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Journal ArticleDOI: 10.1021/JACS.0C12818

Carbon-Bridged 1,2-Bis(2-thienyl)ethylene: An Extremely Electron Rich Dithiophene Building Block Enabling Electron Acceptors with Absorption above 1000 nm for Highly Sensitive NIR Photodetectors

04 Mar 2021-Journal of the American Chemical Society (American Chemical Society)-Vol. 143, Iss: 11, pp 4281-4289
Abstract: The emerging donor-acceptor-donor (A-D-A)-type nonfullerene acceptors (NFAs) featuring near-infrared (NIR) photoresponsivity have greatly boosted the development of organic photovoltaics (OPVs) and display great potential for sensitive NIR organic photodetectors (OPDs). However, NIR NFAs with absorption above 1000 nm, which is of great importance for application in NIR OPDs for bioimaging, remote communication, night surveillance, etc., are still rare due to the scarcity of strong electron-rich cores. We report herein a new dithiophene building block, namely PDT, which exhibits the strongest electron-donating ability among the widely used dithiophene building blocks. By applying PDT and PDTT as the electron-donating cores and DFIC as the electron-accepting terminals, we developed two new NIR electron acceptors, PDTIC-4F and PDTTIC-4F, with optical absorptions up to 1030 nm, surpassing that of the well-known O6T-4F acceptor. In comparison with the carbon-oxygen-bridged core COi8 in O6T-4F, the synthetic complexity of PDT and PDTT is significantly reduced. Conventional OPV devices based on PM6:PDTTIC-4F display power conversion efficiencies (PCEs) of up to 10.70% with a broad external quantum efficiency (EQE) response from the ultraviolet-visible to the infrared, leading to a high short-circuit current density (Jsc) of 25.90 mA cm-2. Encouraged by these results, we investigated inverted PM6:PDTTIC-4F-based OPD devices by suppressing the dark current via modulation of the film thickness. The optimal OPD device exhibits compelling performance metrics that can compete with those of commercial silicon photodiodes: a record responsivity of 0.55 A W-1 (900 nm) among photodiode-type OPDs and excellent shot-noise-limited specific detectivity (Dsh*) of over 1013 jones.

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8 results found

Journal ArticleDOI: 10.1002/ANIE.202104766
Can Yang1, Qiaoshi An1, Hai-rui Bai1, Hong-Fu Zhi1  +6 moreInstitutions (2)
23 Aug 2021-Angewandte Chemie
Abstract: A dissymmetric backbone and selenophene substitution on the central core was used for the synthesis of symmetric or dissymmetric A-DA'D-A type non-fullerene small molecular acceptors (NF-SMAs) with different numbers of selenophene. From S-YSS-Cl to A-WSSe-Cl and to S-WSeSe-Cl, a gradually red-shifted absorption and a gradually larger electron mobility and crystallinity in neat thin film was observed. A-WSSe-Cl and S-WSeSe-Cl exhibit stronger and tighter intermolecular π-π stacking interactions, extra S⋅⋅⋅N non-covalent intermolecular interactions from central benzothiadiazole, better ordered 3D interpenetrating charge-transfer networks in comparison with thiophene-based S-YSS-Cl. The dissymmetric A-WSSe-Cl-based device has a PCE of 17.51 %, which is the highest value for selenophene-based NF-SMAs in binary polymer solar cells. The combination of dissymmetric core and precise replacement of selenophene on the central core is effective to improve Jsc and FF without sacrificing Voc .

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Topics: Polymer solar cell (52%)

19 Citations

Open accessJournal ArticleDOI: 10.1038/S41467-021-25394-W
Lijiao Ma1, Shaoqing Zhang2, Jincheng Zhu2, Jingwen Wang1  +3 moreInstitutions (3)
Abstract: Non-fullerene acceptors (NFAs) based on non-fused conjugated structures have more potential to realize low-cost organic photovoltaic (OPV) cells. However, their power conversion efficiencies (PCEs) are much lower than those of the fused-ring NFAs. Herein, a new bithiophene-based non-fused core (TT-Pi) featuring good planarity as well as large steric hindrance was designed, based on which a completely non-fused NFA, A4T-16, was developed. The single-crystal result of A4T-16 reveals that a three-dimensional interpenetrating network can be formed due to the compact π–π stacking between the adjacent end-capping groups. A high PCE of 15.2% is achieved based on PBDB-TF:A4T-16, which is the highest value for the cells based on the non-fused NFAs. Notably, the device retains ~84% of its initial PCE after 1300 h under the simulated AM 1.5 G illumination (100 mW cm−2). Overall, this work provides insight into molecule design of the non-fused NFAs from the aspect of molecular geometry control. Non-fullerene acceptors based on non-fused conjugated structures have potential for realizing low-cost organic photovoltaic cells, owing to its synthetic simplicity. Here, the authors develop a non-fused molecule with a three-dimensional interpenetrating network and compact π-π stacking, which is highly suitable for PV applications.

