Improved performance of carbon-based perovskite solar cells using a multi-walled carbon nanotubes/Zn(COO) nanocomposite.

Organohalide lead perovskites (PVKs) are among the most promising materials for creating high-efficiency and low-cost photovoltaic devices. However, challenges such as high trap densities, low crystallinity, and moisture sensitivity in perovskite films hinder the performance and stability of perovskite solar cells (PSCs). In this work, we address these limitations by incorporating a green, environmentally friendly nanocomposite multi-walled carbon nanotube/zinc oxalate (MWCNT/Zn(COO)₂) into the electron transport layer (ETL) to enhance the performance, stability, and cost-effectiveness of PSCs. The novel ETL, comprising mesoporous TiO₂ (mp-TiO₂) combined with the MWCNT/Zn(COO)₂ layer, demonstrated superior charge extraction and reduced charge recombination at the ETL/perovskite interface, leading to significant performance improvements. Furthermore, the PSCs demonstrated remarkable stability, retaining over 70% of their initial power conversion efficiency (PCE) after 70 days of storage in ambient conditions without encapsulation, a substantial improvement over conventional mp-TiO₂-based devices. Additionally, replacing expensive metals, such as gold (Au), with cost-effective carbon paste further reduces production costs, enhancing the economic viability of the devices. This work highlights the potential of the MWCNT/Zn(COO)₂ nanocomposite to enhance the efficiency and stability of PSCs, paving the way for greener and more cost-effective photovoltaic technologies.