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Influence of the intramolecular donor-acceptor distance on the performance of double-cable polymers
摘要： A series of double-cable polymers PFT-C4-PDI, PFT-C6-PDI and PFT-C8-PDI, composed of the poly(fluorene-alt-thiophene) (PFT) backbone, the perylene diimide (PDI) pendants and the length-various (four-, six- and eight-carbon) covalent alkoxy linkers, were presented. The backbone polymer chain created the hole-transporting channel and the inner-chain aggregation of PDI units created the electron-transporting channel, but the aggregation became weaker along with the longer linker, as proven by the UV-Vis absorption and fluorescence quenching. The polymers were non-conducting, but functioned as efficient compatibilizers. The doping of the polymers induced the formation of the bi-continuous networks inside P3HT:PCBM blends, facilitated photo-generated exciton dissociation and charge transporting. PFT-C4-PDI more efficiently increased the absorption coefficient and the charge-carrier mobility of the P3HT:PCBM film. The power conversation efficiency (PCE) of the P3HT:PCBM bulk-heterojunction solar cells with 3 wt% PFT-C4-PDI, PFT-C6-PDI and PFT-C8-PDI doping were improved by 16.9%, 9.2% and 8.0%, respectively, relative to the non-doped reference device.
关键词： Structure-property relationships,Energy transfer,Double-cable polymer,Polymer solar cells,Bi-continuous networks
更新于2025-09-23 15:23:52
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Self-assembled bulk heterojunctions from integral molecules with nonconjugately linked donor and acceptor units for photovoltaic applications
摘要： The bi-continuous interpenetrating network of donor/acceptor with suitable phase-separated domain size is crucial for highly efficient organic bulk heterojunction solar cells considering that it guarantees effective exciton dissociation and smooth charge transport. For traditional binary blend bulk heterojunction, the photoactive layer is a simple physical mixture of donor and acceptor, the size of phase separation is primarily determined by the aggregation characteristics of the donor and acceptor respectively, it is hard to control and stabilize. To solve this problem, a kind of donor-acceptor integral molecule with donor units and acceptor units linked by non-conjugated flexible linking units has been proposed. The energy levels and the absorption spectra of the integral molecules can be easily tailed by tuning the donor and the acceptor units. Furthermore, the integral molecules can form a microphase separated bulk heterojunction of donor phase and acceptor phase through a self-assembly process of the molecule, which is governed by the flexible linking unit, responsible for connecting the donor and acceptor units. Since the donor and acceptor units of the integral molecules are connected by the non-conjugated units, the scale of aggregation and the morphology stability could be easily controlled. In this review, we first introduce the unique characteristics of the three typical donor-acceptor integral molecules and then highlight their current developments. For each donor-acceptor molecule, we attempt to give a detailed summarization on their design and synthesis, and an in-depth understanding on the basic mechanism of molecular self-assembly and the performance comparison of SMSCs. In the end, the prospect and potential improvements of donor-acceptor integral molecule are addressed, and we believe that emerging donor-acceptor molecule provide great opportunities for efficient and stable organic solar cells.
关键词： double-cable polymer,self-assembly,donor-acceptor integral molecule,donor-acceptor small molecule,single material organic solar cell,block copolymer
更新于2025-09-19 17:13:59
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Effect of Electron-Acceptor Content on the Efficiency of Regioregular Double-Cable Thiophene Copolymers in Single-Material Organic Solar Cells
摘要： Three regioregular thiophenic copolymers, characterized by a bromine atom or a C60-fullerene group at different molar ratios at the end of a decamethylenic plastifying side chain, have been successfully synthesized using a straightforward postpolymerization functionalization procedure based on a Grignard coupling reaction. Owing to their good solubility in common organic solvents, the products were fully characterized using chromatographic, spectroscopic, thermal, and morphological techniques and used as single materials in the photoactive layers of organic solar cells. The photoconversion efficiencies obtained with copolymers were compared with those of a reference cell prepared using a physical blend of the precursor homopolymer and [6,6]-phenyl-C61-butyric acid methyl ester. The best results were obtained with COP2, the copolymer with a 21% molar content of C60-functionalized side chains. The use of the double-cable polymer made possible an enhanced control on the nanomorphology of the active blend, thus reducing phase-segregation phenomena as well as the macroscale separation between the electron-acceptor and -donor components, yielding a power conversion efficiency higher than that of the reference cell (4.05 vs 3.68%). Moreover, the presence of the halogen group was exploited for the photo-cross-linking of the active layer immediately after the thermal annealing procedure. The cross-linked samples showed an increased stability over time, leading to good efficiencies even after 120 h of accelerated aging: this was a key feature for the widespread practical applicability of the prepared devices.
关键词： photo-cross-linking,C60-fullerene,double-cable polymer,thermal annealing,regioregular thiophenic copolymers,Grignard coupling reaction,organic solar cells,photoconversion efficiencies
更新于2025-09-11 14:15:04