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COMPARISON OF PERFORMANCES OF ORGANIC PHOTOVOLTAIC CELLS USING SubPc AS CENTRAL AMBIPOLAR LAYER IN TERNARY STRUCTURES AND AS ELECTRON ACCEPTOR IN BINARY STRUCTURES
摘要： We compare the performances of organic photovoltaic cells (OPVCs) based on binary and ternary planar heterojunctions. The organic active layers are pentathiophene (5T), subphthalocyanine (SubPc) and fullerene (C60). SubPc being an ambipolar material we used it either as electron acceptor in binary OPVCs or as central layer in ternary cells in order to increase the efficiency of OPVCs using 5T as electron donor. So, the different OPVC configurations were 5T/C60, 5T/SubPc and 5T/SubPc/C60. The effect of the different organic layer thicknesses on the device performances was studied. In order to understand the behavior of the different OPVC configurations, we proceeded with a morphological study. The influence of the high roughness of the 5T layer on the OPVCs performances is discussed. The best OPVCs performances are obtained with the binary structure 5T/SubPc. Its maximum efficiency corresponds to an increase of 50% compared to the OPVC based on the couple 5T/C60. External Quantum Efficiency measurements show that both layers participate to the current generation. The efficiency increase is mainly due to the increase of the open circuit voltage (Voc). In the case of ternary OPVCs, Voc is limited by the band structure of 5T and C60, moreover, the efficiency is also limited by the poor charge collection efficiency of the ternary structure and the series resistance of the three stacked organic layers.
关键词： Organic photovoltaic cells,ternary structures,pentathiophene,subphthalocyanine,binary structures
更新于2025-09-19 17:13:59
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The Role of Mineral Acid Doping of PEDOT:PSS and Its Application in Organic Photovoltaics
摘要： Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is one of the most successful conducting polymers in terms of commercialization. A method to readily obtain highly conductive and transparent PEDOT:PSS films is urgently needed. A simple method is introduced to enhance the conductivity of such films dramatically. By adding a series of mineral acids into the PEDOT:PSS aqueous solution directly, the conductivity is enhanced by 3–4 orders of magnitude. Mechanistic study reveals that the conductivity enhancement is dependent on boiling point, pKa value, softness parameter, and oxidability of the dopant acid. Specifically, acids with high boiling point, low pKa, and low softness parameter are able to induce phase separation between PEDOT and PSS, leading to secondary doping. If the dopant acid exhibits strong oxidability, the conductivity can also be enhanced via primary doping. H2SO4-doped PEDOT:PSS films exhibit the highest conductivity of 2244 S cm?1. These films are employed as the transparent electrodes of poly(3-hexylthiophene-2,5-diyl) (P3HT)-based organic photovoltaic cells, and the power conversation efficiency reaches 3.13%. These results suggest direct acid doping of PEDOT:PSS solution is a facile approach to obtain highly flexible transparent electrodes.
关键词： transparent flexible electrodes,PEDOT:PSS doping,organic photovoltaic cells
更新于2025-09-16 10:30:52
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Nontoxic pyrite iron sulfide nanocrystals as second electron acceptor in PTB7:PC <sub/>71</sub> BM-based organic photovoltaic cells
摘要： Herein, we report the synthesis of nontoxic pyrite iron sulfide (FeS2) nanocrystals (NCs) using a two-pot method. Moreover, we study the influence of these NCs incorporated into the PTB7:PC71BM active layer of bulk-heterojunction ternary organic photovoltaic (OPV) cells. The OPV devices are fabricated with the direct configuration glass/ITO/PEDOT:PSS/PTB7:PC71BM:FeS2/PFN/FM. The Field’s metal (FM) is a eutectic alloy composed of 32.5% Bi, 51% In and 16.5% Sn by weight that melts at 62 °C. It is deposited on the active layer/PFN under atmospheric conditions. Ternary active layers are prepared by adding small amounts of the semiconducting FeS2 NCs at different weight ratios of 0.0, 0.25, 0.5, and 1.0 wt % with respect to the electron donor PTB7. With respect to the reference device (without FeS2), a 21% increase in the power conversion efficiency (PCE) is observed for OPVs with 0.5 wt % FeS2, such that the PCE of the OPVs is enhanced from 5.69 to 6.47%. According to the Kruskal–Wallis and Mann–Whitney statistical tests, all OPV devices follow the same trend.