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Topics: Organic solar cell (54%), Stacking (52%)

3 Citations

Journal ArticleDOI: 10.1016/J.MATTOD.2021.08.004
Junwei Liu1, Junwei Liu2, Mengyuan Gao2, Juhee Kim3  +5 moreInstitutions (4)
11 Sep 2021-Materials Today
Abstract: Organic photodetectors (OPDs) have drawn extensive research efforts due to their tailorable spectral response, ease of processing, compatibility with flexible devices and cooling-free operations. In this review, we outline the promising strategies for constructing high-performance and highly stable photodiodes-based OPDs from the perspectives of molecular engineering, morphology control, and device structure design. Firstly, the impact of molecular design and morphology control on OPD performance is clearly underlined and the molecular design rules and quantitative analysis methods are presented for high-performance OPDs. Subsequently, some striking device designs for multifunctional applications are discussed to elucidate the corresponding mechanism for various responses. What follows are the research efforts of boosting OPD stability for commercial applications. This review not only presents the detailed discussion on various OPD strategies aiming at simultaneously enhancing performance and stability but also provides some insights for the remaining challenges to make further breakthrough of OPDs.

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2 Citations

Journal ArticleDOI: 10.1021/JACS.1C03394
Abstract: Carbon bridging in a form of a strained 1,4-dihydropentalene framework is an effective strategy for flattening and stabilizing oligophenylenevinylene systems for the development of optoelectronic materials. However, efficient and flexible methods for making such a strained ring system are lacking. We report herein a mild and versatile synthetic access to the 1,4-dihydropentalene framework enabled by iron-catalyzed single-pot tandem cyclization of a diarylacetylene using FeCl2 and PPh3 as catalyst, magnesium/LiCl as a reductant, and 1,2-dichloropropane as a mild oxidant. The new annulation method features two iron-catalyzed transformations used in tandem, a reductive acetylenic carboferration and an oxidation-induced ring contraction of a ferracycle under mild oxidative conditions. The new method provides access not only to a variety of substituted indeno[2,1-a]indenes but also to their thiophene congeners, 4,9-dihydrobenzo[4,5]pentaleno[1,2-b]thiophene (CPTV) and 4,8-dihydropentaleno[1,2-b:4,5-b']dithiophenes (CTV). With its high highest occupied molecular orbital level and narrow optical gap, CTV serves as a donor unit in a narrow-band-gap non-fullerene acceptor, which shows absorption extending over 1000 nm in the film state, and has found use in a near-infrared photodetector device that exhibited an external quantum efficiency of 72.4% at 940 nm.

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Topics: Annulation (52%), Thiophene (51%)

2 Citations

Journal ArticleDOI: 10.1021/ACSAMI.1C18673
Jianpeng Ma1, Jianpeng Ma2, Hanfei Gao2, Jiangang Feng3  +5 moreInstitutions (5)
Abstract: Structural design of organic π-conjugated small molecules allows the energy band structure and electronic properties of the molecules to be tuned as needed, which provides a feasible strategy for enhancing the performance of optoelectronic devices. The introduction of bridging structures is a common structural modification method to adjust the rigidity and coplanarity of the molecular backbone, thus affecting the molecular packing. However, patterning of organic single-crystalline microstructures based on conjugated ladder molecules with different bridging structures still remains challenging for large-area integration of optoelectronic devices. In this paper, a controlled dewetting process is applied to obtain organic single-crystalline arrays with precise positioning and a regular morphology based on two isomers with silicon-oxygen bridging and their two carbon-oxygen-bridged analogues. Molecules with different bridging structures show disparate packing models due to the difference of dihedral angles and ring tensions. A microwire-array ultraviolet photodetector based on the oxygen-silicon-bridging ladder molecule exhibits a high light on/off ratio of 24 and a responsivity of 0.63 mA W-1 owing to the effective π-π stacking governed by the molecular planarity. This work not only provides a universal method for the integration of organic optoelectronic devices but also explains the effect of bridging structure engineering on molecular assembly and optoelectronic performance.

