A multifunctional polymer surface modifier enables efficient and stable photoelectrochemical operations of organic photoanodes

Abstract

We introduce ethoxylated polyethylenimine (PEIE) as a polymer surface modifier for the electron transport layer (ETL) of organic photoanodes to improve photoelectrochemical performance and operational stability. Using SnO₂ as the ETL, the organic photoanode achieves a superior photocurrent density of 15.18 mA cm⁻² at 1.23 V_RHE during sulfite oxidation, significantly outperforming its ZnO based counterpart (8.51 mA cm⁻²). Notably, PEIE modification on SnO₂ induces a pronounced cathodic shift in the onset potential from 0.49 to 0.23 V_RHE. Spectroscopic analyses reveal that PEIE facilitates enhanced charge extraction and reduces interfacial recombination under photoelectrochemical operation. Futhermore, PEIE-modified SnO₂ effectively prevents delamination of the organic bulk-heterojunction films from metal oxide substrates, retaining 90% of the initial photocurrent after 30 minutes of continuous sulfite oxidation with direct organic/electrolyte contact. These findings highlight the potential of this multifunctional polymer surface modifier to advance durable and efficient organic photoelectrochemical devices for oxidation catalysis.