Hierarchical Nanostructures CuBi₂O₄ Integrated with Polyaniline Nanofibrous for Boosting Hole Extraction in Carbon-Based Perovskite Solar Cells

Toward commercialization of carbon-based perovskite solar cells (C-PSCs), it is crucial to innovatively design inorganic hole transport layer materials that excel in extracting and transporting charge carriers to promote their photoelectric conversion efficiency (PCE). In this work, a novel and high-connectivity CuBi₂O₄-polyaniline nanofibrous (CuBi₂O₄-PN) reticular structure is created by integrating CuBi₂O₄ hierarchical microspheres (CuBi₂O₄ MS) with polyaniline nanofibrous. The introduction of CuBi₂O₄-PN as a hole transport layer (HTL) notably enhances the contact quality of the devices and substantially reduces the surface defects of C-PSCs. In a comparative analysis under identical experimental conditions, MAPbI₃ devices incorporating CuBi₂O₄-PN HTL demonstrated a PCE of 14.79%, achieving a 44.3% increase over the reference device (10.25%). CuBi₂O₄-treated C-PSCs retained 89.9% of their original PCE after 45 days in storage, and they demonstrated improved stability over a longer time frame. This remarkable improvement in device performance can be attributed to the effective suppression of nonradiative recombination and the enhancement of the carrier transfer process in the device. Additionally, the unique interconnected reticular structure of CuBi₂O₄-PN provides efficient pathways for hole transfer, significantly contributing to the enhanced efficiency of the device.