Nonfullerene organic solar cells (OSCs) have achieved breakthrough with pushing the efficiency exceeding 17%. While this shed light on OSC commercialization, high-performance flexible OSCs should be pursued through solution manufacturing. Herein, we report a solution-processed flexible OSC based on a transparent conducting PEDOT:PSS anode doped with trifluoromethanesulfonic acid (CF3SO3H). Through a low-concentration and low-temperature CF3SO3H doping, the conducting polymer anodes exhibited a main sheet resistance of 35 Ω sq−1 (minimum value: 32 Ω sq−1), a raised work function (≈ 5.0 eV), a superior wettability, and a high electrical stability. The high work function minimized the energy level mismatch among the anodes, hole-transporting layers and electron-donors of the active layers, thereby leading to an enhanced carrier extraction. The solution-processed flexible OSCs yielded a record-high efficiency of 16.41% (maximum value: 16.61%). Besides, the flexible OSCs afforded the 1000 cyclic bending tests at the radius of 1.5 mm and the long-time thermal treatments at 85 °C, demonstrating a high flexibility and a good thermal stability.

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Inverted triiodine cesium lead (CsPbI3) perovskite solar cells (PSCs) are promising in photovoltaics owing to their ideal light absorption, non‐volatile active layer, and avoidance of fragile Spiro‐OmeTAD, especially as the top cell in tandem devices. However, they still exhibit far‐lagging efficiency, and must be processed in a strictly controlled environment due to water‐fearing CsPbI3. Here, a novel strategy to convert the harmful water erosions into an in situ stabilizer for efficient inverted CsPbI3 PSCs fabricated with a wide humidity operating window, is proposed. During air fabrication, maleic anhydride (MAAD) can react with water molecules in air to reduce moisture erosions, while the hydrolysis products (maleic acid, MAAC) control grains growth. After annealing, MAAC strongly binds to CsPbI3 grains as a shield to hamper phase transition and moisture penetration. A champion efficiency of 19.25% is obtained, which is the highest efficiency among the inverted inorganic PSCs. In parallel, the authors’ optimized devices present efficiency of 18.39% even fabricated in relative humidity 60% condition. Moreover, the stability against various ages is improved, and the optimized devices remain at 96.8% of its initial efficiency after maximum power point tracking at 65 °C for 850 h.

Future flexible organic solar cells (OSCs) require high efficiency, good flexibility and low fabrication cost. Here, we demonstrate a metal oxide-free flexible OSC based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) anodes with a...

Solution-based processing of two-dimensional (2D) materials provides the possibility of allowing these materials to be incorporated into large-area thin films, which can translate the interesting fundamental properties of 2D materials into available devices. Here, we report for the first time a novel chemical-welding method to achieve high-performance flexible n-type thermoelectric films using 2D semimetallic TiS nanosheets. We employ chemically exfoliated TiS nanosheets bridged with multivalent cationic metal Al to cross-link the nearby sheets during the film deposition process. We find that such a treatment can greatly enhance the stability of the film and can improve the power factor by simultaneously increasing the Seebeck coefficient and electrical conductivity. The resulting TiS nanosheet-based flexible film shows a room temperature power factor of ∼216.7 μW m K, which is among the highest chemically exfoliated 2D transition-metal dichalcogenide nanosheet-based films and comparable to the best flexible n-type thermoelectric films, to our knowledge, indicating its potential applications in wearable electronics.

We report efficient annealing-free solution-processed flexible organic solar cells (OSCs) integrated on a soft polyethylene substrate, with a high efficiency of 14.66% and a power-per-weight of 6.33 W g−1, close to that (15.73%) of thermally annealed control OSCs.

The chemical vapor deposition (CVD) method is a dry approach that can produce high quality crystals and thin films at large scale which can be easily adapted by industry. In this work, CVD technology is employed to grow high quality, large size all‐inorganic cesium lead bromide perovskite crystalline film for the first time. The obtained films have millimeter size crystalline domains with high phase purity. The growth kinetics are examined in detail by optical microscopy and X‐ray diffraction. The deposition rate and growth temperature are found to be the key parameters allowing to achieve large scale crystal growth. The large crystalline grains exhibit exceptional optical properties including negligible Stokes shift and uniform photoluminescence over a large scale. This suggests a high degree of crystallinity free from internal strain or defects. A lateral diode within one large crystalline grain is further fabricated and significant photo‐generated voltage and short circuit current are observed, suggesting highly efficient carrier transport and collections without scattering within the grain. This demonstration suggests that the CVD grown all‐inorganic perovskite thin films enable a promising fabrication route suitable for photovoltaic or photo‐detector applications.

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