Effect of main and side chain chlorination on the photovoltaic properties of benzodithiophene-<i>alt</i>-benzotriazole polymers

Bin, Haijun; Angunawela, Indunil; Ma, Ruijie; Nallapaneni, Asritha; Zhu, Chenhui; Leenaers, Pieter J.; Saes, Bart W. H.; Wienk, Martijn M.; Yan, He; Ade, Harald; Janssen, Raj René

doi:10.1039/d0tc03095c

Cited by 13 publications

(12 citation statements)

References 69 publications

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“…Thus, we can draw a conclusion from the DMTA and GIWAXS results that our new polymers are completely amorphous. In order to compare PIDT-TXBT with the reported high-performing donor polymers, we also performed DMTA measurement on PM6 and J71 (DMA plots shown in the Supporting Information, Figure S18). However, these two high-performing donor polymers only show sub- T g transitions and no detectable T g , which we believe is a result of the “hairy aggregates” phase described in our previous work .…”

Section: Resultsmentioning

confidence: 99%

Achieving High-Efficiency Organic Photovoltaics from a New Completely Amorphous Donor Polymer

et al. 2022

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The development of non-fullerene acceptors (NFAs) such as ITIC and Y6 has greatly improved the efficiency of polymer solar cells. Therefore, focus should now shift towards the design of donor polymers with better compatibility with these NFAs to attempt to push efficiencies to higher levels. The indacenodithienothiophene (IDT) unit has up till now been typically incorporated into donor polymers for fullerene-based solar cells; however, the application of IDT-based polymers in NFA solar cells is rare. In order to increase the number of donor polymer candidates, we have synthesized two new polymers PIDT-T8BT and PIDT-T12BT conjugating IDT and perfluorinated benzothiadiazole moieties through octyl and dodecyl thiophene bridging units, respectively. These polymers were studied and revealed to be completely amorphous without aggregates, and their glass transition temperatures were distinct owing to the different lengths of the alkyl groups attached to the thiophene units. In addition, the length of the side groups greatly affects the solar cell performance. The longer dodecyl side groups in the polymer PIDT-T12BT resulted in a lower glass transition temperature and favorable thermal annealing conditions of the active layer blend with Y6. A promising power conversion efficiency of over 12% was achieved for PIDT-T12BT when paired with the Y6 acceptor and thermally annealed at 170 °C, which is the highest reported value so far for IDT-based donor polymers.

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Section: Resultsmentioning

confidence: 99%

Achieving High-Efficiency Organic Photovoltaics from a New Completely Amorphous Donor Polymer

et al. 2022

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“…By comparing device performance and stability of the SM‐OSCs with/without PDINO within these two different active layers (Figure S14 and Table S3, Supporting Information), we found the ETL‐free devices show comparable initial device performance and better device stability, indicating that well performing the ETL‐free SM‐OSCs is not restricted to the H31 :Y6 combination studied here in detail. We also investigated the device performance of PSCs based on blends of two polymers, J71‐Cl and J101 [ 54 ] (structures shown in Figure S15 in the Supporting Information), with 9‐bis(2‐methylene‐((3‐(1,1‐dicyanomethylene)‐6,7‐difluoro)‐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) as NFA with and without PDINO and found that both PSCs show lower PCEs without PDINO (Figure S16 and Table S4, Supporting Information). This demonstrates that PDINO enhances the PCE in these PSCs.…”

Section: Resultsmentioning

confidence: 99%

“…By comparing device performance and stability of the SM-OSCs with/without PDINO within these two different active layers (Figure S14 and Table S3, Supporting Information), we found the ETL-free devices show comparable initial device performance and better device stability, indicating that well performing the ETL-free SM-OSCs is not restricted to the H31:Y6 combination studied here in detail. We also investigated the device performance of PSCs based on blends of two polymers, J71-Cl and J101 [54] (structures shown in Figure S15 dithiophene-4,8-dione)] (PM6) and Y6. [38] This shows that omitting the ETL affects the initial performance in these PSCs negatively.…”

