Self-doping n-type polymer as a cathode interface layer enables efficient organic solar cells by increasing built-in electric field and boosting interface contact

Wang, Yufei; Liang, Zezhou; Li, Xiaoming; Qin, Jicheng; Ren, Meiling; Yang, Chunyan; Bao, Xichang; Tong, Junfeng; Li, Jianfeng

doi:10.1039/c9tc03506k

Cited by 96 publications

(45 citation statements)

References 59 publications

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“…Similarly, the IDIC‐4F‐based BHJ film displays Rq of 1.88 nm, which is obviously larger than that of the IDIC‐based counterpart (1.43 nm). As the AFM phase images indicate, relative to the IDIC‐based BHJ film, the IDIC‐4F‐based blend film presents a uniform yet more obvious nanofibrillar network (Figure b,d), which is advantageous for both interface contact and charge transport (Table ). As shown in the TEM images, the IDIC‐4F BHJ film displays clear phase separation with a scale of ≈25 nm and a clear donor/acceptor interpenetrating network, which facilitates exciton dissociation and charge transport.…”

Section: Resultsmentioning

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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Section: Resultsmentioning

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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“…The self‐doped polymers‐based electron transport layers have been broadly investigated to improve the ohmic contact between the BHJ layer and electrode in photovoltaic devices. Wang et al 183 synthesized PBTA‐FN and employed as a CIL in OSCs based on PBDB‐T‐2F:IT‐4F photoactive layer. The PCE dramatically increased from 11.02% to 12.18% with the PBTA‐FN interlayer.…”

Section: Cathode Interlayer Materialsmentioning

confidence: 99%

Recent progress in cathode interlayer materials for non‐fullerene organic solar cells

Ahmad

Zhou

Fan

et al. 2021

EcoMat

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Non‐fullerene acceptors are currently a hot research area in the development of organic solar cells (OSCs). At present, the‐state‐of‐the‐art power conversion efficiency (PCE) of non‐fullerene organic solar cells (NF‐OSCs) with single and multiple‐junction has surpassed 18% and 19%, respectively. The cathode interlayer (CIL) plays a significant role in the improvement of PCE and the stability of OSCs. Recently, a large number of CIL materials have been employed in OSCs. This review summarizes the recent progress of CIL materials and systematically describes their impact on the device efficiency and stability in single‐junction NF‐OSCs. Firstly, the functions, key requirements, and distinctive features of CILs when used in NF‐OSCs are summarized. Afterward, some big families of materials including metal oxides, metal salts/complexes, small molecules, polymers, composites/hybrids are presented as CIL for NF‐OSCs. Finally, the scale‐up techniques, conclusion, and future challenges regarding CIL in NF‐OSCs are elucidated.

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“…Due to the large planar structure of the electron-donating group benzo [1,2-b:4,5-b’] dithiophene (BDT), it has received extensive attention in constructing a D-A polymer of high performance PSCs [7,8,9,10,11,12,13,14,15,16]. Applying two-dimensional (2D)-conjugated BDT units (alkylthienyl- and alkylthio-thienyl-substituted BDT) and multifarious chemical moieties (para-alkylphenyl, metaalkoxylphenyl and 2-alkyl-3-fluorothienyl) play an important role in boosting the performance of the material and photovoltaic device, such as the adjustments of the absorption characteristic and energy levels, backbone conformation, charge transport performance, etc.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Photovoltaic Effect of Electron-Withdrawing Units for Low Band Gap Conjugated Polymers Bearing Bi(thienylenevinylene) Side Chains

Wang

et al. 2019

Polymers

Self Cite

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A novel (E)-5-(2-(5-alkylthiothiophen-2-yl)vinyl)thien-2-yl (TVT)-comprising benzo[1,2-b:4,5-b’]dithiophene (BDT) derivative (BDT-TVT) was designed and synthetized to compose two donor-acceptor (D-A) typed copolymers (PBDT-TVT-ID and PBDT-TVT-DTNT) with the electron-withdrawing unit isoindigo (ID) and naphtho[1,2-c:5,6-c′]bis[1,2,5]thiadiazole (NT), respectively. PBDT-TVT-ID and PBDT-TVT-DTNT showed good thermal stability (360 °C), an absorption spectrum from 300 nm to 760 nm and a relatively low lying energy level of Highest Occupied Molecular Orbital (EHOMO) (−5.36 to –5.45 eV), which could obtain a large open-circuit voltage (Voc) from photovoltaic devices with PBDT-TVT-ID or PBDT-TVT-DTNT. The photovoltaic devices with ITO/PFN/polymers: PC71BM/MoO3/Ag structure were assembled and exhibited a good photovoltaic performance with a power conversion efficiency (PCE) of 4.09% (PBDT-TVT-ID) and 5.44% (PBDT-TVT-DTNT), respectively. The best PCE of a PBDT-TVT-DTNT/PC71BM-based device mainly originated from its wider absorption, higher hole mobility and favorable photoactive layer morphology.

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Self-doping n-type polymer as a cathode interface layer enables efficient organic solar cells by increasing built-in electric field and boosting interface contact

Abstract: Self-doped polymer cathode interface materials for organic solar cells have been widely investigated to enhance the ohmic contact between the electrode and the photoactive layer.

Cited by 96 publications

References 59 publications

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

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

Recent progress in cathode interlayer materials for non‐fullerene organic solar cells

Synthesis and Photovoltaic Effect of Electron-Withdrawing Units for Low Band Gap Conjugated Polymers Bearing Bi(thienylenevinylene) Side Chains

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