Laser generated WS2 quantum dots for effective charge transport in high-performance carbon-based perovskite solar cells

Abstract

Additive modification can be a meritorious method for performance enhancement of perovskite solar cells (PSCs). In this work, as a superior charge carrier transportation material, WS 2 quantum dots in anti-solvent are generated by pulsed laser irradiation and subsequently embedded in perovskite film to reduce the grain boundary barriers and accelerate charge transport via favorable band alignment, as can be proved by ultraviolet photoelectron spectroscopy (UPS). Besides, X-ray photoelectron spectroscopy (XPS) tests reveal the interaction of WS 2 quantum dots with Pb 2+ via Pb–S bonds, indicating the suppressed uncoordinated Pb 2+ trap states. Thus, the reduced defects and superior band alignment in PSCs will lead to the decreased charge recombination and excellent charge transport, which can improve the efficiency of PSCs. As a result, the highest power conversion efficiency (PCE) of 16.85% is obtained through WS 2 quantum dots modification with an optimum concentration of 0.1 mg/mL in anti-solvent, which is substantially promoted when compared with the pristine PSCs (13.27%). Moreover, the modified device sample can still keep 71% of the original PCE after 50-day conservation indoor with a humidity of 30–50%. This work can provide a novel fast and convenient method for WS 2 quantum dots fabrication and the potential applications in PSCs.