Fluorinated spacers: an effective strategy to tailor the optoelectronic properties and stability of metal-halide perovskites for photovoltaic applications

Metal halide perovskites or simply known as perovskites are organic-inorganic hybrid materials that have surpassed silicon-based photovoltaic (PV) technology in terms of power-conversion efficiency (PCE). However, low environmental stability remains the key challenge to be addressed before the industrial prospects of perovskite-based PV technology are met. Ligand engineering to control dimensionality and tune optoelectronic properties of perovskites is the most attractive way to endow them with environmental stability, passivate defects, manoeuvre exciton binding energy, enhance carrier mobility, and improve carrier extraction along with the integration of other desirable properties into the perovskites. In this regard, the exploration of fluorinated spacer cations for developing perovskites for PV applications seems highly imperative. This highlight presents state-of-the-art recent developments in the area of multi-dimensional perovskites, particularly focusing on developments in the area by exploring fluorinated spacers with regard to quasi-2D and 2D/3D-bilayer perovskites to offer solutions to the key issues of stability, exciton binding energy, charge carrier mobility, defect passivation, and any other issues pertaining to perovskites for application in PV devices. Also literature reports of fluorinated spacer manifested passivation that could tailor the optoelectronic properties of perovskites for PV applications are covered.