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Effect of Thionation on the Performance of PNDIT2-Based Polymer Solar Cells
摘要： All-polymer solar cells have gained traction in recent years with solar cell performance of over 11% power conversion efficiency (PCE) recently demonstrated. The n-type polymer PNDIT2, also known as N2200 or P(NDI2OD-T2), has been extensively used for both photovoltaic as well as field-effect transistor applications. When paired with donor materials that have appropriately aligned energy-levels, PNDIT2 has exhibited device efficiencies over 10% PCE, and organic field effect transistors fabricated with PNDIT2 exhibit mobilities over 1 cm2/Vs. Thionation of the NDI moiety, which is the substitution of imide oxygen with sulfur atoms, has been shown to improve the field-effect transistor performance of NDI-based small molecules. Applying this strategy to PNDIT2, we explored the effect that thionation, in a 2S-trans configuration, has on the performance of all-polymer solar cells fabricated with the donor polymer PTB7-Th. Solar cells were fabricated with the original polymer, PNDIT2, as a reference, and an optimized efficiency of 4.85% was achieved. As samples with 100% conversion to 2S-trans configuration could not be produced due to synthetic limitations, batches with increasing ratios of 1S to 2S-trans thionation (15:85, 7:93, and 5:95) were studied. Devices with thionated PNDIT2 exhibited a systematic lowering of photovoltaic parameters with increasing thionation, resulting in device efficiencies of just 0.84%, 0.62%, and 0.42% PCE. The lower performance of the thionated blends is attributed to poor π-π stacking order in the thionated PNDIT2 phase, resulting in lower electron mobilities and finer phase separation. Evidence in support of this conclusion is provided by grazing incidence wide-angle X-ray scattering, transmission electron microscopy, photoluminescence quenching, transient photocurrent analysis, and SCLC measurements.
关键词： π-π stacking,PNDIT2,Thionation,All-polymer solar cells,Power conversion efficiency
更新于2025-10-22 19:40:53
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Perylene Diimide Based Conjugated Polymers for All Polymer Solar Cells
摘要： For recent decades, non-fullerene acceptors (NFAs) are undergoing rapid development and emerging as a hot area in the field of organic solar cells. Among the high performance nonfullerene acceptors, aromatic diimide based electron acceptors remain to be the highly promising systems. This review discusses the important progress of perylene diimide (PDI)-based polymers as nonfullerene acceptors (NFAs) in all polymer solar cells (all-PSCs) since 2014. The relationship between structure and property, matching aspects between donors and acceptors and device fabrications are unveiled from a synthetic chemist perspective.
关键词： nonfullerene acceptors (NFA),all-polymer solar cells (all-PSCs),energy levels,perylene diimide (PDI),PCE
更新于2025-09-23 15:21:01
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Ultranarrow Bandgap Naphthalenediimidea??Dialkylbifurana??Based Copolymers with Higha??Performance Organic Thina??Film Transistors and Alla??Polymer Solar Cells
摘要： A new polymer acceptor poly{(N,N′-bis(2-ethylhexyl)-1,4,5,8-naphthalenedicarboximide-2,6-diyl)-alt-5,5-(3,3′-didodecyl-2,2′-bifuran)} (NDI-BFR) made from naphthalenediimide (NDI) and furan-derived head-to-head-linked 3,3′-dialkyl-2,2′-bifuran (BFR) units is reported in this study. Compared to the benchmark polymer poly(naphthalenediimide-alt-bithiophene) (N2200), NDI-BFR exhibits a larger bathochromic shift of absorption maxima (842 nm) with a much higher absorption coefficient (7.2 × 104 m?1 cm?1), leading to an ultranarrow optical bandgap of 1.26 eV. Such properties ensure good harvesting of solar light from visible to the near-infrared region in solar cells. Density functional theory calculation reveals that the polymer acceptor NDI-BFR possesses a higher degree of backbone planarity versus the polymer N2200. The polymer NDI-BFR exhibits a decent electron mobility of 0.45 cm2 V?1 s?1 in organic thin-film transistors (OTFTs), and NDI-BFR-based all-polymer solar cells (all-PSCs) achieve a power conversion efficiency (PCE) of 4.39% with a very small energy loss of 0.45 eV by using the environmentally friendly solvent 1,2,4-trimethylbenzene. These results demonstrate that incorporating head-to-head-linked BFR units in the polymer backbone can lead to increased planarity of the polymer backbone, reduced optical bandgap, and improved light absorbing. The study offers useful guidelines for constructing n-type polymers with narrow optical bandgaps.
