Effects of Bithiophene Imide Fusion on the Device Performance of Organic Thin‐Film Transistors and All‐Polymer Solar Cells

Wang, Yingfeng; Yan, Zhenglong; Guo, Han; Uddin, Mohammad Afsar; Ling, Shaohua; Zhou, Xin; Su, Huimin; Dai, Junfeng; Woo, Han Young; Guo, Xugang

doi:10.1002/anie.201708421

Cited by 160 publications

(115 citation statements)

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“…[29,34] Furthermore, the conjugated length of backbone can precisely lessen the steric hindrance of the adjacent side chain to regulate the crystallinity and intermolecular π-π stacking, resulting in better polymer-small molecular acceptor miscibility and microstructures. [37] In this work, we report a new synthesis method of asymmetric building block TBD containing four fused rings with longer backbone length than BDT unit and shorter than DTBDT unit. [36] During the drying process of the active layer, the poly mer with high crystalline behavior will have a tendency to form large domain size, leading to terrible miscibility.…”

Section: Introductionmentioning

confidence: 99%

A Maverick Asymmetrical Backbone with Distinct Flanked Twist Angles Modulating the Molecular Aggregation and Crystallinity for High Performance Nonfullerene Solar Cells

Wang

Dou

et al. 2018

Advanced Energy Materials

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energy source. [1][2][3][4] The past few years have witnessed the rapid progress of nonfullerene n-type acceptors and the PCE of nonfullerene-based PSCs devices have already surpassed 13% for single-junction devices. [5][6][7][8][9] To achieve efficient nonfullerene PSCs and mature fully from research into cost effective products, it is of critical importance not only to design high-performance small molecular acceptors (SMAs), but also to develop matching donor polymers, as well as to deeply understand the mechanism of the coordinated microstructure interactions between donor and acceptor components. [10][11][12][13][14][15] Key and fundamental strategies for designing high-effciency nonfullerene PSC devices are absorption spectrum and energy level. The donor and acceptor components should possess complementary absorptions and high extinction coefficient to enhance light harvesting to achieve high J SC . [16,17] The matching energy levels are crucial for donor and acceptor to ensure efficient driving force of exciton dissociation, to minimize voltage loss and thus to guarantee high V OC . However, the troublesome tradeoff between high V OC and J SC is inevitable which is the big challenge for further improving the PSCs performance. [18,19] In addition, the most difficult and complicated problem is how to precisely modulate the microstructure of the blending system. The donor should exhibit good morphology compatibility with the acceptor, including suitable crystallinity, appropriate aggregation, face-on orientation, and moderate domain size, and thus to achieve excellent charge transport and high fill factor (FF). [20][21][22] Therefore, establishing universal and general guideline of rational designing compatible D/A structure is extremely urgent and important for nonfullerene PSCs.Benzo[1,2-b:4,5-b′]dithiophene (BDT) and dithieno[2,3d:2′,3′-d′]benzo[1,2-b:4,5-b′]dithiophene (DTBDT) are the dominant backbones for donor polymers because of their planar framework, showing the most high performance in PSCs. [23][24][25][26][27][28][29][30] Most researchers focus on the side chain engineering of BDT-and DTBDT-based polymers and demonstrate that optimized side-chain can easily control polymer packing In this work, a new asymmetrical backbone thienobenzodithiophene (TBD) containing four aromatic rings is designed, and then four polymers PTBD-BZ, PTBD-BDD, PTBD-FBT, and PTBD-Tz are synthesized. The planar and high degree of π-conjugation configuration can guarantee effective charge carrier transport and the distinct flanked dihedral angles between the TBD core and conjugated side chain can subtly regulate the molecular aggregation and crystallinity. The four polymer/3,9-bis(2-methylene-(3-(1,1dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]-dithiophene (ITIC) blending films exhibit predominantly face-on orientation. The photovoltaic devices based on wide bandgap polymers PTBD-BZ and PTBD-BDD achieve power conversion efficiencies (PCEs) as high as 12.02% and...

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Section: Introductionmentioning

confidence: 99%

A Maverick Asymmetrical Backbone with Distinct Flanked Twist Angles Modulating the Molecular Aggregation and Crystallinity for High Performance Nonfullerene Solar Cells

Wang

Dou

et al. 2018

Advanced Energy Materials

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confidence: 99%

Side‐Chain Impact on Molecular Orientation of Organic Semiconductor Acceptors: High Performance Nonfullerene Polymer Solar Cells with Thick Active Layer over 400 nm

