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The solution‐processed electrode is key to the full‐solution‐processed organic solar cells (OSCs). Silver nanowires (AgNWs) are considered as an attractive solution‐processed electrode due to their low sheet resistance and high transmittance. However, the traditional "line‐plane" contact between AgNWs and the interface buffer layer is insufficient, resulting in the low performance of full‐solution‐processed OSCs. Herein, a bulk contact structure is reported between AgNWs and interface, formed by inserting the interface layer material, such as HMoOx (hydrogen molybdenum bronze) into the AgNWs networks. The extra HMoOx can be connected with the bottom interface buffer layer, forming a longitudinal network, and wrapping the AgNWs in the longitudinal interfacial layer. This bulk contact electrode‐interface structure increases the area of AgNWs/interface layers, promoting charge transfer and collection. Besides, the top‐injected method can enable the formation of a water‐based ink film on the top of the organic layer, as well as avoid solvent erosion between AgNWs and the interface layer. Based on the bulk contact electrode‐interface structure, this work realized high performance of 12.27% and 9.54% for 0.09 cm2 small‐area device and 10.8 cm2 full‐solution‐processed semitransparent mini‐module. These results provide a new idea for full‐solution‐processed OSCs preparation. [ABSTRACT FROM AUTHOR]

At present, the dominating electron transport material (ETL) and hole transport material (HTL) used in the state‐of‐the‐art perovskite solar cells (PSCs) are tin oxide and 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)‐9,9′‐spirobifluorene (Spiro‐OMeTAD). However, the surface hydroxyl groups of the SnO2 layer and the Li+ ions within the Spiro‐OMeTAD HTL layer generally cause surface charge recombination and Li+ migration, significantly reducing the devices' performance and stability. Here, a molecule bridging layer of 3,5‐bis(fluorosulfonyl)benzoic acid (FBA) is introduced onto the SnO2 surface, which provides appropriate surface energy, reduces interfacial traps, forms a better energy level alignment, and, most importantly, anchors (immobilizes) Li+ ions in the ETL, and consequently improves the device power conversion efficiency (PCE) up to 24.26% without hysteresis. Moreover, the device with the FBA passivation layer shows excellent moisture and operational stability, maintaining over 80% of the initial PCE after 1000 h under both aging conditions. The current work provides a comprehensive understanding of the influence of the extrinsic Li+ ion migration within the cell on the device's performance and stability, which helps design and fabricate high‐performance and hysteresis‐free PSCs. [ABSTRACT FROM AUTHOR]

Flexible organic solar cells (FOSCs) are one of the most promising power sources for aerospace aircraft due to their attractive advantages with high power-per-weight ratio and excellent mechanical flexibility. Understanding the performance and stability of high-performance FOSCs is essential for the further development of FOSCs for aerospace applications. In this paper, after systematic investigations on the performance of the state-of-the-art high-performance solar cells under thermal cycle and intensive UV irradiation conditions, in situ performance and stability tests of the solar cells in the 35 km stratospheric environment were carried out through a high-altitude balloon uploading. The encapsulated FOSCs with an area of 0.64 cm2 gave the highest power density of 15.26 mW/cm2 and an efficiency over 11%, corresponding to a power-per-weight ratio of over 3.32 kW/kg. More importantly, the cells showed stable power output during the 3-h continuous flight at 35 km and only 10% performance decay after return to the lab, suggesting promising stability of the FOSCs in the stratospheric environment. Flexible organic solar cell was launched to 35 km stratosphere through a high-altitude balloon, showing a high specific power ratio of 3.32 kW/kg and very good stability. [ABSTRACT FROM AUTHOR]

Drop‐on demand inkjet‐printing (IJP) is a deposition technique with promise in the context of fabricating large‐area organic solar cells (OSCs) because of its high material usage, direct‐pattern, and large‐area roll‐to‐roll printing compatibility. But its feature of drop‐to‐drop deposition during IJP makes the film's drying and phase separation process different from spin‐coating, and forms different nanophase separation and vertical phase separation morphology. In this work, the nanophase separation of the inkjet‐printed organic blend films is systematically studied at different substrate temperatures. The results reveal that increasing the substrate temperature can suppress excess molecules aggregation owing to the high drying speed, leading to improved exciton dissociation efficiency in the blend films. However, the quick drying process at high temperature also leads to a homogenous vertical phase separation, which is not ideal for charge collection. Instead of printing the mixture of donor and acceptor solution directly to form the bulk‐heterojunction structure, the polymer donor is printed on the top of the acceptor surface, a so‐called layer‐by‐layer inkjet printing (LBL‐IJP) process. By using this LBL‐IJP route, balanced nanoscale phase aggregation and gradient vertical phase separation morphology are achieved, which leads to a record power conversion efficiency of 13.09% for the OSCs with an inkjet‐printed active layer. [ABSTRACT FROM AUTHOR]