关键词： absorption coefficients,ultranarrow bandgap,all-polymer solar cells,polymer acceptors
更新于2025-09-23 15:21:01
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10.13% Efficiency Alla??Polymer Solar Cells Enabled by Improving the Optical Absorption of Polymer Acceptors
摘要： All-polymer solar cells (all-PSCs) are one of the most promising flexible and wearable energy generators due to their excellent morphology stability and mechanical robustness. However, it has been limited light absorption capacity for most polymer acceptors that hinders the improvement of power conversion efficiency (PCE) of all-PSCs. Herein, by simultaneously increasing the conjugation of the acceptor unit and enhancing the electron-donating ability of the donor unit, a novel narrow-bandgap polymer acceptor PF3-DTCO based on a A-D-A-structured acceptor unit ITIC16 and a carbon-oxygen (C-O)-bridged donor unit DTCO was developed. Extended conjugation of the acceptor units from IDIC16 to ITIC16 result in a red-shifted absorption spectrum and improved absorption coefficient without significant LUMO level reduction. Moreover, in addition to further broadening the absorption spectrum by the enhanced intramolecular charge transfer effect, the introduction of C-O-bridges into donor unit improves the absorption coefficient and electron-mobility, as well as optimizes the morphology and molecular order of active layers. As a result, the PF3-DTCO achieved a higher PCE of 10.13% with a higher short-circuit current density (Jsc) of 15.75 mA cm-2 in all-PSCs compared to its original polymer acceptor PF2-DTC (PCE=8.95% and Jsc=13.82 mA cm-2). Our work provides a promising method to construct high-performance polymer acceptors with excellent optical absorption for efficient all-PSCs.
关键词： optical absorption,all-polymer solar cells,polymer acceptor,carbon-oxygen-bridging,power conversion efficiency
更新于2025-09-23 15:19:57
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Effects of a Fluorinated Donor Polymer on the Morphology, Photophysics, and Performance of All-Polymer Solar Cells based on Naphthalene Diimide-Arylene Copolymer Acceptors
摘要： Naphthalene diimide (NDI)-biselenophene copolymer (PNDIBS) and NDI-selenophene copolymer (PNDIS) and the fluorinated donor polymer PM6 were used to investigate how a fluorinated polymer component affects the morphology and performance of all-polymer solar cells (all-PSCs). Although the PM6:PNDIBS blend system exhibits a high open-circuit voltage (Voc = 0.925 V) and desired low optical bandgap energy loss (Eloss = 0.475 eV), the overall power conversion efficiency (PCE) was 3.1%. In contrast, PM6:PNDIS blends combine a high Voc (0.967 V) with a high fill factor (FF = 0.70) to produce efficient all-PSCs with 9.1% PCE. Furthermore, the high performance PM6:PNDIS all-PSCs could be fabricated by various solution processing approaches and at active layer thickness as high as 300 nm without compromising photovoltaic efficiency. The divergent photovoltaic properties of PNDIS and PNDIBS when paired respectively with PM6 are shown to originate from the starkly different blend morphology and blend photophysics. Efficient PM6:PNDIS blend films were found to exhibit a vertical phase stratification along with lateral phase separation while the molecular packing had a predominant face-on orientation. Bulk lateral phase separation with both face-on and edge-on molecular orientations featured in the poor performing PM6:PNDIBS blend films. Enhanced charge photogeneration and suppressed geminate and bimolecular recombinations with 99% charge collection probability found in PM6:PNDIS blends strongly differ from the poor charge collection probability (66%) and high electron-hole pair recombination seen in PM6:PNDIBS. Our findings demonstrate that beyond the generally expected enhancement of Voc, a fluorinated polymer component in all-PSCs can also exert a positive or negative influence on photovoltaic performance via the blend morphology and blend photophysics.
