-bipyridine (Bipy) as an additive. The coordination between Bipy and the Alq 3 core promotes molecular packing and phase separation, which lower charge recombination and enhanced charge collection in the resulting devices. Therefore, a largely improved J sc of 15.74 mA cm −2 and very high FF of 71.27% are obtained in the Alq 3 -PDI2 devices, resulting in a power conversion efficiency of 9.54%, which is the best value reported for PDI-based polymer solar cells. The coordination can also serve as a "molecular lock," which prevents molecular motion and thus improves device stability.

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Naphthobistriazole-based wide bandgap donor polymers for efficient non-fullerene organic solar cells: Significant fine-tuning absorption and energy level by backbone fluorination

Cited by 38 publications

References 55 publications

Low-Energy-Loss Polymer Solar Cells with 14.52% Efficiency Enabled by Wide-Band-Gap Copolymers

Low-Energy-Loss Polymer Solar Cells with 14.52% Efficiency Enabled by Wide-Band-Gap Copolymers

Over 15.7% Efficiency of Ternary Organic Solar Cells by Employing Two Compatible Acceptors with Similar LUMO Levels

Achieving a High Fill Factor and Stability in Perylene Diimide–Based Polymer Solar Cells Using the Molecular Lock Effect between 4,4′‐Bipyridine and a Tri(8‐hydroxyquinoline)aluminum(III) Core

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