▎ 摘　　要

Excitonic solar cell (XSC) based on 2D materials has attracted widespread attention. Using first-principles calculations, XSC with high theoretical power conversion efficiency of around 21.3% formed by the combination of 2D cross-linked hexagonal boron nitride-graphene (BN-GR) and black phosphorene (BP) is rationally designed in this work. The good visible-light response, small conduction band offset, as well as the suitable band-gap (1.41 eV) of electron donor (BN-GR) lay the foundation for the excellent photoelectric conversion performance of the BN-GR/BP heterojunction. More importantly, it is found that the substrate (BN-GR) with different composition can drive uneven interlayer charge transfer in the BN-GR/BP heterojunction, resulting in the formation of an obvious electron-hole puddle at the heterojunction interface. This forms a lateral discharge functional optoelectronic device in addition to the vertical direction, which may even be a new development direction for electronic energy storage devices in the future.