关键词： Naphthalene Diimide-Arylene Copolymer,Fluorinated donor polymer,Vertical phase stratification,All-polymer solar cells,Thick-film active layer,Blend Morphology
更新于2025-09-23 15:19:57
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Quantification of Photophysical Processes in Alla??Polymer Bulk Heterojunction Solar Cells
摘要： Combined data of transient optical and electro-optical experiments reveals the efficiency-determining processes in all-polymer solar cells and allows precisely quantifying their yields. For the test system presented here, field-dependent charge separation is shown to limit the fill factor and thus the performance by comparing the experimentally-measured current-voltage characteristics to those reproduced by drift-diffusion simulations using the spectroscopically-determined kinetic parameters.
关键词： all-polymer solar cells,bulk heterojunction,non-fullerene acceptors,transient absorption,organic photovoltaics
更新于2025-09-23 15:19:57
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Mechanically Robust All-Polymer Solar Cells from Narrow Band Gap Acceptors with Hetero-Bridging Atoms
摘要： A series of polymer acceptors PF2-DTC, PF2-DTSi, and PF2-DTGe with identical molecular backbone but different central bridging atoms in tricyclic-fused donor units were developed. In all-PSCs, the PF2-DTSi-based blend film exhibited excellent mechanical robustness with an impressively high PCE of up to 10.77%. Moreover, the flexible solar cell based on this blend retained >90% of its initial PCE after bending and relaxing 1,200 times at a bending radius of ~4 mm.
关键词： Mechanical robustness,All-polymer solar cells,Narrow band gap acceptors,Power conversion efficiency,Hetero-bridging atoms
更新于2025-09-23 15:19:57
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Highly thermally stable all-polymer solar cells enabled by photo-crosslinkable bromine-functionalized polymer donors
摘要： Here, high performance polymers bearing photo-crosslinkable function are developed for all-PSCs to achieve both high efficiency and stability. Then, a series of novel -(D-A)a-(D-D1)b-type photo-crosslinkable bromine (Br)-functionalized polymer donors PBDT(T)FTAZ-BX were synthesized, in which typical benzodithiophene (BDT) derivative was as first component (D), thiophene-difluoro-benzotriazole (FTAZ) derivative was as second component (A), new simple BDT-based functionality appended Br-unit synthesized in this study was as third component (D1). The effects of Br-functionalized component on the photoelectric properties of the polymers were investigated. Moreover, UV-mediated photo-crosslinking effects on performance and thermal stability were thoroughly explored. All-PSCs based on these photo-crosslinkable polymers and N2200, but without photo-crosslinking, displayed a highest PCE of 7.21%, which was achieved by an optimized PBDT(T)FTAZ-B5-based device. As results, photo-crosslinked PBDT(T)FTAZ-B5 + UV5min-based devices afford extraordinarily excellent thermal stability, in which high retention rate of 91.8% of the maximum PCEavg and the intrinsic performance (PCEmax: 6.12%) are maintained even after 72 h 150 °C annealing. For comparison, reference PBDT(T)FTAZ-based devices only display PCEmax value of 5.13% and retain 84.2% of their maximum PCEavg under same aging. This contrasting result indicates that developing photo-crosslinkable Br-functionalized polymers is an effective strategy to further advance in both stability and efficiency of all-PSCs.
