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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Degradation Mechanism Identified for the Fullerene and Non-fullerene based Organic Solar Cells under Ambient Condition
摘要： Solution-processed organic solar cells (OSCs) have becoming a promising photovoltaic technology for a low-cost electricity generation. However, poor stability of OSCs is still a severe problem need to be understood and solved for future application. In this work, we conducted an air stability study for both fullerene and non-fullerene based OSCs. As a result, the degradation mechanism was found different for these two types of OSCs. The Urbach energy determined the EQE measurement indicates that the air-degradation in fullerene based OSCs is mainly ascribed to its increased energetic disorder. Differently, the photoluminescence (PL) measurement implied that the air-degradation in non-fullerene based OSCs mainly results from the degraded charge dissociation and energy transfer ability. Therefore, different stability improving strategy will be needed for fullerene and non-fullerene based OSCs in future.
关键词： non-fullerene,air stability,degradation mechanism,fullerene,organic solar cells
更新于2025-09-23 15:19:57
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Direct conjugation with a zero length linker of fullerene C <sub/>70</sub> to ZnO quantum dots for multicolor light-emitting diodes
摘要： Environmentally friendly metal oxide quantum dots (QDs) nanostructures has become attractive alternative materials for replacing QDs containing toxic elements of Cd and Pb. Although many attempts have been proposed for optoelectronic applications of hybrid metal oxide QDs with tailored opto-electronic properties, the fabrication of heterogeneous QD-fullerene hybrids as an emissive material has been little studied for optoelectronic devices. Herein, we report the preparation of ZnO-fullerene C70 (ZnO-C70) QDs by facile chemical reaction with zero length linker and demonstrate whitish light-emitting diodes by fullerene induced multicolor emission from ZnO-C70 QDs heterostructure. The electroluminescence (EL) is attributed to three new emission features in the visible region that originates from the electron transitions from three split lowest unoccupied molecular orbital levels of C70 molecules to the valence band of ZnO QDs. Compared with photoluminescence, the EL emissions were red-shifted by 50 - 130 meV due to the interaction between ZnO-C70 QDs in solid state. Energy levels of C70 were also suitably aligned to those of ZnO QDs with lower electron transfer barrier of 0.22 eV, which offers an advantageous route for electron transport. Consequently, the environmentally friendly ZnO-C70 QDs with extraordinary properties promise great potential for use as novel encapsulating materials in the field of opto-electronic applications adopting QDs.
关键词： Fullerene C70,Light emitting diodes,ZnO-fullerene C70 heterostructure,C60,Quantum dots,0D-0D heterostructures
更新于2025-09-23 15:19:57
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Higha??Performance Ternary Organic Solar Cells with Morphologya??Modulated Hole Transfer and Improved Ultraviolet Photostability
摘要： Ternary bulk-heterojunction (BHJ) strategy synergistically combining the merits of fullerene and non-fullerene acceptors has been regarded as a promising approach to enhance the power conversion efficiencies (PCEs) of organic solar cells (OSCs). Herein, the fullerene derivative ICBA as the morphology regulator is incorporated into non-fullerene based PBDB-T-2F:BTP-4Cl (PM6:BTP-4Cl) system to fabricate the high-performance ternary OSCs. The amorphous ICBA prefers to homogeneously distribute in the BTP-4Cl phase to form the well-mixed acceptor domains due to their better miscibility, which distinctly reduces the exciton decay loss driven by the unfavorable phase separation and enhances BHJ morphology stability of ternary blends. The appropriate addition of ICBA induces the efficient long-range F?rster resonance energy transfer to BTP-4Cl and facilitates the ultrafast hole transfer process from BTP-4Cl to PM6, thereby contributing to charge carrier generation in the actual devices. Ultimately, the optimal ternary OSCs not only yield the average PCE higher than 16.5% but also show the superior ultraviolet photostability relative to binary control devices owing to the increased harvesting of ultraviolet photons, boosted charge transfer, more balanced charge transport and more stable nano-structural morphology. Our results provide the new insights to enable the simultaneously improved device performance and tolerance to UV light in highly efficient ternary OSCs.
