Deploying a Dipole Electric Field at the CsPbI₃ Perovskite/Carbon Interface for Enhancing Hole Extraction and Photovoltaic Performance

Carbon-based CsPbI₃ perovskite solar cells without hole transporter (C-PSCs) have achieved intense attention due to its simple device structure and high chemical stability. However, the severe interface energy loss at the CsPbI₃/carbon interface, attributed to the lower hole selectivity for inefficient charge separation, greatly limits device performance. Hence, dipole electric field (DEF) is deployed at the above interface to address the above issue by using a pole molecule, 4-trifluoromethyl-Phenylammonium iodide (CF₃-PAI), in which the ─NH₃ group anchors on the perovskite surface and the ─CF₃ group extends away from it and connects with carbon electrode. The DEF is proven to align with the built-in electric field, that is pointing toward carbon electrode, which well enhances hole selectivity and charge separation at the interface. Besides, CF₃-PAI molecules also serve as defect passivator for reducing trap state density, which further suppresses defect-induced non-radiative recombination. Consequently, the CsPbI₃ C-PSCs achieve an excellent efficiency of 18.33% with a high V_OC of 1.144 V for inorganic C-PSCs without hole transporter.