关键词： Bromine-functionalized,All-polymer solar cells,Thermal stability,Photo-crosslinkable
更新于2025-09-23 15:19:57
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Elucidating Roles of Polymer Donor Aggregation in All-Polymer and Non-Fullerene Small-Moleculea??Polymer Solar Cells
摘要： The aggregation behavior of polymers plays a crucial role in determining the optical, electrical, and morphological properties of donor-acceptor blends in both all-polymer solar cells (all-PSCs) and non-fullerene small molecule acceptor-polymer solar cells (NFSMA-PSCs). However, direct comparison of the impacts on two different systems has not been reported, although it is important to design universal polymer donors (PDs). Herein, three PDs with different side chains (P-EH, P-SEH and P-Si) are designed to study the PD aggregation effects on the blend morphology and device performance of both all-PSCs and NFSMA-PSCs. It is observed that the aggregation property of PDs is a critical factor in determining the optimal blend morphologies and ultimately the device performances in both the PSC systems. Furthermore, PD aggregation effects on device performance is significantly more impactful in all-PSCs than in NFSMA-PSCs. The P-Si PD exhibiting the strongest aggregation behavior in a processing solvent produces the most severe phase separation in the blend with a polymer acceptor, resulting in the lowest power conversion efficiency (PCE) of all-PSCs. In contrast, when P-Si is used in an NFSMA-PSC, a well-mixed blend morphology is observed, which results in the highest PCE of over 12%. These different roles dependent on PD aggregation mainly originate from the difference in molecular size of polymer acceptor and small molecule acceptor, which influences the entropic contribution to the formation of blend morphology. Our work provides a comprehensive understanding on the PD aggregation-blend morphology relationship in different all-PSC and NFSMA-PSC systems, which serves as an important guideline for the design of universal PDs for both all-PSCs and NFSMA-PSCs.
关键词： polymer solar cells,all-polymer solar cells,non-fullerene small molecule acceptor-polymer solar cells,polymer donor aggregation,blend morphology,power conversion efficiency
更新于2025-09-19 17:13:59
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Naphthalene Diimide-Based Terpolymers with Controlled Crystalline Properties for Producing High Electron Mobility and Optimal Blend Morphology in All-Polymer Solar Cells
摘要： We report a series of new n-type random copolymers (P(NDI2OD-Se-Th x) where x = 0, 0.5, 0.7, 0.8, 0.9, 1.0) consisting of naphthalene diimide (NDI), selenophene-2,2’-thiophene (Se-Th), and seleno[3,2-b]thiophene (SeTh) to demonstrate their use in producing efficient all-polymer solar cells (all-PSCs) and organic field-effect transistors (OFETs). To investigate the effect of polymer crystallinity on the performance of all-PSCs and OFETs, we tuned the composition of the Se-Th and SeTh moieties in the P(NDI2OD-Se-Th x) polymers, resulting in enhanced crystalline properties with higher Se-Th ratio. Thus, the OFET electron mobility was increased with higher Se-Th ratio, exhibiting the highest value of 1.38×10?1 cm2 V?1 s?1 with P(NDI2OD-Se-Th 1.0). However, the performance of all-PSCs based on PBDB-T:P(NDI2OD-Se-Th x) showed a non-linear trend relative to the Se-Th ratio and the performance was optimized with P(NDI2OD-Se-Th 0.8) exhibiting the highest power coversion efficiency of 8.30%. This is attributed to the stronger crystallization-driven phase separation in all-polymer blends for higher Se-Th ratio. At the optimal crystallinity of P(NDI2OD-Se-Th 0.8) in all-PSCs, the degree of phase separation, domain purity and the electron mobility were optimized, resulting in enhanced charge generation and transport. Our works describe structure-property-performance relationships to design effective n-type polymers in terms of crystalline and electrical properties suitable for both efficient OFETs and all-PSCs.
关键词： organic field-effect transistors,seleno[3,2-b]thiophene,polymer crystallinity,n-type random copolymers,selenophene-2,2’-thiophene,charge generation,all-polymer solar cells,charge transport,naphthalene diimide
更新于2025-09-19 17:13:59