Bio-inspired Carbon Hole Transporting Layer Derived from Aloe Vera Plant for Cost-Effective Fully Printable Mesoscopic Carbon Perovskite Solar Cells

Herein, we introduce a new ecofriendly naturally extracted cross-linked carbon nanoparticles as a hole transporting layer (C-HTL) prepared by an ancient Indian method for carbon based printable mesoscopic perovskite solar cells (C-PSCs), which is low-cost so far used for fully printable PSCs. The fabricated PSCs having Glass/FTO/mp-TiO₂/ZrO₂/perovskite/AV-C configuration exhibited current density (J_SC) of 20.50 ± 0.5 mAcm^–2, open circuit voltage (V_OC) of 0.965 ± 0.02 V and fill factor (FF) of 58 ± 2%, resulting in 12.3 ± 0.2% power conversion efficiency (PCE) for MAPbI₃ perovskite absorber. The aloe-vera processed carbon C-HTL based PSCs yields up to 12.50% power conversion efficiency and 15.80% efficiency for conventional spiro-MeOTAD based HTM. The air and moisture stability >1000 h at >45% relative humidity (RH) for cross-linked AV-C nanoparticle-based PSCs. This stability is very high compared to conventional spiro-MeOTAD HTM-based PSCs. The prepared carbon nanoparticles facilitate an excellent penetration of perovskite absorber in triple-layer-based scaffold, which enables a high-quality perovskite crystal and results in high PCE. This novel bio-inspired AV-C cross-linked nanoparticle-based natural carbon C-HTL is low-cost until date. We believe this technique would be suitable for and helpful toward fully printable and air-moisture-stable PSCs.