Nickel sulfide thin films were prepared using electrodeposition on indium tin oxide-coated glass substrates. Films were characterized using X-ray diffraction for crystallographic analysis. The films were shown to be polycrystalline in nature with good uniformity. From scanning electron micrographs, the surface appeared to be comparatively granular with irregularly shaped grains. From optical analysis, the bandgap range was between 1.22 eV and 1.15 eV with an indirect bandgap nature. Mott-Schottky plot confirmed that the films were found to be n-type, and the semiconductor parameters of the film were derived.

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In this research, new donor–acceptor (D‐A) photovoltaic polymers were synthesized from dithieno[3,2‐b:2′,3′‐d]pyrrole electron donor derivatives, including N‐benzoyldithieno[3,2‐b:2′,3′‐d]pyrrole and N‐(4‐hexylbenzoyl)dithieno[3,2‐b:2′,3′‐d]pyrrole, in combination with the electron deficient unit 2,5‐bis(2‐ethylhexyl)‐3,6‐di(thiophen‐2‐yl)‐2,5‐dihydropyrrolo[3,4‐c]pyrrole‐1,4‐dione via direct (hetero)arylation polymerization. The D‐A conjugated polymers obtained were characterized via 1H NMR, gel permeation chromatography, Fourier transform infrared spectroscopy, DSC, XRD, photoluminescence and UV–visible methods. In addition, these D‐A polymers were used as activated layers in bilayer and bulk heterojunction structures for the fabrication of organic photovoltaic cells. © 2019 Society of Chemical Industry

Rubbing the donor in bilayer organic solar cells promotes the formation of adequate concentration gradients in the active layers. The improved charge collection yields large enhancements in the performances of fullerene and non-fullerene solar cells.