Wide Bandgap Donor can Offer High-Efficiency LED Indoor Organic Photovoltaic with Indium-Doped Zinc Oxide Electron Transport Layer

Abstract

Indoor organic photovoltaic (OPV) cells offer a compelling solution for powering diverse electronic devices integrated into the Internet of Things (IoT) network. They are prized for their robust power conversion efficiency (PCE), mechanical resilience, and ultra-thin nature. The recent surge in inverted-structure OPVs reflects their enhanced stability over conventional designs. Despite the advantage, their adaptation for indoor light utilization remains underexplored. Optimal selection of an electron transport layer (ETL) with precise energy band alignment is critical in this system. Herein, an inverted-structured OPV is fabricated utilizing PBDB-T as the wide bandgap donor, with a focus on enhancing its PCE under 1000 lx LED illumination through the doping of the zinc oxide- (ZnO-) based ETL with indium (In). The results indicate that the device utilizing undoped ZnO as the ETL achieves a peak PCE of 9.42% under these specified conditions. Conversely, the OPV utilizing In-doped ZnO as the ETL achieves a significantly higher PCE of 29.78% with 5 at% In, indicates the usefulness of ETL doping by In. This may be caused by the tuning of energy band alignment, improvement in electron mobility, and reduction in surface roughness of ZnO by In doping.