Layered semiconductor tungsten disulfide: photoactive material in bulk heterojunction solar cells

We demonstrate 2D-layered semiconductor tungsten disulfide (WS2) nanoflakes as an efficient photoactive material in bulk heterojunction (BHJ) solar cells. WS2 nanoflakes-coated titanium dioxide (TiO2) nanoparticles layer serves as the electron acceptor with poly(3-hexylthiophene) (P3HT) as the hole conductor. The UV–visible spectroscopic measurement yields an optical bandgap of ∼1.7 eV for the WS2 nanoflakes, confirming the presence of mixed monolayer/few-layers stack. Raman spectra of the WS2-coated TiO2 show a dominant peak at 140 cm−1 for anatase TiO2, whereas peaks at 350 cm−1 (in-plane vibration mode) and 420 cm−1 (out-of-plane vibration mode) denote the signature of WS2 nanoflakes. Photovoltaic performance, electron transport, and recombination at TiO2/WS2/P3HT interfaces are explored through trap-assisted Shockley–Read–Hall model to elucidate WS2 as a potential material candidate for efficient solar energy harvesting.

Graphical AbstractBulk heterojunction solar cells employing 2D-layered semiconductor WS2 as a photoactive material are presented. Photovoltaic performance, electron transport, and recombination at TiO2/WS2/P3HT interfaces are explored through trap-assisted Shockley–Read–Hall model to elucidate WS2 as a potential material candidate for efficient solar energy harvesting.Figure optionsDownload as PowerPoint slideHighlights
► Layered semiconductor as a photoactive material for solar energy harvesting.
► With variable optical bandgap, WS2 enables broad-spectrum photon absorption.
► Photon absorption of WS2 demonstrated in a wavelength region of 350 nm–750 nm.
► Transport and recombination at TiO2/WS2/P3HT interfaces impedes device performance.