MAPbI3 Self-Recrystallization Induced Performance Improvement for Oxygen-Containing Functional Groups Decorated Carbon Nanotube-Based Perovskite Solar Cells

Abstract

Perovskite solar cells (PSCs) have attracted a lot of interest because of their high efficiency and low cost. However, in commercial applications, standard PSCs suffer from low stability of the cell components, including the hole transportation material (HTM). Owing to their characteristics of high chemical stability, hydrophobicity, and high conductivity, carbon nanotubes (CNTs) can be an alternative electrode to use to form HTM-free PSCs. Enhancing the interaction with perovskite is vital not only for photovoltaic performance but also for the stability of CNT-based PSCs. Herein, oxygen-containing functional groups are introduced into CNTs via acid treatment to enhance the chemical interactions with perovskite. The self-recrystallization ability of the perovskite material is discovered; its morphology shows significant improvement after long-term storage. Results show that acid oxidization of CNTs enable the self-recrystallization characteristics of MAPbI3-induced interfacial improvement, such that even with a dispersed initial photovoltaic performance, through storage in an ambient medium with relative humidity of 20–50%, the PSCs possess better interface contact, which results in lower charge transfer resistance, higher photovoltaic performance, and stability. As a result, PSCs with an initial power conversion efficiency range of 3.21–7.89% finally converge to within the range of 9.54–12.14% after long-term storage.