Phase‐Segregation Engineering of Binary Metal Selenide Heterojunctions on 3D N‐Doped Carbon Cubes: Boosting Carrier Transport via Electron‐Rich Field for High‐Performance Photovoltaics

ABSTRACT Facilitating rapid carrier transport through interfacial electron modulation and nanostructure construction is an effective strategy for designing efficient and stable carbon‐based electrodes, but it still poses significant challenges. Here, we propose a phase‐segregation engineering to prepare two binary metal selenide heterojunctions on 3D N‐doped carbon cubes, CoSe 2 /FeSe 2 @NDCC (CS/FS@NDCC) and NiSe 2 /FeSe 2 @NDCC (NS/FS@NDCC), by utilizing different metal‐based Prussian blue analogs as sacrificial templates. Based on the large specific surface area and abundant pores provided by the 3D nanocube structure, as well as the electron‐rich field effect generated by the self‐driven transfer of electrons at the inhomogeneous interfaces of binary selenides, the transport and extraction of carriers at the composite interface are significantly enhanced. When applied to the electrodes of carbon‐based perovskite solar cells (C‐PSCs) without a hole transport layer, CS/FS@NDCC and NS/FS@NDCC achieved power conversion efficiencies (PCEs) of 14.11% and 12.82%, respectively. Similarly, in Liquid‐junction solar cells, CS/FS@NDCC and NS/FS@NDCC demonstrated PCEs of 8.91% and 8.09%, respectively. This research provides both theoretical and experimental support for the development of highly efficient and stable carbon‐based heterojunction electrodes for new energy conversion devices.