Comparative Study of Different Passivation Layers for n-i-p Perovskite Solar Cell for Indoor Applications

Indoor photovoltaics (IPV) plays a critical role in powering low-consumption devices within the rapidly growing Internet of Things (IoT). Perovskite solar cells (PSCs) have demonstrated impressive indoor power conversion efficiencies (iPCEs) exceeding 40%, driven by advancements in bulk and surface passivation techniques. These approaches mitigate trap states and recombination losses, significantly enhancing device efficiency and long-term stability. This study investigates the impact of surface passivation on the PSC performance by employing iodide-based passivators—phenethylammonium iodide (PEAI), octylammonium iodide (OAI), and guanidinium iodide (GUI)—alongside the Lewis base molecule 1,3-bis(diphenylphosphino)propane (DPPP), which, to the best of our knowledge, is introduced for the first time in n-i-p structured PSCs. SEM and XRD analyses revealed that DPPP-passivated samples exhibited superior morphological and structural stability after long-term ambient aging compared to other passivations. Under indoor 1000 Lx LED light illumination, the DPPP-passivated device achieved an iPCE of 33.14%, closely approaching the highest iPCE of 34.47% obtained with PEAI. Furthermore, the DPPP-passivated device demonstrated the highest stability under thermal stress (85°C) with a T80 of 753 h. This study highlights the impact of passivation layers on PSC performance and stability under low light conditions, paving the way for more effective strategies to advance perovskite materials in IPV applications.