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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Improvement of External Quantum Efficiency of C <sub/>60</sub> /ZnPc Organic Photovoltaic Cells by Polymerization between C <sub/>60</sub> molecules
摘要： We have found that the external quantum efficiency of C60/ZnPc hetero-junction organic photovoltaics are improved by photo-induced polymerization between C60 molecules.
关键词： Fullerene,Organic Solar Cell,Energy Harvesting,Polymerization
更新于2025-09-16 10:30:52
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Efficient non-fullerene organic solar cells based on thickness-insensitive conjugated small molecule cathode interface
摘要： Interfacial engineering plays an essential role in the enhancement of device performance of organic solar cells (OSCs). Plentiful dopant-free electron- transporting materials have been e?ectively applied to modify ZnO in the inverted OSCs. However, these materials usually work with strict thickness, which observably limits their application in large area device fabrication. In this manuscript, an industrial small-molecule PyM with simply chemical structure solved in methyl alcohol was applied to modify ZnO in non-fullerene OSCs. PyM has good solubility in both methyl alcohol and chlorobenzene. Therefore, there is only a thin PyM layer left and distributed on the ZnO surface after coating the active layer. Meanwhile, a small amount PyM may be blended with the active layer near ZnO layer. The intense interaction between ZnO and PyM layer as well as the potential n-doping between PyM and the electron acceptor could modify the work function of ZnO and reduce the charge carrier recombination. Correspondingly, the inverted PBDB-T:ITIC OSCs with ZnO/PyM serving as electron transport layers achieve device power conversion e?ciency (PCE) of 10.9% and 10.0% with 10 nm and 105 nm thick PyM ?lm, respectively. The device performance is insensitive to the thickness of PyM. This phenomenon indicates that the PyM can be employed in roll-to-roll techniques to fabricate large-area devices at low cost. Similar results also emerged in PBDB-T:IT-M system, and the PCE was improved from 10.4% to 11.5% for ZnO and ZnO/PyM (~10 nm)-based devices.
关键词： Cathode interface,Organic solar cells,Hydrophobic property,Non-fullerene,Hydrogen bond,Thickness-insensitive
更新于2025-09-16 10:30:52
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5H-Fluoreno [3,2- b:6,7- b’] Dithiophene Based Non-fullerene Small Molecular Acceptors for Polymer Solar Cell Application
摘要： Two novel non-fullerene small molecule acceptors were prepared with the conjugated backbone of 5H- fluoreno[3, 2- b:6, 7- b’] dithiophene carrying the electron deficient unit of dicyanomethylene indanone (DICTFDT) and rhodanine (TFDTBR), respectively. The two acceptors exhibited excellent thermal stability and strong absorption in the visible region. The LUMO level is estimated to be at -3.89 eV for DICTFDT and -3.77 eV for TFDTBR. When utilized as the acceptor in bulk heterojunction polymer solar cells with the polymer donor of PBT7-Th, the optimized maximum power conversion efficiency of 5.12% and 3.95% was obtained for the device with DICTFDT and TFDTBR, respectively. The research demonstrates that 5H- fluoreno[3, 2- b:6, 7- b’] dithiophene can be an appealing candidate for constructing small molecular electron acceptor towards efficient polymer:non-fullerene bulk heterojunction solar cells.
关键词： polymer solar cells,non-fullerene acceptor,bulk heterojunction
更新于2025-09-16 10:30:52
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Fluorinated fulleropyrrolidine as universal electron transport material for organic-inorganic and all-inorganic perovskite solar cells
摘要： [6,6]-Phenyl-C61-butyric acid methylester (PC61BM) has been widely used as electron transport material (ETM) for both organic-inorganic hybrid and all inorganic perovskite solar cells (PeSCs) with inverted structure. However, PC61BM still remains to be improved due to its low electrical conductivity and inferior passivation effect towards perovskite. In this work, we synthesize two perfluorophenyl-substituted fulleropyrrolidines, 2-(perfluorophenyl)-5-phenyl-C60-fulleropyrrolidine (FP-i) and 2,5-bis-(perfluorophenyl)-C60-fulleropyrrolidine (FP-ii) via a modified 1,3-dipolar cycloaddition reaction. FP-i and FP-ii are introduced into inverted PeSCs based on organic-inorganic hybrid and all inorganic perovskites (CH3NH3PbCl3-xIx and CsPbI2Br) as ETMs. The PeSCs based on FP-i and FP-ii display good photovoltaic performance and device stability, which are superior or comparable to those with PC61BM. The mechanism studies reveal that FP-i and FP-ii possess higher electrical conductivity, more significant passivation capacity and enhanced hydrophobicity but slightly lower low unoccupied molecular orbital (LUMO) levels. These results suggest that FP-i and FP-ii are universal ETMs for both organic-inorganic hybrid and all inorganic PeSCs, which are better or comparable to conventional ETM of PC61BM.