Luo

Sun

Chen

et al. 2018

Advanced Energy Materials

124

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In recent years, n-type organic semiconductor (n-OS) (or called as nonfullerene) acceptors have been gaining their popularity in low production cost, light weight, flexible and large-area applications in polymer solar cells (PSCs) due to their excellent optical absorption, tunable energy levels, facile synthesis, and good solution-processability. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Compared with traditional fullerene acceptors such as [6,6]-phenyl-C61/C71-butyric acid methyl ester (PC 61 BM/PC 71 BM), PSCs based on the n-OS acceptors have shown great potential in device performance and device stability. [14,[17][18][19][20][21][22][23][24][25][26][27][28][29] And the n-OS acceptors-based devices have achieved power conversion efficiency (PCE) as high as over 12%. [30][31][32][33][34][35][36][37][38][39][40][41][42] The rational design of the n-OS acceptors is typically based on molecular packing and orbital energetics strategies that are utilized to effectively alter the extension of π conjugation and frontier orbital energy levels. [43][44][45][46][47] Up to now, great efforts have been devoted to development of building blocks, terminal functional groups and side chains, which can effectively tune the band gap and energy levels of the n-OS acceptors. Among them, relatively little attention have been paid to the sidechain engineering of the n-OS acceptors. [5,[48][49][50][51] In comparison with backbone structure and terminal functional groups manipulation, "side-chain engineering" strategy can not only avoid the time-consuming end-capping deficient group and backbone synthesis, but also can improve the photovoltaic performance of PSCs. [33,49,[52][53][54] In addition, this strategy provides an intuitive approach to study the structure-property relationship for the acceptor with the small alterations of the side-chain structures. Structural modification in sidechains of the acceptor, such as changing in length, position, symmetry, and dimension, can remarkably affect molecular packing and intermolecular interaction. [5,[48][49][50][51] For example, the side-chain isomerization of ITIC (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4hexylphenyl)-dithieno[2,3-d:2,3-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene) with meta-alkyl-phenyl instead of para-alkyl-phenyl led to the acceptor m-ITIC with more evident crystallinity and higher electron mobility; [48] the replacement of the side chains of rigid indacenodithieno[3,2-b]-thiophene (IDTT) core from 4-hexylphenyl to 5-hexylthienyl downshifts the lowest unoccupied molecular orbital (LUMO) energy levels and improves the A new n-type organic semiconductor (n-OS) acceptor IDTPC with n-hexyl side chains is developed. Compared to side chains with 4-hexylphenyl counterparts (IDTCN), such a design endows the acceptor of IDTPC with higher electron mobility, more ordered face-on molecular packing, and lower band gap. Therefore, the IDTPC-based polymer solar cells (PSCs) with a newly developed wide bandgap polymer PTQ10 as donor exhi...

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“…Cyclic voltammetry (CV) measurement was performed to determine the lowest unoccupied molcular orbital (LUMO) and highest occupied molcular orbital (HOMO) levels of s‐FBTI2‐FT (Figure a). The LUMO/HOMO levels were found to be −3.50/−6.08 eV, which are greatly lowered relative to those (−3.30/−5.82 eV, Table ) of s‐BTI2‐FT . The results indicate that F addition on the BTI core could enhance both the electron affinity and interchain packing of s‐FBTI2‐FT, showing the distinctive advantages of the fluorination.…”

Section: Resultsmentioning

confidence: 85%

“…Moreover, the small E loss and FF of the s‐FBTI2‐FT cells demonstrated that there are great potentials for further PCE improvement. For the non‐fluorinated polymer s‐BTI2‐FT, the PTB7‐Th:s‐BTI2‐FT all‐PSCs exhibited very limited performance with a maximum PCE of ≈0.1% under various device fabrication conditions . The results clearly demonstrate that the fluorinated BTI‐based polymer s‐FBTI2‐FT is a promising acceptor for all‐PSCs and fluorination of acceptor moiety in the n‐type polymer is a highly effective strategy for improving the device performance.…”

Section: Resultsmentioning

confidence: 86%

“…In comparison to alternating A‐D type copolymers, this A‐A‐D type polymer has a higher content of acceptor moiety in the backbone, which should promote n‐type performance. For better elucidation of the effects of BTI fluorination on optimizing polymer optoelectronic properties and device performance, the non‐fluorinated BTI‐based polymer analogue s‐BTI2‐FT was also synthesized for comparison. Both polymers show comparable molecular weights (Table ) and good solubility in common organic solvents.…”

Section: Resultsmentioning

confidence: 99%

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Fluorine Substituted Bithiophene Imide‐Based n‐Type Polymer Semiconductor for High‐Performance Organic Thin‐Film Transistors and All‐Polymer Solar Cells

et al. 2018

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Bithiophene imide (BTI) is a promising building block for constructing n‐type organic semiconductors. The β‐positions of thiophene in BTI offer an exceptional opportunity for further structural expansion and optimization. Herein, a novel fluorinated BTI, s‐FBTI2, is designed and successfully synthesized, and its incorporation into a polymer backbone led to the resulting semiconductor s‐FBTI2‐FT with improved polymer backbone planarity enabled by the intramolecular non‐covalent S···F interactions and optimized electronic structure attributed to the high electronegativity of F atoms. When applied in organic thin‐film transistors (OTFTs), s‐FBTI2‐FT shows a unipolar n‐type transport with a remarkable electron mobility approaching 3.0 cm2 V−1 s−1, which is >3‐fold higher than that of the polymer analogue without F. Moreover, all‐polymer solar cells (all‐PSCs) with s‐FBTI2‐FT as the electron acceptor polymer achieve a power conversion efficiency of 6.50% with a remarkably high open‐circuit voltage of 1.04 V, which is substantially greater than that of solar cells based on the nonfluorinated analogue acceptor showing negligible photovoltaic performance. The results demonstrate that s‐FBTI‐FT is one of best‐performing n‐type polymer semiconductors reported till today in terms of both OTFT and all‐PSC performances, and fluorination offers an effective approach for optimizing optoelectronic properties of BTI‐based polymers for device performance improvement.

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Effects of Bithiophene Imide Fusion on the Device Performance of Organic Thin‐Film Transistors and All‐Polymer Solar Cells

Cited by 160 publications

References 43 publications

A Maverick Asymmetrical Backbone with Distinct Flanked Twist Angles Modulating the Molecular Aggregation and Crystallinity for High Performance Nonfullerene Solar Cells

A Maverick Asymmetrical Backbone with Distinct Flanked Twist Angles Modulating the Molecular Aggregation and Crystallinity for High Performance Nonfullerene Solar Cells

Side‐Chain Impact on Molecular Orientation of Organic Semiconductor Acceptors: High Performance Nonfullerene Polymer Solar Cells with Thick Active Layer over 400 nm

Fluorine Substituted Bithiophene Imide‐Based n‐Type Polymer Semiconductor for High‐Performance Organic Thin‐Film Transistors and All‐Polymer Solar Cells

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