关键词： hole transfer,non-fullerene,ultraviolet photostability,ternary organic solar cells
更新于2025-09-23 15:19:57
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Simultaneous improvement of three parameters using binary processing solvent approach in as-cast non-fullerene solar cells
摘要： As-cast polymer solar cells without any additive and pre- or post-treatment principally are of high compatibility with mass production technologies, whose efficiencies are typically promoted by new donor and acceptor materials. In this work, a binary solvent approach using chloroform (CF) of low boiling point as good solvent for both polymer donor PTQ10 and non-fullerene acceptor IT-4Cl and mesitylene (MES) of relatively high boiling point as a semi-orthogonal co-solvent due to weaker solubility to the acceptor is explored. Due to the selective orthogonality of MES to the IT-4Cl acceptor, an optimized morphology has been realized for the as-cast device based on the PTQ10:IT-4Cl blend, which leads to a simultaneous improvement in the open-circuit voltage, short-circuit current, and fill factor, finally achieving a high as-cast efficiency of over 13%. Furthermore, the as-cast devices fabricated with the binary solvent can exhibit good air stability and great accessibility in large area cells. Our findings provide an alternative guideline for the optimization of the as-cast polymer solar cells.
关键词： polymer solar cells,morphology optimization,non-fullerene acceptor,binary solvent,as-cast
更新于2025-09-23 15:19:57
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Efficient Organic Solar Cells Based on Non-Fullerene Acceptors with Two Planar Thiophene Fused Perylene Diimide Units
摘要： We designed and synthesized two non-fullerene acceptors (CDT-TFP and C8X-TFP), which comprise a central 4H-cyclopenta[2,1-b:3,4-b’]dithiophene (CDT) as the bridge and two thiophene-fused perylene diimide (TFP) units. The bulky side chains, such as the 4-hexylphenyl side chains, on the CDT bridge can effectively prevent the acceptor molecules from forming large aggregates and the π-π stacking of the terminal planar TFP units can form effective electron transport pathways when blending with the donor polymers. These non-fullerene acceptors are used to fabricate organic solar cells (OSCs) by blending with regioregular middle bandgap polymer reg-PThE. The as-cast devices based on reg-PThE:CDT-TFP show the best PCE of 8.36% with a Voc of 1.10 V, Jsc of 12.43 mA cm-2 and FF of 61.4%; whereas, the analogue PDI dimers (CDT-PDI) that comprising two PDI units bridged with a CDT unit, show only a 2.59% PCE with a Voc of 0.92 V, Jsc of 6.82 mA cm-2 and FF of 41.5%. Our results have demonstrated that non-fullerene acceptors comprising planar PDI units can achieve excellent photovoltaic performance and provide meaningful guidelines for the design of PDI based non-fullerene electron acceptors for efficient OSCs.
关键词： regioregular donor polymer,perylene diimide,organic solar cells,non-fullerene electron acceptors,planar
更新于2025-09-23 15:19:57
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Barrier-Free Charge Separation Enabled by Electronic Polarization in High-Efficiency Non-Fullerene Organic Solar Cells
摘要： The separation of charge-transfer (CT) states into free charges at the donor/acceptor (D/A) interfaces plays a central role for organic solar cells (OSCs). Because of strong Coulomb attraction, the separation mechanisms are elusive, particularly for the high-efficiency non-fullerene (NF) OSCs with low exciton-dissociation driving forces. Here, we demonstrate that the Coulomb barriers can be substantially overcome by electronic polarization for OSCs based on a series of A-D-A acceptors (ITIC, IT-4F, and Y6). In contrast to fullerene-based D/A heterojunctions, the polarization energies for both donor holes and acceptor electrons are remarkably increased from the interfaces to pure regions in the NF heterojunctions owing to strong stabilization on electrons but destabilization on holes by electrostatic interactions in the A-D-A acceptors. Especially, upon incorporating fluorine substituents and electron-poor cores to ITIC, the increased polarization energies can completely compensate the Coulomb attraction in the IT-4F and Y6 based Heterojunctions, leading to barrierless charge separation.
