Fluorination effects of A-D-A-type small molecules on physical property and the performance of organic solar cell

Chen, Ko-Wei; Lin, Li‐Yen; Li, Yihua; Li, Ya‐Ze; Nguyen, Thanh Phuc; Biring, Sajal; Liu, Shun‐Wei; Wong, Ken‐Tsung

doi:10.1016/j.orgel.2017.11.021

Cited by 18 publications

(5 citation statements)

References 72 publications

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“…The lower R CT value is observed for RSeT:PC 61 BM (1:3, w/w), suggesting less recombination of charges which is in line with the improved charge transportability in BHJ‐OSCs and enhances the FF and V oc. 76,77 In support, the small impedance value in imaginary is observed in the case of RSeT:PC 61 BM (1:3, w/w), indicating the high interface capacitance in donor/acceptor active layer that clearly reflects the good electrical behavior in the homogenous manner of BHJ layer.…”

Section: Resultsmentioning

confidence: 86%

“…The purpose of semilog plots of J sc and V oc vs light intensity is to evaluate the ideality factor from the slope of Figure 5. In general, the ideality factor from semilog plots is 1 which explains the dominance of bimolecular recombination, whereas the ideality factor 2 describes the dominance of monomolecular recombination 76,77 . From Figure 5A, the estimated ideality factor is ~1.01, suggesting the recombination–loss mechanisms with the increase of light intensity by the dominance of bimolecular recombination.…”

Section: Resultsmentioning

confidence: 95%

“…In general, the ideality factor from semilog plots is 1 which explains the dominance of bimolecular recombination, whereas the ideality factor 2 describes the dominance of monomolecular recombination. 76,77 From Figure 5A, the estimated ideality factor is $1.01, suggesting the recombination-loss mechanisms with the increase of light intensity by the dominance of bimolecular recombination. However, a similar discrepancy feature is not observed in Figure 5B.…”

Section: Photovoltaic Results and Device Stability Testmentioning

confidence: 99%

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Highly stable bulk heterojunction organic solar cells based on asymmetric benzoselenadiazole‐oriented organic chromophores

Abdullah

Kim

Akhtar

et al. 2022

Intl J of Energy Research

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Summary A new asymmetrically designed D‐A‐D organic chromophore 4‐(7‐(5′‐hexyl‐[2,2′‐bithiophen]‐5‐yl)benzo[c][1,2,5]selenadiazol‐4‐yl)‐N,N‐diphenylaniline (RSeT) with benzoselenadiazole acceptor unit has been synthesized using two different electron donor materials of triphenylamine (TPA) and n‐hexyl bithiophene unit. Attachment of nonplanar electron‐donating TPA unit subsequently heightened the optoelectronic properties and altered the solubility in organic solvents. RSeT of the optical bandgap of ~1.95 eV with the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of −5.31 and −3.36 eV was applied as an electron donor material for stable bulk heterojunction organic solar cells. In this work, two different buffer layers of poly (3, 4‐ethylenedioxythiophene):polystyrene sulfonate acid (PEDOT:PSS) and compact titanium oxide (c‐TiO2) were used and their influences on the device performance were investigated. Buffer layer of c‐TiO2 with RSeT:PC61BM (1:3, w/w) active layer achieved a high open‐circuit voltage (Voc) of ~0.985 V, short‐circuit current density (Jsc) of ~11.26 mA/cm2 and improved fill factor of ~0.62 which resulted in a high power conversion efficiency (PCE) of ~6.88%. After 30 days, interestingly, RSeT:PC61BM (1:3, w/w) devices with a c‐TiO2 buffer layer demonstrated good stability with the PCE value remaining at 85% of its initial value.

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Section: Resultsmentioning

confidence: 86%

Section: Resultsmentioning

confidence: 95%

Section: Photovoltaic Results and Device Stability Testmentioning

confidence: 99%

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Highly stable bulk heterojunction organic solar cells based on asymmetric benzoselenadiazole‐oriented organic chromophores

Abdullah

Kim

Akhtar

et al. 2022

Intl J of Energy Research

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“…In addition, F substitution can induce extra intra- and intermolecular interactions through C–F···H, F···S, and C–F···π weak bonding interactions to change the molecular conformation as well as bulk morphology . The FBT-embedded polymer − and small-molecule , donors have been reported to show the capability of tuning physical properties and enhancing device performances by employing different numbers and relative orientations of F substitution(s) within the π-conjugated backbone. Along this line, two new molecules, DTCFiBT and DTCFoBT, with mono-F-substituted BT and one new molecule, DTCF2BT, with di-F-substituted BT as the A group of D–A–A′ architecture were synthesized and characterized to study the effects of the F-substituted BT orientation relative to the D group and the number of F substitution on the physical properties, intermolecular interactions, and device performances.…”