Transparent conductive electrode (TCE) is an essential part of modern optoelectronic devices. Silver nanowire (AgNW) is regarded as the most promising TCEs, owing to its balanced conductivity and transparency, and solution processability. The use of insulating polyvinyl pyrrolidone (PVP) surfactant limits the conductivity of the final AgNW networks. Herein, by introducing a small amount of deionized water into the AgNWs dispersion in isopropanol (IPA), the conductivity of the spray-coated AgNW electrode was significantly improved. Sheet resistance (Rs) of 27.0 Ω □−1 with transparency of 92% (at 550 nm) was obtained for the AgNW films spray coated from the AgNW ink with 20% water, which is much lower than the IPA-only AgNW film (120.9 Ω □−1 with similar transparency). Morphology analysis confirmed that water is able to wash PVP away from the AgNW surface and promote the formation of AgNW bundles, which increase the conductivity. The optimized AgNW ink was then used for perovskite and polymer solar cells. High power conversion efficiencies of 14.04% for perovskite solar cell and 6.44% for organic solar cells with averaged light transmittance of 21.7% and 33.12% are achieved, respectively, which are among the highest values for all solution-processed semi-transparent perovskite and polymer solar cells. [ABSTRACT FROM AUTHOR]

Stability is a big issue for the commercialization of perovskite solar cells. The degradation of perovskite solar cells is a complex physical–chemical process related to the photoactive layer, the interface layer, and the metal electrode. Zinc oxide (ZnO) is a popular material used as the electron‐transporting layer (ETL) in perovskite solar cells. A major problem of the ZnO ETL for perovskite solar cells is the thermal instability caused by the chemical reaction between ZnO and perovskite layer. Aiming to solve the degradation issue of perovskite solar cells a kind of ZnO nanoparticle that is chemically tailored with 2,3,4,5,6‐pentafluorobenzoyl chloride (ZnO@PFBC) is provided. Herein, the migration of halogen and zinc that takes responsibility for the thermal degradation of the p–i–n‐type perovskite solar cells through time of flight secondary‐ion mass spectrometry (ToF–SIMS) and X‐ray photoelectron spectroscopy (XPS) results is proved. Using ZnO@PFBC as a modifier of PC61BM, both the ion migration and the chemical reaction of ZnO and perovskite are suppressed. The thermal stability and long‐term illumination stability both in N2 and in ambient conditions are simultaneously improved, 75% of the initial efficiency remaining after 200 h of annealing at 85 °C. [ABSTRACT FROM AUTHOR]

The operational stability under continuous illumination and the shelf stability in air are all important for the real application of the organic solar cells (OSCs). In this work, we investigated the influence of the commonly used electron transporting layer (ETL), i. e. ZnO and polyethyleneimine (PEI) on the shelf and operational stability of the PM6:Y6 OSCs. Due to the photocatalysis effect of ZnO, the operational stability of ZnO ETL-based device is worse than the PEI ETL-based device. Due to the hygroscopicity of PEI, the shelf stability of the PEI ETL-based device is worse than the ZnO ETL-based device. By using a ZnO:PEI composite ETL, a balanced shelf and operational stability was obtained. For the inverted PM6: Y6 solar cells, the device could remain 80% and 60% of the initial efficiency after 1200 h continuous illumination, and storage in air for 1500 h, respectively. [Display omitted] • The influence of ETL on the shelf and operational stability of OSCs. • A strategy to achieve balanced shelf and operational stability of the PM6:Y6 device. • ZnO:PEI composite electron transporting layer was reported for high stable OSCs. • The poor and highly humidity -sensitive of the PEI-based device was found. [ABSTRACT FROM AUTHOR]

