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.