关键词： iron disulfide,nanoparticles,pyrite,organic photovoltaic cells (OPVs),PTB7
更新于2025-09-16 10:30:52
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New dielectric/metal/dielectric electrode for organic photovoltaic cells using Cu:Al alloy as metal
摘要： Given the rapidly increasing demand for flexible and inexpensive optoelectronic devices, it is necessary to find a substitute for ITO (Indium Tin Oxide). Among the considered alternatives, we have chosen in the present work Dielectric/Metal/Dielectric (D/M/D) trilayer structures deposited under vacuum. In these D/M/D structures, when Ag is the metal, highly performing and stable Transparent Conductive Electrodes (TCEs) are obtained. When Ag is replaced by Cu, which is far less expensive, results are not similar due to the tendency of Cu to diffuse into the transition metal oxides. Therefore we improve the stability of the new TCEs by using the Cu alloy Cu:Ag in ZnS/M/WO3 structures. The best results were obtained when M = Cu:Ag (16 nm)/Ag (1 nm). Flexible and quite stable TCEs were obtained. These new TCEs are conductive and transparent with a figure of merit of 6.5 x 10-3?-1 and a quite small Root Mean Squared Roughnessis (RMS = 1.1 nm). Therefore, they were introduced as anode in organic photovoltaic cells (OPVs). In the same time, ZnS/Ag/TiO2 TCE were probed. These ZnS/Ag/TiO2 structures were transparent and conductive with optical and electrical performances similar to those of ITO, but, when used as anode, the OPVs performances were limited by the presence of Ag at the surface of the structures. In the other hand, the results obtained with ZnS/M/WO3 structures were very promising with an open circuit voltage, Voc, and a short circuit current, Jsc, whose values are slightly higher than those obtained with ITO. Nevertheless the fill factor FF is sensibly smaller, which is attributed to the presence of some Cu at the surface of the electrode.
关键词： Cu:Ag alloy,Transparent conductive electrode,organic photovoltaic cells,dielectric-metal-dielectric structures,Indium free electrode
更新于2025-09-16 10:30:52
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New organic molecular based on Bis-Dipolar Diphenylamino-EndcappedOligo Aryl Fluorene Application for organic solar cells
摘要： In this work, we report on the structural, optical and electronic properties of a series of D-π-A-π-D type bis-dipolar Diphenylamino-Endcappedoligoarylfluorenes, (OF(2)Ar-NPh(2)). These molecules are studied by means of quantum chemical calculations based on density functional theory (DFT) using B3LYP functional with 6-31G(d,p) for all atoms and all states (ground and excited ). The study of the geometrical parameters, ground state (p, n) showed that the structures of these molecules are planar. As a result, the electronic properties HOMOs, LUMOs, energy gaps, were determined from the fully optimized structures. The absorption of these molecules were calculated using (TD-DFT)-B3LYP/631G (d,p) method. This fundamental information is a valuable data in designing and making promising materials for optoelectronic applications.
关键词： Optoelectronic applications,DFT,Organic,Photovoltaic cells
更新于2025-09-12 10:27:22
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High Open‐Circuit Voltage Organic Photovoltaics Fabricated Using an Alkylidene Fluorene Derivative as a Non‐fullerene Acceptor
摘要： Alkylidene ?uorene-based molecular acceptors, AF-T-INCN and AF-T8-INCN, are synthesized for use in non-fullerene organic photovoltaics. Both AF-T-INCN and AF-T8-INCN exhibited absorption region from 400 to 700 nm in their neat ?lm states. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels were found to be ?5.79/?3.80 eV for AF-T-INCN and ? 5.82/?3.79 eV for AT-T8-INCN, respectively. The organic solar cell devices fabricated with AF-T-INCN exhibited relatively low device performances with an open-circuit voltage (VOC) of 0.25 V, a short-circuit current density (JSC) 0.47 mA/cm2, a ?ll factor (FF) 29%, and power conversion ef?ciency (PCE) 0.03%, because of its strong aggregation in the blending condition. In contrast, AF-T8-INCN exhibited increased solubility and improved device performances with a high VOC of 1.24 V, a JSC 2.18 mA/cm2, a FF 28%, and PCE 0.76%.