关键词： Inverted perovskite solar cell,Fullerene derivative,Passivation effect,Device stability,Electron transporting layer
更新于2025-09-16 10:30:52
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A “Positive Incentive” Approach to Enhance Operational Stability of Quantum Dot based Light-Emitting Diode
摘要： Balanced charge injection promises high efficiency of quantum dot based light-emitting diodes (QD-LEDs). Most widely used approach to realize charge injection balance is impeding the injection rate of the dominant charge carrier with energetic barriers. However, these approaches often accompany unwanted outcomes (e.g., the increase in operation voltage) that sacrifice the operation stability of devices. Herein, a “positive incentive” approach is proposed to enhance the efficiency and the operational stability of QD-LEDs. Specifically, the supply of hole, an inferior carrier than its counterpart, is facilitated by adopting a thin fullerene (C60) interlayer at the interface between hole injection layer (MoOX) and hole transport layer (CBP). The C60 interlayer boosts the hole current by eliminating the universal energy barrier, lowers the operation voltage of QD-LEDs, and enhances the charge balance in the QD emissive layer within working device. Consequently, QD-LEDs benefitting from the adoption of C60 interlayer exhibit significantly enhanced device efficiency and operation stability. Grounded on the quantitative assessment of the charge injection imbalance within the QD emissive layer, the impact of electrical parameters of QD-LEDs to their optoelectronic performance and operational stability is also discussed.
关键词： hole injection barrier,operational stability,fullerene,quantum dot based light-emitting diodes,charge injection balance
更新于2025-09-16 10:30:52
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The Crucial Role of Fluorine in Fully Alkylated Ladder Type Carbazole Based Non-fullerene Organic Solar Cells
摘要： 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 1,1‐dicyanomethylene‐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.
关键词： fluorine effect,carbazole,fully alkylated side chains,organic solar cells,non‐fullerene acceptors
更新于2025-09-16 10:30:52
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Efficient and Mechanically Robust Ultraflexible Organic Solar Cells Based on Mixed Acceptors
摘要： A simple strategy to simultaneously improve power conversion efficiency (PCE) and mechanical stability of ultra?exible organic solar cells is reported. By using a fullerene/non-fullerene mixed acceptor, 3-mm-thick ultra?exible organic solar cells achieve a PCE of 13% (a certi?ed value of 12.3%) with 97% PCE retention after 1,000 bending cycles and 89% PCE retention after 1,000 compression-stretching cycles.
关键词： mixed acceptors,fullerene,mechanical stability,non-fullerene,ultra?exible organic solar cells,power conversion efficiency
更新于2025-09-12 10:27:22
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Cyclopentadithiophene cored A-π-D-π-A non-fullerene electron acceptor in ternary polymer solar cells to extend the light absorption up to 900?nm
摘要： Conjugated small molecular non-fullerene electron acceptors (NFA) are considered as one of the critical materials for achieving high performance and low cost of polymer solar cells, and received much attention in the last few years. However, most of the NFAs are based on large fused π-aromatic core, which requires complicate synthesis efforts. In addition, the relatively weak light absorption limited to 800 nm of most the NAFs limits the energy harvesting capability of the solar cells. In this paper, we report an A-π-D-π-A type molecule cored with a cyclopentadithiophene unit, which can be easily synthesized in two steps from commercially available starting materials. This compound shows a broad absorption up to 900 nm in thin solid film, which is ascribed to the relatively high highest occupied molecular orbital (HOMO) energy level as confirmed by cyclic voltammery and theoratical calculation. Application of the compound in polymer solar cells was also investigated both in binary and in ternary systems. The optimized power conversion efficiency (PCE) in binary solar cell with PTB7-Th as donor is 5.76% with an open circuit voltage (VOC) of 0.838 V, a short circuit current (JSC) of 14.81 mA/cm2 and a fill factor (FF) of 46.4%. In the ternary solar cells which includes a second acceptor, PC71BM, the highest PCE achieved is 9.39% with a VOC of 0.803 V, a JSC of 19.01 mA/cm2, a FF of 61.6%, which is over 20% enhancement compared to the PTB7-Th:PC71BM system (PCE of 7.58%). This work develops a simple small molecule non-fullerene acceptor which can largely enhance the photo response in near infrared region to improve the performance of fullerene based organic solar cell.
