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In situ cyclized polyacrylonitrile (CPAN) is developed to replace n‐type metal oxide semiconductors (TiO2 or SnO2) as an electron selective layer (ESL) for highly efficient and stable n‐i‐p perovskite solar cells (PSCs). The CPAN layer is fabricated via facile in situ cyclization reaction of polyacrylonitrile (PAN) coated on a conducting glass substrate. The CPAN layer is robust and insoluble in common solvents, and possesses n‐type semiconductor properties with a high electron mobility of 4.13×10−3 cm2 V−1 s−1. With the CPAN as an ESL, the PSC affords a power conversion efficiency (PCE) of 23.12 %, which is the highest for the n‐i‐p PSCs with organic ESLs. Moreover, the device with the CPAN layer holds superior operational stability, maintaining over 90 % of their initial efficiency after 500 h continuous light soaking. These results confirm that the CPAN layer would be a desirable low‐cost and efficient ESL for n‐i‐p PSCs and other photoelectronic devices with high performance and stability. [ABSTRACT FROM AUTHOR]

Inorganic cesium lead iodide perovskite CsPbI3 is attracting great attention as a light absorber for single or multi‐junction photovoltaics due to its outstanding thermal stability and proper band gap. However, the device performance of CsPbI3‐based perovskite solar cells (PSCs) is limited by the unsatisfactory crystal quality and thus severe non‐radiative recombination. Here, vacuum‐assisted thermal annealing (VATA) is demonstrated as an effective approach for controlling the morphology and crystallinity of the CsPbI3 perovskite films formed from the precursors of PbI2, CsI, and dimethylammonium iodide (DMAI). By this method, a large‐area and high‐quality CsPbI3 film is obtained, exhibiting a much reduced trap‐state density with prolonged charge lifetime. Consequently, the solar cell efficiency is raised from 17.26 to 20.06 %, along with enhanced stability. The VATA would be an effective approach for fabricating high‐performance thin‐film CsPbI3 perovskite optoelectronics. [ABSTRACT FROM AUTHOR]

ABSTRACT Europium-containing cholesteric liquid crystalline polymers were graft copolymerized using poly(methylhydrogeno)siloxane, cholesteryl 4-(allyloxy)benzoate (M1), cholesteryl acrylate (M2), and a europium complexes monomer (M3). The chemical structures of the monomers were characterized by Fourier transform infrared and 1H-nuclear magnetic resonance. The mesomorphic properties and phase behavior were investigated by differential scanning calorimetry, thermo gravimetric analysis, polarizing optical microscopy, and X-ray diffraction. With an increase of europium complexes units in the polymers, the glass transition temperature ( Tg) did not change significantly; the isotropic temperature ( Ti) and mesophase temperature range (Δ T) decreased. All polymers showed typical cholesteric Grandjean textures, which was confirmed by X-ray diffraction. The temperatures at which 5% weight loss occurred ( Td) were greater than 300°C for the polymers. The introduction of europium complexes units did not change the liquid crystalline state of polymer systems; on the contrary, the polymers were enabled with the significant luminescent properties. With Eu3+ ion contents ranging between 0 and 1.5 mol %, luminescent intensity of polymers gradually increased and luminescent lifetimes were longer than 0.45 ms for the polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40866. [ABSTRACT FROM AUTHOR]