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Metal halide perovskite solar cell (PSC) has successfully distinguished itself in optoelectronic field by virtue of the sharp rise in power conversion efficiency over the past decade. The remarkable efficiency breakthrough at such a fast speed can be mainly attributed to the comprehensive study on film deposition techniques, especially the effective management of surface and interfacial defects in recent works. Herein, we summarized the current trends in performance enhancement for PSCs, with a focus on the generally applicable strategies in high-performance works, involving deposition methods, compositional engineering, additive engineering, crystallization manipulation, charge transport material selection, interfacial passivation, optical coupling effect and constructing tandem solar cells. Promising directions and perspectives are also provided.

A synthetic route was developed to introduce an electron accepting unit, 2,5-di(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4-dione (DPP), into the main chain of regioregular poly(3-hexylthiophene) (P3HT) at a low concentration (ca. 4.5 mol % in monomer ratio), in order to lower the optical bandgap and simultaneously retain high hole mobility in P3HT. First, regioregular oligo(3-hexylthiophene) (O3HT), a macromonomer with a narrow polydispersity, was synthesized by Ni-catalyzed Grignard metathesis polymerization and subsequent stannylation of the chain ends. The copolymer was then synthesized by Stille coupling between the DPP unit and the macromonomer. The copolymer exhibits an extended absorption shoulder up to 750 nm, in addition to the original absorption of P3HT, as a result of intramolecular charge transfer. X-ray diffraction, field-effect transistor measurements, and UV–vis absorption of the polymer films showed that the crystal structure and high hole mobility were retained, owing to the regioregular O3HT blocks. Organic solar cells based on the copolymer and [6,6]-phenyl-C61-butyric acid methyl ester showed a broad photocurrent response of up to 900 nm and a power conversion efficiency of 2.07% without deterioration of the fill factor. [ABSTRACT FROM AUTHOR]

A novel hexagonal two-dimensional ZnO nanosheet thin film was successfully synthesized on an aluminum substrate by a simple wet-chemical approach, which exhibited very strong orange emission. It was concluded that ZnO nanosheets were induced to grow along 〈−1 1 0 0〉directions by the boehmite layer formed on the surface of the aluminum substrate. In addition, the orange photoluminescence of the ZnO nanosheet film has been discussed in detail. [ABSTRACT FROM AUTHOR]