Swift advancement in perovskite solar cell (PSCs) efficiency poses a challenge in maintaining a balance among sustainability, efficiency, and cost for competitive commercialization. Ongoing research is dedicated to effectively addressing these challenges. Traditional PSCs rely on expensive and unstable hole-transporting materials (HTMs) and noble metal electrodes, leading to poor device stability. To overcome these challenges, this study introduces unencapsulated planar HTM-free carbon electrode-based PSCs (C-PSCs) created through an entirely low-temperature process (< 160°C) in ambient atmospheric conditions. The approach emphasizes simplicity and cost-effectiveness, incorporating a single electron transporting layer and a one-step perovskite layer (Cs_0.17FA_0.83Pb(I_0.83Br_0.17)₃) fabrication. Carbon films, prepared using an ethanol solvent interlacing method and heat-press transfer, serve as both hole transport layers (HTL) and electrodes. This simplified architecture leverages the properties of carbon materials, achieving the highest power conversion efficiency (PCE) of 11.09% and exceptional shelf-life stability exceeding 2 years (~20,000 hours) without encapsulation. Remarkably, thermal and humidity stability tests under accelerated aging conditions (85% relative humidity, 85°C) demonstrated an average 90% efficiency drop after 100 hours. Furthermore, the scalability of the technique is demonstrated in 1.00 cm² planar HTM-free C-PSCs on recycled FTO/TiO₂-NPs substrates, exhibiting remarkable performance under both 1 sun and LED illuminations. This approach lowers production costs, making PSCs more renewable and sustainable, paving the way for cost-effective and eco-friendly commercialized PSCs.

Carbon Electrode, HTM-free, Low-temperature, Perovskite Solar Cells, Stability, Sustainability