Interfacial modification via boronic acid functionalized self-assembled monolayers for efficient inverted polymer solar cells

In this study, we describe that the interface modification of blocking TiO2 (bl-TiO2) based polymer solar cells (PSCs) by self-assembled monolayer (SAM) can enhance the entire device performance. Three different fluorine-terminated boronic acid SAMs were applied to modify bl-TiO2 layer in inverted PSCs. It was determined that surface traps could be passivated and the energy level matching could be improved by introducing of fluorine-terminated boronic acid SAMs. The modifying with SAMs enhance the charge transport properties of bl-TiO2 layer. The morphological, optical and electrical characterizations were carried out for each solar cell fabricated. PSCs fabricated with 3,5-fluorophenylboronic acid (2-F) SAM modified bl-TiO2 resulted a power conversion efficiency (PCE) of 4.4%, which is a significant increase (~90%) compared with non-modified device. These underrated SAM molecules and their easy application to electronic devices provides an opportunity to investigate their applications. •Three different fluorine-terminated boronic acid SAMs were applied to modify bl-TiO2 layer in inverted PSCs.•The effect of boronic acid SAMs on polymer solar performance was investigated.•The power conversion efficiency increased from 2.3% to 4.4% after modification with SAM.•The enhancement on device performance is achieved by enhancing the charge transport properties of bl-TiO2 layer.