关键词： Light absorption,Non-fullerene electron acceptor,Cyclopentadithiophene,Ternary systems,Polymer solar cells
更新于2025-09-12 10:27:22
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Wide-Band-Gap Phthalimide-Based D-π-A Polymers for Nonfullerene Organic Solar Cells: The Effect of Conjugated π-Bridge from Thiophene to Thieno[3,2- <i>b</i> ]thiophene
摘要： Conjugated polymers with D-π-A backbone structures have been intensively investigated and have largely promoted the rapid progress of organic solar cells (OSCs). However, as one of the simplest electron-accepting (A) units, phthalimide (PhI), only attracts less attention to construct promising D-π-A photovoltaic polymers in OSC community. Thus the correlations between the chemical structure-optoelectronic properties-photovoltaic performance need to be systematically investigated. Here, we combined the PhI moiety with the electron-donating (D) unit benzodithiophene (BDT) to synthesize two D-π-A copolymers PE80 and PE81, where the π-bridge corresponds to the thiophene (T) and thieno[3,2-b]thiophene (TT) respectively. When blended with a low bandgap (Eg=1.33 eV) non-fullerene acceptor Y6, PE81 achieved a power conversion efficiency (PCE) of 10.21% with an open circuit voltages (VOC) of 0.90 V, which are much higher than those of PE80:Y6 device (PCE = 4.11% and VOC = 0.88 V). Our results indicate that PhI is also a promising electron-deficient unit to construct photovoltaic polymers and using TT π-bridge is simple strategy to improve the photovoltaic performance of D-π-A polymers.
关键词： non-fullerene organic solar cells,D-π-A backbone,Conjugated polymers,thieno[3,2-b]thiophene,phthalimide
更新于2025-09-12 10:27:22
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Scalable fabrication of organic solar cells based on non-fullerene acceptors
摘要： Organic solar cells have recently experienced a substantial leap in power conversion efficiency, in part driven by formulations with new non-fullerene acceptors. This has brought the technology past the psychologically important mark of 15 % efficiency for unscaled laboratory devices, and the results are stimulating another burst of research activity. Whether this will propel the technology into a viable commercial contender has yet to be determined, but to realize the potential of organic solar cells for utility scale application, fabrication using scalable processing techniques has to be demonstrated - otherwise, the passing of the 15 % mark will eventually leave no more lasting impact than what the passing of the 10 % mark did. Thus, addressing the scaling lag between the 15 % cell efficiencies of lab-scale devices on rigid glass substrates fabricated using non-scalable techniques and the 7 % efficiencies of scalably fabricated devices on flexible substrates is key. Here, we discuss the concept of scalability and give an account of the literature on non-fullerene acceptor devices fabricated with scalable methods and materials. On the basis of this, we identify three crucial focus points for overcoming the lab-to-fab challenge: i) dual temperature control, i.e. simultaneous control of the ink and substrate temperatures during deposition, ii) systematic in situ morphology studies of active layer inks with new, green solvent formulations during continuous deposition, and iii) development of protocols for continuous solution processing of smooth, transparent interfacial layers with efficient charge transfer to the active layer. Combining these efforts and in general accompanying such studies with stability analyses and fabrication of large-area, scalably processed devices are believed to accelerate the relevance of organic solar cells for large-scale energy supply.
关键词： roll-to-roll processing,organic solar cells,non-fullerene acceptors,power conversion efficiency,scalable fabrication
更新于2025-09-12 10:27:22