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Recently, there has been significant improvement in the power conversion efficiency of non-fullerene organic solar cells, exceeding 19%. In this article, we have fabricated conventional sandwich structure of ITO/PEDOT:PSS/PM6:Y7/PDINO/Ag reaching efficiency up to 17.3% along with high generated current density of 30.60 mA/cm2 for the optimized devices. The thickness of PM6:Y7 layer has been varied to investigate the impact on the overall device behavior. The obtained results showed that the PCE has been enhanced by 15% upon reducing its thickness from 150 nm to 100 nm. Accordingly, current-voltage measurements and impedance spectroscopy analysis through capacitance-voltage, Mott-Schottky analysis and capacitance frequency under different illumination intensities were conducted to evaluate the behaviour of the charge recombination due to thickness variation of the PM6:Y7 photoactive layer.

Organic solar cells (OSCs) have reached an efficiency near 20%; however, their low long-term stability is the main limitation to their industrialization. In this work, we investigated the degradation of bulk heterojunction non-fullerene solar cells (NFA-OSCs) based on PM6:Y7 with an efficiency of 17.5%. The degradation analysis was carried out following the established ISOS-D-1 protocol under different degradation conditions: N-2 atmosphere (H2O < 0.1 ppm and O-2 < 0.1 ppm) and encapsulated devices and non-encapsulated devices exposed to ambient conditions (60 & PLUSMN; 5% relative humidity). The evolution of the current density-voltage (J-V) and impedance spectroscopy (IS) measurements were used to analyse the degradation process during 1000 h and its relationship with physical mechanisms. The degradation of encapsulated and non-encapsulated devices is mainly caused by the drop in the open circuit voltage (V-OC). For devices exposed to the N-2 atmosphere, the fill factor (FF) was the most affected parameter. The dependence of short circuit current density (J(SC)) versus light intensity study reveals that the efficiency of non-encapsulated devices decreases faster due to a higher bimolecular recombination degree. The devices under a N-2 atmosphere and those encapsulated showed T-80 lifetimes of 1000 h and 336 h, respectively, whereas the non-encapsulated devices have a short T-80 lifetime of less than 24 h. The analysis of the efficiency decay was used to identify the different degradation mechanisms (by diffused environmental water or oxygen or by intrinsic polymer chemical reactions) under different conditions. The degradation origin of the active layer and interlayers was investigated through impedance spectroscopy measurements.

A ternary strategy has been demonstrated as being an effective method to improve the power conversion efficiency (PCE); however, general rules for materials selection are not fully comprehended. Herein, nonfullerene acceptor ITIC-M and fullerene acceptor PC70BM possessing higher lowest unoccupied molecular orbital (LUMO) and good miscibility with nonfullerene acceptor Y7 are incorporated as third components in the state-of-the-art of PM6:Y7 binary blend. As a result, the device PCE for both ternary devices improves from 16.46% for binary host to 17.73% and 17.67% for ITIC-M- and PC70BM-based ternary devices, respectively. The higher LUMO of the guest acceptor can play multiple roles to elevate the open-circuit voltage such as reducing energy-loss and reverse saturation current, creating less-localized shallow trap sites along with suppressing charge recombination, and decreasing Urbach energy. Moreover, the good miscibility facilitates an alloy-like phase in acceptors domain for efficient exciton dissociation and electron transport, which leads to improved short-circuit current density and fill factor in ternary devices. The results provide a promising approach to realize high-performance ternary organic solar cells by synergizing the compatible third component with host acceptor.

The performance and industrial visibility of organic solar cells (OSCs) are greatly impacted by the functionality and stability of the interfacial layers. Many reported interface materials exhibited limitations in their fabrication temperature along with the operational stability toward the industrial up-scalability. In this work, a systematic analysis was conducted on the fresh and photo-aged-inverted non-fullerene organic solar cells (iNF-OSCs) with different structures of the electron transporting layers (ZnO, ZnO/PDINO, and PDINO), through studying their optical and electronic properties using external quantum efficiency measurements and impedance spectroscopy. Consequently, we presented PDINO as an efficient low temperature operation cathode interlayer for iNF-OSCs. Compared to the benchmark interface layers for i-OSCs such as ZnO, the PDINO interlayer used to replace the ZnO film, exhibiting a remarkable operational photostability. Where PDINO based iNF-OSCs demonstrated an extremely photostable behavior that is almost three times higher than the ZnO based devices under AM 1.5G (100 mW cm−2) continuous illumination conditions. This behavior might be attributed to the PDINO interlayer properties, which undergoes with no photochemical reaction with the contacted PM6:Y7 photo-active layer, avoiding the inescapable photocatalytic effect that is commonly obtained by the ZnO interlayer.

