Lead-Free Carbon-Based Nanotubes in Perovskite Solar Cells: A Comprehensive Review of Recent Developments and Future Directions

Abstract

Background: Perovskite solar cells (PSCs) are the third-generation solar cell technology with a high power conversion efficiency and low cost of fabrication. Nevertheless, the presence of poisonous lead elements and their lousy long-term performance limit their practical uses. Recently, the combination of lead-free materials with carbon-based nanotubes (CNTs) has emerged as an attractive prospect to overcome these challenges and provide insights in sustainable and viable solar devices. Aim: In this review will be given an overview of the most recent advances in the use of lead-free carbon-based NTs in relation to PSCs, covering the main achievements and findings in the period of 2021-2025. The review also discusses the challenges facing the field and future directions. Method: The study was a systematic literature review in accordance with PRISMA guidelines. The search of databases such as Scopus, Web of Science, ScienceDirect was used to obtained peer-reviewed articles published during 2021–2025. The selection criteria for these studies were experimental studies performed on CNTs in leaf-free PSCs and dealing with efficiency improvement, durability, and fabrication process. The contents of each included study were stripped and tabulated and analyzed thematically.Results: It is found that the CNTs significantly improve charge mobility combined with the suppression of recombination losses and better thermal and moisture stability in lead-free PSCs. When nitrogen-doped and functionalized CNTs were integrated into tin- and bismuth-based perovskites, PCEs of 13–17% were obtained along with enhanced operational stability. Deposition methods including spray coating and vacuum filtration supported large-scale processing of the device and uniform performance. Conclusion: Carbon-based nanomaterials are a promising candidate to enhance the power-conversion efficiency, stability of lead-free PSCs. Further development of materials and industrial-scale process optimization will be necessary as the materials advance toward commercial application.

Keywords: Lead-free perovskite solar cells, carbon nanotubes, charge transport, energy materials, sustainable photovoltaics, nanotechnology.