Section: Resultsmentioning

confidence: 99%

Efficient Electron Transport Layer Free Small‐Molecule Organic Solar Cells with Superior Device Stability

Bin

Wang

et al. 2021

Advanced Materials

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Electron transport layers (ETLs) placed between the electrodes and a photoactive layer can enhance the performance of organic solar cells but also impose limitations. Most ETLs are ultrathin films, and their deposition can disturb the morphology of the photoactive layers, complicate device fabrication, raise cost, and also affect device stability. To fully overcome such drawbacks, efficient organic solar cells that operate without an ETL are preferred. In this study, a new small‐molecule electron donor (H31) based on a thiophene‐substituted benzodithiophene core unit with trialkylsilyl side chains is designed and synthesized. Blending H31 with the electron acceptor Y6 gives solar cells with power conversion efficiencies exceeding 13% with and without 2,9‐bis[3‐(dimethyloxidoamino)propyl]anthra[2,1,9‐def:6,5,10‐d′e′f ′]diisoquinoline‐1,3,8,10(2H,9H)‐tetrone (PDINO) as the ETL. The ETL‐free cells deliver a superior shelf life compared to devices with an ETL. Small‐molecule donor–acceptor blends thus provide interesting perspectives for achieving efficient, reproducible, and stable device architectures without electrode interlayers.

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“…The sub-nanometer surface roughness found for J71:ITIC (R q ¼ 0.55 nm) and J71:IT-4F (R q ¼ 0.80 nm) agrees well with previously reported data for these blends of 0.72 and 0.74 nm, respecively. 41,45 Compared to the J77-based blend films, the R q values of the J71-based blend film are thus slightly lower, but the difference is very small. This suggests that similar nanophase morphology is obtained with triisobutylsilyl side chains as with tripropylsilyl side chains.…”

Section: Resultsmentioning

confidence: 96%

Efficient Solar Cells Based on a Polymer Donor with β-Branching in Trialkylsilyl Side Chains

2021

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Side-chain engineering is an important strategy in designing novel polymer semiconductor materials for high-efficient organic solar cells. The use of trialkylsilyl side chains can improve the photovoltaic efficiency by decreasing the energy of the HOMO of the polymer and improving its crystallinity and hole mobility. Compared to simple linear derivatives, α-branching in the alkyl groups of trialkylsilyl side chains causes strong aggregation and excessive phase separation in the photoactive layer, leading to poor device performance. β-Branching of the alkyl groups has not yet been used in trialkylsilyl side chains. Herein, we describe a new polymer (J77) with triisobutylsilyl side chains to investigate the effect of β-branching on the molecular aggregation, optical properties, energy levels, and photovoltaic properties. We find that compared to α-branching, β-branching of alkyl groups in trialkylsilyl side chains significantly reduces aggregation. This enables J77 to form blend morphologies in films that provide high-efficient solar cells in combination with different non-fullerene acceptors. Moreover β-branching of the alkyl groups in trialkylsilyl side chains lowers the HOMO energy level of J77 and increases the open-circuit voltage of J77-based solar cells without sacrificing short-circuit current density or fill factor.

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Effect of main and side chain chlorination on the photovoltaic properties of benzodithiophene-alt-benzotriazole polymers

Abstract: In developing organic semiconductor polymers for photovoltaic applications, chlorine substitution has become an effective strategy in replacing fluorine substitution to overcome the drawbacks of low yield and high cost, commonly...

Cited by 13 publications

References 69 publications

Achieving High-Efficiency Organic Photovoltaics from a New Completely Amorphous Donor Polymer

Achieving High-Efficiency Organic Photovoltaics from a New Completely Amorphous Donor Polymer

Efficient Electron Transport Layer Free Small‐Molecule Organic Solar Cells with Superior Device Stability

Efficient Solar Cells Based on a Polymer Donor with β-Branching in Trialkylsilyl Side Chains

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