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Topics: Bridging (networking) (52%)


63 results found

Journal ArticleDOI: 10.1002/ADMA.201404317
Yuze Lin1, Jiayu Wang2, Zhi-Guo Zhang1, Huitao Bai1  +3 moreInstitutions (2)
01 Feb 2015-Advanced Materials
Abstract: A novel non-fullerene electron acceptor (ITIC) that overcomes some of the shortcomings of fullerene acceptors, for example, weak absorption in the visible spectral region and limited energy-level variability, is designed and synthesized. Fullerene-free polymer solar cells (PSCs) based on the ITIC acceptor are demonstrated to exhibit power conversion effi ciencies of up to 6.8%, a record for fullerene-free PSCs.

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Topics: Polymer solar cell (56%), Acceptor (55%), Electron acceptor (54%)

2,278 Citations

Open accessJournal ArticleDOI: 10.1016/J.JOULE.2019.01.004
Jun Yuan1, Yunqiang Zhang1, Liuyang Zhou1, Liuyang Zhou2  +13 moreInstitutions (6)
17 Apr 2019-Joule
Abstract: Summary Recently, non-fullerene n-type organic semiconductors have attracted significant attention as acceptors in organic photovoltaics (OPVs) due to their great potential to realize high-power conversion efficiencies. The rational design of the central fused ring unit of these acceptor molecules is crucial to maximize device performance. Here, we report a new class of non-fullerene acceptor, Y6, that employs a ladder-type electron-deficient-core-based central fused ring (dithienothiophen[3.2-b]- pyrrolobenzothiadiazole) with a benzothiadiazole (BT) core to fine-tune its absorption and electron affinity. OPVs made from Y6 in conventional and inverted architectures each exhibited a high efficiency of 15.7%, measured in two separate labs. Inverted device structures were certified at Enli Tech Laboratory demonstrated an efficiency of 14.9%. We further observed that the Y6-based devices maintain a high efficiency of 13.6% with an active layer thickness of 300 nm. The electron-deficient-core-based fused ring reported in this work opens a new door in the molecular design of high-performance acceptors for OPVs.

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Topics: Organic solar cell (54%), Acceptor (52%), Organic semiconductor (51%)

2,112 Citations

Open accessJournal ArticleDOI: 10.1021/ACS.CHEMREV.5B00098
Luyao Lu1, Tianyue Zheng1, Qinghe Wu1, Alexander M. Schneider1  +2 moreInstitutions (1)
07 Aug 2015-Chemical Reviews
Topics: Hybrid solar cell (66%), Polymer solar cell (63%)

1,922 Citations

Open accessJournal ArticleDOI: 10.1126/SCIENCE.AAT2612
Lingxian Meng1, Yamin Zhang1, Xiangjian Wan1, Chenxi Li1  +9 moreInstitutions (3)
14 Sep 2018-Science
Abstract: Although organic photovoltaic (OPV) cells have many advantages, their performance still lags far behind that of other photovoltaic platforms. A fundamental reason for their low performance is the low charge mobility of organic materials, leading to a limit on the active-layer thickness and efficient light absorption. In this work, guided by a semi-empirical model analysis and using the tandem cell strategy to overcome such issues, and taking advantage of the high diversity and easily tunable band structure of organic materials, a record and certified 17.29% power conversion efficiency for a two-terminal monolithic solution-processed tandem OPV is achieved.

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Topics: Photovoltaic system (51%), Tandem (50%)

1,805 Citations

Journal ArticleDOI: 10.1002/ADMA.201304373
Alan J. Heeger1Institutions (1)
01 Jan 2014-Advanced Materials
Abstract: The status of understanding of the operation of bulk heterojunction (BHJ) solar cells is reviewed. Because the carrier photoexcitation recombination lengths are typically 10 nm in these disordered materials, the length scale for self-assembly must be of order 10–20 nm. Experiments have verified the existence of the BHJ nanostructure, but the morphology remains complex and a limiting factor. Three steps are required for generation of electrical power: i) absorption of photons from the sun; ii) photoinduced charge separation and the generation of mobile carriers; iii) collection of electrons and holes at opposite electrodes. The ultrafast charge transfer process arises from fundamental quantum uncertainty; mobile carriers are directly generated (electrons in the acceptor domains and holes in the donor domains) by the ultrafast charge transfer (≈70%) with ≈30% generated by exciton diffusion to a charge separating heterojunction. Sweep-out of the mobile carriers by the internal field prior to recombination is essential for high performance. Bimolecular recombination dominates in materials where the donor and acceptor phases are pure. Impurities degrade performance by introducing Shockly–Read–Hall decay. The review concludes with a summary of the problems to be solved to achieve the predicted power conversion efficiencies of >20% for a single cell.

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Topics: Heterojunction (55%), Photoinduced charge separation (55%), Polymer solar cell (53%) ... read more

1,312 Citations