关键词： Organic photovoltaic cells,Non-fullerene acceptor,Alkylidene ?uorene
更新于2025-09-12 10:27:22
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Intrinsically stable organic solar cells under high-intensity illumination
摘要： Organic photovoltaic cells are now approaching commercially viable efficiencies, particularly for applications that make use of their unique potential for flexibility and semitransparency1–3. However, their reliability remains a major concern, as even the most stable devices reported so far degrade within only a few years4–8. This has led to the belief that short operational lifetimes are an intrinsic disadvantage of devices that are fabricated using weakly bonded organic materials—an idea that persists despite the rapid growth and acceptance of organic light-emitting devices, which can achieve lifetimes of several million hours9. Here we study an extremely stable class of thermally evaporated single-junction organic photovoltaic cells. We accelerated the ageing process by exposing the packaged cells to white-light illumination intensities of up to 37 Suns. The cells maintained more than 87 per cent of their starting efficiency after exposure for more than 68 days. The degradation rate increases superlinearly with intensity, leading to an extrapolated intrinsic lifetime, T80, of more than 4.9 × 107 hours, where T80 is the time taken for the power conversion efficiency to decrease to 80 per cent of its initial value. This is equivalent to 27,000 years outdoors. Additionally, we subjected a second group of organic photovoltaic cells to 20 Suns of ultraviolet illumination (centred at 365 nanometres) for 848 hours, a dose that would take 1.7 × 104 hours (9.3 years) to accumulate outdoors. No efficiency loss was observed over the duration of the test. Overall, we find that organic solar cells packaged in an inert atmosphere can be extremely stable, which is promising for their future use as a practical energy-generation technology.
关键词： energy-generation technology,stability,organic photovoltaic cells,lifetime,high-intensity illumination
更新于2025-09-11 14:15:04
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1 cm <sup>2</sup> Organic Photovoltaic Cells for Indoor Application with over 20% Efficiency
摘要： Organic photovoltaic (OPV) technologies have the advantages of fabricating larger-area and light-weight solar panels on flexible substrates by low-cost roll-to-toll production. Recently, OPV cells have achieved many significant advances with power conversion efficiency (PCE) increasing rapidly. However, large-scale solar farms using OPV modules still face great challenges, such as device stability. Herein, the applications of OPV cells in indoor light environments are studied. Via optimizing the active layers to have a good match with the indoor light source, 1 cm2 OPV cells are fabricated and a top PCE of 22% under 1000 lux light-emitting diode (2700 K) illumination is demonstrated. In this work, the light intensities are measured carefully. Incorporated with the external quantum efficiency and photon flux spectrum, the integral current densities of the cells are calculated to confirm the reliability of the photovoltaic measurement. In addition, the devices show much better stability under continuous indoor light illumination. The results suggest that designing wide-bandgap active materials to meet the requirements for the indoor OPV cells has a great potential in achieving higher photovoltaic performance.
关键词： indoor application,power conversion efficiency,organic photovoltaic cells,photostability
更新于2025-09-11 14:15:04
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17% efficiency organic photovoltaic cell with superior processability
摘要： The development of organic photoactive materials, especially the new-emerging non-fullerene electron acceptors (NFAs), has enabled rapid progress in organic photovoltaic (OPV) cells in recent years. Although the power conversion efficiencies (PCEs) of the top-performance OPV cells have surpassed 16%, the devices are usually fabricated via a spin-coating method and are not suitable for large-area production. Here, we demonstrate that the fine-modification of the flexible side chains of NFAs can yield 17% PCE for OPV cells. More crucially, as the optimal NFA has a suitable solubility and thus a desirable morphology, the high efficiencies of spin-coated devices can be maintained when using the scalable blade-coating processing technology. Our results suggest that the optimization of the chemical structures of the OPV materials can improve the device performance. This has great significance in larger-area production technologies that provide important scientific insights for the commercialization of OPV cells.
关键词： non-fullerene acceptor,processability,power conversion efficiency,organic photovoltaic cells,scalable large-area production
更新于2025-09-11 14:15:04