Enhanced Performance and Stability of TiO2‐Nanoparticles‐Based Perovskite Solar Cells Employing a Cheap Polymeric Surface Modifier

Interface engineering of TiO2 nanoparticles (NPs)‐based perovskite solar cells (PVSCs) is often necessary to facilitate the extraction and transport of charge carriers. In this work, poly[{9,9‐bis[3′‐(N,N‐dimethyl)propyl]‐2,7‐fluorene}‐alt‐2,7‐(9,9‐dioctylfluorene)] (PFN) and polystyrene (PS) are demonstrated to be effective surface modifiers of the TiO2 NPs electron‐transporting layer in n‐i‐p PVSCs. The low‐cost insulating polymer PS performs better than the PFN conjugated polymer owing to its high film quality, low surface energy and insulating characteristics. A peak power conversion efficiency (PCE) of 15.09 % with an open‐circuit voltage (VOC) of 1.05 V and a PCE of 17.13 % with an ultrahigh VOC of 1.18 V is achieved with TiO2 NPs/PS‐based PVSCs using poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene] (MEH‐PPV) and spiro‐OMeTAD, respectively, as the hole‐transporting material. Cheap plastic in solar cells! TiO2 nanoparticles‐based perovskite solar cells (PVSCs) with a polystyrene (PS) interface modification layer and a poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene] (MEH‐PPV) hole‐transporting layer exhibit encouraging photovoltaic performances and stabilities. The use of a cheap plastic material in PVSCs would allow the fabrication of low‐cost PVSCs for commercial use