Enhancing the photovoltaic performance of perovskite solar cells via ferrocene dicarboxylic acid-doped-poly(9-vinylcarbazole) passivation

The non-radiative recombination energy losses at perovskite absorber/transport layer interfaces are one of primary causes of the limited power conversion efficiency of perovskite solar cells (PSCs). Here we report an effective method to make smaller the defect-assisted non-radiative electron–hole recombination via incorporating a mixture of ferrocene dicarboxylic acid (FDA) and p-type poly(9-vinylcarbazole) (PVC) at the absorber/hole transport layer (HTL) interface. Our findings demonstrate that incorporating FDA-PVC significantly improves the overall performance of the PSC devices by enhancing the crystalline quality of the absorber layer, passivating defects, suppressing trap-state density, reducing non-radiative recombination, and promoting hole extraction efficiency. Additionally, the FDA-PVC layer serves as a protective layer, increasing the environmental stability of the devices. The FDA-PVC-treated PSCs achieved a rise in the efficiency from 16.28 to 20.67%. The efficiency enhancement is attributed to the cooperative impacts of surface imperfection passivation and interfacial energy barrier reduction. Moreover, the corresponding unsealed cell maintained 78% of the initial efficiency after 500 h of aging under high humid conditions (50–65% RH).