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[Display omitted] • Heptafluorobutylammonium iodide (F7) was simply synthesized by reaction of hydroiodic acid. • F7-incorporated perovskite layer resulted in formed hydrophobic surface and reduced defect density. • Surface dipole by F7 was formed between perovskite and hole transporting layer, leading to promote charge-carrier extraction. • Photovoltaic performance was increased by incorporating F7 into perovskite layer. • The modified PSCs showed the excellent long-term stability at ambient conditions without encapsulation. Perovskite solar cells (PSCs) are a strong candidate for next-generation photovoltaics, but their long-term stability poses challenges for use as a future renewable energy source. In particular, ambient moisture causes detrimental effects on not only the stability but also performance of PSCs. Herein, alkylammonium salts with perfluorinated long alkyl chains are introduced to passivate the grain boundaries and form hydrophobic surfaces. The perfluorinated alkyl chain moiety introduced into the perovskite layer reduces defect density and suppresses nonradiative recombination, thereby enhancing carrier transport capability and achieving a power conversion efficiency (PCE) of 20.31 %. Given the hydrophobic effects of fluorinated compounds on PSCs, about 90 % of the initial PCE can be retained after 1,000 h of continuous operation under a relative humidity of ∼ 40 % without encapsulation. The proposed additive strategy thus enables long-term operational stability of PSCs under humid conditions. [ABSTRACT FROM AUTHOR]

This study describes a novel colorless polyimide window film using the concept of charge‐transfer complex (CTC) intensification. The resulting film has a tensile modulus of 8.4 GPa, total transmittance of ≈90%, and yellow index below 3. This is the best‐recorded balance between mechanical strength and optical properties for a highly flexible optical film. Additionally, the film exhibits a pencil hardness grade over 2H and folding reliability over 200,000 folding/unfolding cycles. These outstanding properties are attributed to the unique supramolecular structure, which features multiple hydrogen bonding and salt complexation interactions that lead to CTC intensification.

Random polythiophene polymers are characterized by the arbitrary sequences of monomeric units along polymer backbones. These untailored orientations generally result in the twisting of thiophene rings out of the conjugation planarity in addition to steric repulsions experienced among substituted alkyl chains. These tendencies have limited close polymer packing, which has been detrimental to charge transport in these moieties. To ameliorate charge transport in these classes of polymers, we make use of simple Stille coupling polymerization to synthesize highly random polythiophene polymers. We induced a positive microstructural change between polymer chains by attuning the ratio between alkyl-substituted and nonalkyl-substituted monomer units along the backbones. The optimized random polythiophene was found to have enhanced intermolecular interaction, increased size of crystallites, and stronger tendency to take edge orientation compared with both regiorandom and regioregular poly(3-hexylthiophene) polymers. Incorporation of the optimized random polythiophene as an active material in solid-state electrolyte-gated organic field-effect transistors exhibited better performance than the control device using regioregular poly(3-hexylthiophene), with a high hole mobility up to 4.52 cm2V–1s–1in ambient conditions.

Stretchability and areal coverage of active devices are critical design considerations of stretchable or wearable photovoltaics and photodetections where high areal coverages are required. However, simultaneously maximizing both properties in conventional island-bridge structures through traditional two-dimensional manufacturing processes is difficult due to their inherent trade-offs. Here, a 3D printer-based strategy to achieve extreme system stretchability and high areal coverage through combining fused deposition modeling (FDM) and flexible conductive nanocomposites is reported. Distinguished from typical approaches of using conductive filaments for FDM which have a flexibility dilemma and conductivity trade-offs, the proposed axiomatic approach to embed a two-dimensional silver nanowire percolation network into the surfaces of flexible 3D printed structures offers sufficient conductivity and deformability as well as additional benefits of electrical junction enhancement and encapsulation of silver nanowires. Kirigami/origami-pattern-guided three-dimensional arrangements of encapsulated interconnections provide efficient control over stretchability and areal coverage. The suggested process enables a perovskite solar module with an initial areal coverage of ∼97% to be electrically and mechanically reversible with 400% system stretchability and 25 000% interconnect stretchability under the 1000 cycle test, by folding down or hiding the origami-applied interconnects under the islands. This 3D printing strategy of potentially low cost, large size capabilities, and high speed is promising for highly flexible future energy conversion applications.

To realize a high-efficiency perovskite solar cell (PSC), it is critical to optimize the morphology of the perovskite film for a uniform and smooth finish with large grain size during film formation. Using a chemical compound as an additive to the precursor solution has recently been established as a promising method to control the morphology of the perovskite film. In this study, we propose a new method to achieve an improved morphology of the methylammonium lead iodide perovskite film by simultaneous addition of dimethyl sulfoxide (DMSO) and methoxyammonium salt (MeO) (dual additives). We demonstrated that an appropriate amount of the MeO additive helps the precursors form a stable intermediated PbI2-DMSO adduct during film formation and enlarges the perovskite grains by retarding the kinetics of conversion of the adduct to the perovskite. Furthermore, we experimentally observed that the optical band gaps and crystal structures of perovskite films are reasonably unaffected by the MeO additive because MeO is almost eliminated during annealing. By optimizing the amount of MeO, we achieved improved device performances of the PSCs with a high power conversion efficiency of 19.71% that is ∼15% higher than that obtained for the control device (17.15%).

The electron transport layer (ETL) is a key component of perovskite solar cells (PSCs) and must provide efficient electron extraction and collection while minimizing the charge recombination at interfaces in order to ensure high performance. Conventional bilayered TiO2ETLs fabricated by depositing compact TiO2(c-TiO2) and mesoporous TiO2(mp-TiO2) in sequence exhibit resistive losses due to the contact resistance at the c-TiO2/mp-TiO2interface and the series resistance arising from the intrinsically low conductivity of TiO2. Herein, to minimize such resistive losses, we developed a novel ETL consisting of an ultrathin c-TiO2layer hybridized with mp-TiO2, which is fabricated by performing one-step spin-coating of a mp-TiO2solution containing a small amount of titanium diisopropoxide bis(acetylacetonate) (TAA). By using electron microscopies and elemental mapping analysis, we establish that the optimal concentration of TAA produces an ultrathin blocking layer with a thickness of ∼3 nm and ensures that the mp-TiO2layer has a suitable porosity for efficient perovskite infiltration. We compare PSCs based on mesoscopic ETLs with and without compact layers to determine the role of the hole-blocking layer in their performances. The hybrid ETLs exhibit enhanced electron extraction and reduced charge recombination, resulting in better photovoltaic performances and reduced hysteresis of PSCs compared to those with conventional bilayered ETLs.