Promoting the hole extraction and interfacial performance with MOFs derived Co3O4@NC for efficient carbon-based perovskite solar cells

Carbon-based perovskite solar cells (C-PSCs) facilitate modularization and commercialization due to their excellent thermal stability and low cost. However, C-PSCs show the poor performance that charge carrier extraction by the carbon electrode alone is not as efficient as in the case of conventional hole transport materials (HTMs) based PSCs. In this work, an inorganic hole buffer layer of nitrogen-doped carbon/Co3O4 (Co3O4@NC) nanoparticles derived from MOFs is introduced to adjust energy alignment and passivate perovskite (PSK) grain boundaries (GBs). Moreover, a simple processing method on the Co3O4@NC nanoparticles manipulated by controllable ultraviolet/ozone (UVO) treatment is employed, to further improve the interfacial performance of MAPbI3/Co3O4@NC and reduce the hysteresis. Through interface engineering, it is found that Co3O4@NC inorganic hole buffer layer effectively promotes photo-generated charge separation and extraction, and suppresses charge recombination at the MAPbI3/Carbon electrode (CE) interface, resulting in improved photovoltaic performance. Consequently, the optimal C-PSCs without encapsulation achieved a maximum PCE of 14.63%, which is 22.3% more efficient than the pristine device (11.96%), and exhibited outstanding long-term stability.