Section: Introductionmentioning

confidence: 99%

“…For example, a D−A−A′-configured molecule, DTCPB 16 (Scheme 1), in which di(p-tolyl)aminophenyl, benzothiadiazole (BT), and cyano are adopted as D, A, and A′ units, respectively, was reported to have blue-shift absorption compared to that of DTDCPB, having the same D and A but with A′ being dicyanovinylene. 33 34 The FBT-embedded polymer 34−37 and small-molecule 38,39 donors have been reported to show the capability of tuning physical properties and enhancing device performances by employing different numbers 38 and relative orientations 38 ■ RESULTS AND DISCUSSION Synthesis. Scheme 2 depicts the synthesis of F-substituted DTCPB analogues, DTCFiBT, DTCFoBT, and DTCF2BT.…”

Section: ■ Introductionmentioning

confidence: 99%

Harnessing the Inductive Effect To Design New Donor–Acceptor–Acceptor′-Configured Small-Molecule Donors for Vacuum-Processed Organic Photovoltaics

Chen

et al. 2021

Energy Fuels

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Three new donor–acceptor–acceptor′ (D–A–A′)-configured molecules, DTCFiBT, DTCFoBT, and DTCF2BT, with F-substituted benzothiadiazole (BT) as the A group, and two molecules, DTCPiTD and DTCPoTD, adopting pyridal[2,1,3]-thiadiazole (PTD) as the A group, were synthesized and characterized. The effects of the F-substitution number and the orientation of mono F-substituted BT and PTD relative to the D group on the physical properties and intermolecular interactions were examined, together with theoretical calculations to establish the structure–property relationship. In comparison to the parent molecule DTCPB, the inductive effects of F-substituted BTs lower both highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of DTCFiBT, DTCFoBT, and DTCF2BT and, thus, similar optical energy gaps (E g opt), while DTCPiTD and DTCPoTD exhibit much lower LUMO energy levels and reduced E g opt, ascribing to the electron-deficient character of PTD. The strong dipolar features of the D–A–A′-configured structure resulting in the antiparallel dimeric packing with different intermolecular interactions in their crystal structures were observed by X-ray analyses. Small-molecule organic solar cells (SMOSCs) with a bulk heterojunction active layer comprising new D–A–A′ donors and C70 were fabricated and characterized. The deeper LUMO levels and reduced E g opt benefit the DTCPiTD- and DTCPoTD-based devices to have higher short current density (J SC), while the DTCFiBT-, DTCFoBT-, and DTCF2BT-based devices benefited from the lower HOMO energy levels that lead to the higher open circuit voltage (V OC). Transient photoluminescence, atomic force microscopy, and incident-light-intensity-dependent device characteristics were examined to reveal the recombination issue for the inferior DTCFoBT-based device. Among these new donors, the DTCFiBT-based device shows the best performance, with V OC of 0.94, J SC of 11.3 mA/cm2, fill factor (FF) of 0.65, and power conversion efficiency of 6.8%, which are attributed to the high V OC as a result of the deeper HOMO level and the superior FF as a result of good exciton separation and charge carrier transport.

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Designing new donor materials based on functionalized DCCnT with different electron‐donating groups: A density functional theory (DFT) and time dependent density functional theory (TDDFT)‐based study

Zheng

2019

Int J of Quantum Chemistry

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Finding a promising donor/acceptor material of organic solar cells is one of the most important ways to improve their power conversion efficiency. Extensive studies have focused on designing and synthesizing new and suitable materials. Small organic molecule materials, different from polymers, have many merits, such as easy synthesis and modification, less by‐products, and crystallinity. In the present work, we theoretically design a series of new donor materials based on 1‐(1,1‐dicyanomethylene)‐cyclohex‐2‐ene‐substituted oligothiophenes, that is, DCCnT (n = 1‐4) series. Furthermore, we model and predict photoelectric properties of functionalized DCCnT with different electron‐donating groups (─CH3/─CHCH2/─OCH3/─NH2/─OH). The calculated results, based on density functional theory and time‐dependent functional theory, show that DCCnT‐X (X = OH, NH2, and OCH3) series show odd‐even effect of dipole moments when n varies from 1 to 4, whereas DCCnT‐CH3 and DCCnT‐CHCH2 do not. Finally, we find that DCC3T‐X (X = OH, OCH3, and NH2) may be better candidates of donor materials because of their larger dipole moments, stronger electron donating ability, and smaller exciton binding energy with respect to prototype DCCnT molecules.

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Fluorination effects of A-D-A-type small molecules on physical property and the performance of organic solar cell

Cited by 18 publications

References 72 publications

Highly stable bulk heterojunction organic solar cells based on asymmetric benzoselenadiazole‐oriented organic chromophores

Highly stable bulk heterojunction organic solar cells based on asymmetric benzoselenadiazole‐oriented organic chromophores

Harnessing the Inductive Effect To Design New Donor–Acceptor–Acceptor′-Configured Small-Molecule Donors for Vacuum-Processed Organic Photovoltaics

Designing new donor materials based on functionalized DCCnT with different electron‐donating groups: A density functional theory (DFT) and time dependent density functional theory (TDDFT)‐based study

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