关键词： electrostatic interaction,induction effect,charge generation,organic photovoltaics,non-fullerene acceptors
更新于2025-09-23 15:19:57
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Chlorinated Fullerene Dimers for Interfacial Engineering Toward Stable Planar Perovskite Solar Cells with 22.3% Efficiency
摘要： A major limit for planar perovskite solar cells is the trap-mediated hysteresis and instability, due to the defective metal oxide interface with the perovskite layer. Passivation engineering with fullerenes has been identified as an effective approach to modify this interface. The rational design of fullerene molecules with exceptional electrical properties and versatile chemical moieties for targeted defect passivation is therefore highly demanded. In this work, novel fulleropyrrolidine (NMBF-X, X=H or Cl) monomers and dimers are synthesized and incorporated between metal oxides (i.e. TiO2, SnO2) and perovskites (i.e. MAPbI3 and (FAPbI3)x(MAPbBr3)1-x). The fullerene dimers provide superior stability and efficiency improvements compared to the corresponding monomers, with chlorinated fullerene dimers being most effective at coordinating with both metal oxides and perovskite via the chlorine terminals. The non-encapsulated planar device delivers a maximum power conversion efficiency of 22.3% without any hysteresis, while maintaining over 98% of initial efficiency after ambient storage for 1000 h, and exhibiting an order of magnitude improvement of the T80 lifetime.
关键词： stability,perovskite solar cells,fullerene dimers,interfacial engineering
更新于2025-09-23 15:19:57
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Constructing Higha??Performance Organic Photovoltaics via Emerging Nona??Fullerene Acceptors and Tandema??Junction Structure
摘要： In consideration of the unique advantages of new non-fullerene acceptors and the tandem-junction structure, organic photovoltaics (OPVs) based on them are very promising. Studies related to this emerging area began in 2016 with achieved power conversion efficiencies (PCEs) of 8–10%, which have now been boosted to 17%. In this essay, the construction of high-performance OPVs is discussed, with a focus on combining the advantages of new non-fullerene acceptors and the tandem-junction structure. In order to achieve higher PCEs, methods to enable high short-circuit current density, open-circuit voltage, and fill factor are discussed. In addition, the stability and reproducibility of high-efficiency OPVs are also addressed. Herein, it is forecast that the new non-fullerene acceptors-based tandem-junction OPVs will become the next big wave in the field and achieve high PCEs over 20% in the near future. Some promising research directions on this emerging hot topic are proposed which may further push the field into the 25% high efficiency era and considerably advance the technology beyond laboratory research.
关键词： non-fullerene acceptors,organic solar cells,organic photovoltaics,tandem solar cells
更新于2025-09-23 15:19:57
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Tuning the optoelectronic properties of Benzo Thiophene (BT-CIC) based Non-Fullerene Acceptor Organic Solar Cell
摘要： Organic solar cells have become a center of attention in the field of research and technology due to its remarkable features. In current research work, we designed Benzo Thiophene (BT-CIC) based non-fullerene acceptor organic solar cell having A-D-A novel structure. The designed structures D1-D4 were derived from BT-CIC (non-fullerene acceptor) by replacing 2-(5,6-dichloro-2-methylene-3-oxo-2,3-dihydro-1H-inden-1-ylidene)acetonitrile of reference molecule R with different electron withdrawing end-capper acceptor moieties. The e?ect of end acceptor groups on absorption, energy level, charge transport, morphology, and photovoltaic properties of the designed molecules (D1-D4) were investigated by TD-DFT B3LYP/6-31G basic level of theory and compared with reference molecule R. Among all novel structures, D3 exhibited maximum absorption (λmax) of 701.7nm and 755.2 nm in gaseous state and chloroform respectively. The red shift in D3 was due presence of strong electron withdrawing acceptor moiety and more extended conjugation as compared to other structures. D3 also displayed lowest values of energy band gap (1.97 eV), λe (0.0063 eV) and λh (0.0099 eV) and which signify its ease electron mobility. Lowest value of binding energy 1.20 eV of D3 suggested that this molecule could be easily dissociated into charge carriers TDM results revealed that easy exciton dissociation occurred in D3. Overall, designed structure D3 was found to be more effective and efficient acceptor molecule for SMOSCs. The findings provide novel information for the development of non-fullerene acceptors for OPVs.
关键词： theoretical studies,opto-electronic properties,benzothiophene,organic solar cells,Non-Fullerene Acceptor
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