Vacuum-free fabrication is essential to realize large-scale production of organic solar cells. Blade-coating and printing are important solution-processing techniques to realize this idea. Preparation devices on large substrates is important for mass production; however, it is not easy to handle large substrates during fabrication procedures. In this work, we demonstrate a fabrication method for all-solution vacuum-free organic solar cells on an assembled glass substrates. Small pieces of glasses were assembled into a mosaic of larger total size for device fabrication. A gap-prefilling method was also developed to realize uniform thickness distribution. For the device with blade-coated ZnO electron transport layer, blade-coated active layer, spray-coated hole transport layer and spray-coated top electrode, power conversion efficiency of 4.19% is obtained. This showed that, by combining spray and blade coating, ultimate scale of the vacuum-free fabrication of OPV on glass substrate will not be limited by the substrate size itself, and can be scaled up to multi-meter by assembling the glasses into a mosaic. A method for all-solution vacuum-free organic solar cells on an assembled glass substrates were developed. Devices fabricated by blade-coating and spray-coating with power conversion efficiency of 4.19% was obtained. Image 1 • ‧A technique for all-solution vacuum-free organic solar cells on an assembled glass substrates is presented. • ‧A gap-prefilling method was also developed to realize uniform thickness distribution. • ‧Power conversion efficiency of 4.19% is obtained for the device with blade-coated PEDOT:PSS, blade-coated active layer, spray-coated hole transport layer and spray-coated top electrode. [ABSTRACT FROM AUTHOR]

With the rapid progress of organic solar cells (OSCs), improvement in the efficiency of large‐area flexible OSCs (>1 cm2) is crucial for real applications. However, the development of the large‐area flexible OSCs severely lags behind the growth of the small‐area OSCs, with the electrical loss due to the large sheet resistance of the electrode being a main reason. Herein, a high conductive and high transparent Ag/Cu composite grid with sheet resistance <1 Ω sq−1 and an average visible light transparency of 84% is produced as the transparent conducting electrode of flexible OSCs. Based on this Ag/Cu composite grid electrode, a high efficiency of 12.26% for 1 cm2 flexible OSCs is achieved. The performances of large‐area flexible OSCs also reach 7.79% (4 cm2) and 7.35% (9 cm2), respectively, which are much higher than those of the control devices with conventional flexible indium tin oxide electrodes. Surface planarization using highly conductive PEDOT:PSS and modification of the ZnO buffer layer by zirconium acetylacetonate (ZrAcac) are two necessary steps to achieve high performance. The flexible OSCs employing Ag/Cu grid have excellent mechanical bending resistance, maintaining high performance after bending at a radius of 2 mm. [ABSTRACT FROM AUTHOR]

Silver nanowires (Ag NWs) network is an excellent candidate as flexible transparent electrode applying in flexible perovskite solar cells, owing to their excellent electrical and optical properties. However, several problems including large surface roughness, chemical reaction between Ag and perovskite precursor, and migration of Ag limited the application in high performance perovskite solar cells. Aiming to solve these problems, the composite electrode combining the spray coated Ag nanowires and the low-temperature sol-gel zinc oxide was developed in this work. The optimized concentration and annealing temperature of sol-gel ZnO were 0.45 M and 150 °C. The introduction of zinc oxide with suitable concentration caused slight impact on the transmittance and sheet resistant of transparent composite electrode, and promoted mechanical and chemical stability in air relative to the pristine Ag NWs electrode. The use of the composite flexible electrode could decrease the surface roughness of the Ag NWs electrode, passivate the reaction of perovskite and silver electrode, and prevent the migration of Ag. As a consequence, the performance of the flexible device significantly improved from 9.51% to 13.12%. Under the AM 1.5G constant illumination, the optimization device has a remarkably improved stability than pristine device. This study demonstrates that spray Ag NWs as bottom electrode is suitable for flexible perovskite solar cells. Meanwhile, it's an effective method using sol-gel ZnO to construct composite electrode to promote the device performance and stability. Image 1 • Use sol-gel zinc oxide modification layer to solve the problem of Ag NWs transparent electrode in the perovskite solar cells. • The performance and stability of the device has been improved significantly. • The SIMS test proved that ZnO layer can constrain the diffusion of Ag during the aging. • The annealing temperature and precursor solution concentration of sol-gel ZnO has been optimized. [ABSTRACT FROM AUTHOR]