Surface modification of c-TiO2 via different phenyl boronic acid SAMs for improved performance of inverted organic solar cells

Abstract

In this study, phenyl boronic acid (PBA) self-assembled monolayers (SAMs) with different terminal groups were introduced on c-TiO2, as interfacial modification layer in organic solar cells (OSCs) with inverted structure. The morphological, optical, electrical properties and the surface wettability of c-TiO2 layer were successfully tuned by SAMs modification. The all five SAMs introduced to device configuration improved the photovoltaic performances. The NO2-PBA SAM modified device exhibited a power conversion efficiency (PCE) of 3.4 % with a short-circuit current density of 9.68 mA cm-2, an open-circuit voltage of 0.59 V and fill factor of 48.46 %. More than 50 % enhancement on the PCE was achieved thanks to better ohmic contact and energy level alignment at the interface resulting improved charge collection. The surface properties can be changed by varying the terminal group of molecules, which can control the charge transport properties leading high shunt resistance and low series resistance. Our results showed that the PBA SAMs can be used as efficient interfacial modification layer for inverted OSCs.