The synthesis, XRD single‐crystal structure, powder XRD, and solid‐state fluorescence of two new DPA‐DPS‐EWG derivatives (DPA=diphenylamino, DPS=2,5‐diphenyl‐stilbene, EWG=electron‐withdrawing group, that is, carbaldehyde or dicyanovinylene, DCV) are described. Absorption and fluorescence maxima in solvents of various polarity show bathochromic shifts with respect to the parent DPA‐stilbene‐EWGs. The electronic coupling in dimers and potential twist elasticity of monomers were studied by density functional theory. Both polymorphs of the CHO derivative emit green fluorescence (527 and 550 nm) of moderate intensity (10 % and 5 %) in polycrystalline powder form. Moderate (5 %) red (672 nm) monomer‐like emission was also observed for the first polymorph of the DCV derivative, whereas more intense (32 %) infrared (733 nm) emission of the second polymorph was ascribed to the excimer fluorescence.
Deposition of the electron transport layer (ETL) is an important step in the manufacture of low‐cost, solution‐processed perovskite solar cells (PSCs). Thermal annealing processes account for a major part of the energy consumption involved in the fabrication of PSCs. The current paper presents a plasma‐based and highly convenient method (5 min, <60 °C) for the deposition of SnO2 films (PT‐SnO2) from a colloidal nanoparticle dispersion. A comparative evaluation of PT‐SnO2 films with those created by state‐of‐the‐art thermal annealing (30 min, 180 °C) (TA‐SnO2) is made herein. The key mechanism in the formation of the SnO2 layer is explained in relation to the evaporation of the dispersion medium. This comparison of PT‐SnO2 and TA‐SnO2 indicates a considerable difference in terms of energy consumption directly relevant to the low‐cost manufacture of PSCs. Photoluminescence analysis revealed no particular differences in the charge extraction of the two types of SnO2 films. The SnO2 films were subsequently employed as an ETL in planar n‐i‐p PSCs. Results revealed that the PSC resulting from PT‐SnO2 yielded an efficiency of 15.17%, similar to that of 15.91% corresponding to TA‐SnO2. In addition, the PSC fabricated on the PT‐SnO2 maintaining ≈80% of its initial performance after 21 days in ambient conditions.
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