New experimental data are presented in this study for intermittent two and three-phase flows through horizontal pipelines involving air, water and polypropylene pellets of sizes ranging between 1 and 2 millimeters. Flow visualization and pressure measurements were performed and are explored in this work for intermittent flows. An automated image processing algorithm is developed to determine slug parameters of 59 flow conditions and compared with other measurements techniques. Correlations available in the literature for predicting slug frequency are tested with the new experimental data and curves of non-dimensional parameters are fitted to the data, the best fitting is obtained for the gas based Strouhal number against the input liquid or gas fraction. The influence of solid particles over the slug frequency is analyzed and reported. A decrease on the slug frequency is found when increasing solid concentrations. Finally, the influence of solid particles on the bubble length and velocity is investigated. A stronger influence of the gas flow rate on the velocity of the nose of the slug is observed for increasing solid concentration, together with more variability on the mean velocity. Also, longer bubbles are obtained with higher solid concentrations.

Finding an effective approach to suppress trap formation is a potential route for enhancing the performance of nonfullerene organic photovoltaic (NF-OPVs) devices. Here, an extraordinary short-circuit current density (JSC) value of 32.65 mA cm-2 is achieved, higher than the state-of-the art NF-OPVs reported, reaching a high power conversion efficiency (PCE) of 17.92%. This remarkable enhancement is exhibited through the fine-tuning of PEDOT:PSS/PM6:Y7 films and interface morphologies via applying the prethermal treatment approach (Pre-TT) to the devices, which exhibit JSC and PCE enhancement of 21% and 8%, respectively, compared to the pristine devices. Accordingly, the dependence of the JSC upon the Pre-TT approach through a range of morphological, optical, electrical, and advanced transient measurements is investigated. The Pre-TT-based films are found to possess optimal smooth blend morphology with better dispersity owing to reduced domain size. Moreover, the measurements show that the optimized treated devices present higher exciton dissociation probabilities and generation rate of the free charge carriers, showing an ideal balanced electron/hole mobility that reveals the JSC and PCE enhancement. Hence, Pre-TT approach provides a facile passivation strategy that reduces the trap state density of the blend film, improves interface charge transfer, allows balanced electron/hole mobility, and thus promotes device performance.

Morphological control of the layers within the bulk heterojunction organic photovoltaics (BHJ-OPVs) is a key feature that governs their performance. In the present work, we demonstrate that zinc oxide-ZnO-interlayers sprayed via the intermittent spray pyrolysis technique, employing a low-concentration precursor solution, can yield inverted BHJ-OPVs as efficient as the standard reported ones using the conventional laboratory-scale spin-coating technique. However, we record a pioneer stability behavior of the fabricated inverted fullerene organic photovoltaics (iF-OPVs) with various sprayed ZnO conditions. Thus, after optimizing the sprayed ZnO interfacial layer morphology for the inverted PTB7-Th:PC70BM devices, by carefully inspecting the interdependence between the sprayed ZnO thin film morphology and the figures of merit of the optimized iF-OPVs, we conducted a distinct analysis on the optical and electronic properties of the fresh and degraded devices using external quantum efficiency measurements and impedance spectroscopy. Hence, we showed that the most proper ZnO microstructural morphology was obtained by spraying 25 running cycles (25R). Remarkably, we observed that 25R-ZnO-based iF-OPV devices showed a stunning stability behavior and maintained 85% of their initial power conversion efficiency even after 16.7 months without encapsulation in a dry nitrogen glovebox, demonstrating an excellent shelf stability. Accordingly, this approach might facilitate the scalability of inverted OPVs for industrial production visibility.