Fluorination Triggered New Small Molecule Donor Materials for Efficient As‐Cast Organic Solar Cells

Yang, Yuting; Wang, Kai; Li, Gongqiang; Ran, Xueqin; Song, Xin; Gasparini, Nicola; Zhang, Qianqian; Lai, Xue; Guo, Xiao; Meng, Fanning; Du, Mengzhen; Huang, Wei; Baran, Derya

doi:10.1002/smll.201801542

Cited by 26 publications

(15 citation statements)

References 57 publications

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“…crystallinity and facilitate charge transport. [22][23][24][25][26][27][28] Moreover, comparing the 1,1-dicyanomethylene-3-indanone (IC) endgroup with its fluorinated derivative 2-(5,6-difluoro-3oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (IC-4F), the stronger electron-withdrawing effect of the latter can enhance intramolecular charge transfer (ICT) in NFA materials resulted in a red-shift of the absorption spectra of NFAs to the near-IR region, thus enhancing device photocurrent. Several studies have demonstrated that OSCs based on ladder type NFAs with fluorinated endgroups show improved device performance than those based on non-fluorinated counterparts.…”

Section: Intramolecular Interactions Through Noncovalent C−f•••s and mentioning

confidence: 99%

Crucial Role of Fluorine in Fully Alkylated Ladder-Type Carbazole-Based Nonfullerene Organic Solar Cells

Shahid

Jiao

et al. 2020

ACS Appl. Mater. Interfaces

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Two fused ladder type non-fullerene acceptors, DTCCIC and DTCCIC-4F, based on an electron-donating alkylated dithienocyclopentacarbazole core flanked by electron-withdrawing non-fluorinated or fluorinated 1,1dicyanomethylene-3-indanone (IC or IC-4F), are prepared and utilized in organic solar cells (OSCs). The two new molecules reveal planar structures and strong aggregation behavior, and fluorination is shown to red shift the optical band gap and down shift energy levels. OSCs based on DTCCIC-4F exhibit a power conversion efficiency of 12.6 %, much higher than that of DTCCIC based devices (6.2 %). Microstructural studies reveal that while both acceptors are highly crystalline, bulk heterojunction blends based on the non-fluorinated DTCCIC result in overly coarse domains, while blends based on the fluorinated DTCCIC-4F exhibit a more optimal nanoscale morphology. These results highlight the importance of end group fluorination in controlling molecular aggregation and miscibility.

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Section: Intramolecular Interactions Through Noncovalent C−f•••s and mentioning

confidence: 99%

Crucial Role of Fluorine in Fully Alkylated Ladder-Type Carbazole-Based Nonfullerene Organic Solar Cells

Shahid

Jiao

et al. 2020

ACS Appl. Mater. Interfaces

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“…For instance, PCE improvements can clearly be seen in the cases of IDT‐T (6.28%) versus IDTT2F (8.75%), INPIC (4.31%) versus INPIC‐4F (13.13%), IDT2Se (9.36%) versus IDT2Se‐4F (11.19%), ITVIC (7.34%) versus ITVffIC (10.54%), and ITIC (11.05%) versus IT4F (13.10%) . In addition, fluorination on small‐molecule donors also dramatically improves the fullerene‐based ASM OSCs, for example, DI3T (0.83%) versus DI3T (7.80%) and BTID‐0F (8.30%) versus BTID‐2F (11.30%) . However, such a facile yet effective strategy has rarely been applied in FREA‐based ASM OSCs, and the effect of fluorination of FREAs on high‐performance ASM OSCs is still unclear and requires further investigation.…”

