Achieving Ultrafast Charge Transfer by Engineering Multiple Pn Junctions in 3D Hierarchical Cathodes Toward Photo-Chargeable Zinc-Organic Batteries.

Abstract

Photo-charging zinc ion batteries (PCZIBs) emerge as an innovative approach for the effective utilization and storage of solar energy. However, challenges originating from the suboptimal accessibility of photoexcited charges to electroactive sites severely restrict their practical applications. Herein, a facile methodology to balance light utilization and electrochemical performance by constructing multiple pn junctions in a 3D hierarchical PTCDA-SP/CuZnS photoelectrochemical cathode is reported. DFT calculations reveal that p-type CuZnS can adjust the local electronic environment of n-type PTCDA-SP, facilitating the formation of multiple pn junctions among the interface of this cathode. This unique nanostructure significantly promotes ultrafast charge transfer within 3ps and prevents other undesirable excited state decay pathways, as well as boosts ultrashort photo-response relaxation time less than 20s, resulting in high values of both photo current and voltage of 72.1µA cm-2 and 813mV cm-2 respectively. Additionally, all these carbonyls are responsible for photoelectrochemical Zn2+ storage cascade, ensuring significant improvements in reversible capacities (ca. 32%). This study describes a paradigm of building pn junction on 3D hierarchical cathodes to construct high-performance PCZIBs.