Section: Introductionmentioning

confidence: 99%

Deciphering the Role of Fluorination: Morphological Manipulation Prompts Charge Separation and Reduces Carrier Recombination in All‐Small‐Molecule Photovoltaics

et al. 2020

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Fluorination has proven effective in increasing the absorption, downshifting the energy levels, and enhancing the crystallinity of high‐performance fused‐ring electron acceptors (FREAs). However, an in‐depth understanding of the effects of fluorination is still lacking, as research efforts have mainly focused on increasing the power conversion efficiency (PCE). In addition, fluorination on FREAs has rarely been reported in all‐small‐molecule organic solar cells (ASM OSCs). Herein, fluorination on FREAs is systematically studied in ASM OSCs using the popular FREA 2,2′‐((2Z,2′Z)‐((4,4,9,9‐tetrahexyl‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,7‐diyl)bis(methanylylidene))bis(3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile and its fluorinated analog paired with DRCN5T, an oligothiophene donor seldom investigated in ASM OSCs to date. (Photo)physical studies are conducted on both systems and it is identified that, along with the aforementioned ones, fluorination exerts several additional effects, including the following. First, it optimizes the morphology, thereby accelerating charge separation and reducing geminate recombination charge pairs; second, it suppresses energetic disorder; and third, it prolongs the carrier lifetime and thus aids charge extraction. Consequently, the short‐circuit current density and fill factor are significantly enhanced, and in turn, the PCE yields a 36% improvement, climbing to 9.25% and rivaling that of the current state‐of‐the‐art oligothiophene‐donor/nonfullerene ASM OSCs. The insights decipher the working mechanism of ASM OSCs that use fluorinated FREAs, paving the way toward high‐performance ASM OSCs.

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“…Several groups have reported that the ternary or process‐engineering strategy is useful to fabricate thick active films with good PCEs . To be noted, most of these devices are based on fullerene derivatives (PC 71 BM or PC 61 BM) as electron acceptor on consideration of their excellent electron mobility and isotropic charge transport property.…”

Section: Introductionmentioning

confidence: 99%

Molecular Orientation Unified Nonfullerene Acceptor Enabling 14% Efficiency As‐Cast Organic Solar Cells

Feng

Song

Zhang

et al. 2019

Adv Funct Materials

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Molecular orientation and π-π stacking of nonfullerene acceptors (NFAs) determine its domain size and purity in bulk-heterojunction blends with a polymer donor. Two novel NFAs featuring an indacenobis(dithieno[3,2-b:2′,3′-d] pyrrol) core with meta-or para-alkoxyphenyl sidechains are designed and denoted as m-INPOIC or p-INPOIC, respectively. The impact of the alkoxyl group positioning on molecular orientation and photovoltaic performance of NFAs is revealed through a comparison study with the counterpart (INPIC-4F) bearing para-alkylphenyl sidechains. With inward constriction toward the conjugated backbone, m-INPOIC presents predominant face-on orientation to promote charge transport. The as-cast organic solar cells (OSCs) by blending m-INPOIC and PBDB-T as active layers exhibit a power conversion efficiency (PCE) of 12.1%. By introducing PC 71 BM as the solid processing-aid, the ternary OSCs are further optimized to deliver an impressive PCE of 14.0%, which is among the highest PCEs for as-cast single-junction OSCs reported in literature to date. More attractively, PBDB-T:m-INPOIC:PC 71 BM based OSCs exhibit over 11% PCEs even with an active layer thickness over 300 nm. And the devices can retain over 95% of PCE after storage for 20 days. The outstanding tolerance to film thickness and outstanding stability of the as-cast devices make m-INPOIC a promising candidate NFA for large-scale solutionprocessable OSCs.

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Fluorination Triggered New Small Molecule Donor Materials for Efficient As‐Cast Organic Solar Cells

Cited by 26 publications

References 57 publications

Crucial Role of Fluorine in Fully Alkylated Ladder-Type Carbazole-Based Nonfullerene Organic Solar Cells

Crucial Role of Fluorine in Fully Alkylated Ladder-Type Carbazole-Based Nonfullerene Organic Solar Cells

Deciphering the Role of Fluorination: Morphological Manipulation Prompts Charge Separation and Reduces Carrier Recombination in All‐Small‐Molecule Photovoltaics

Molecular Orientation Unified Nonfullerene Acceptor Enabling 14% Efficiency As‐Cast Organic Solar Cells

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