Yew Hang Soo0000-0002-1945-9052Chai Yan Ng0000-0002-9019-4026Hieng Kiat Jun0000-0002-3987-4253Ng Soo Ai0000-0003-2551-7623Foo Wah Low0000-0003-2904-0172Rubina Bahar, CEng(MIMechE)CEng(MIMechE)Rubina Bahar2025-10-162025-10-162025-0510.1016/j.diamond.2025.112285https://dspace-cris.utar.edu.my/handle/123456789/11506The reliance on expensive metal electrodes has been a major barrier to the commercialization of perovskite solar cells (PSCs). Metal electrodes can only be deposited on PSCs through a batch-to-batch thermal evaporation process, which is incompatible with scalable fabrication processes essential for commercial production. On the other hand, carbon electrodes (CEs), specifically those made from graphite and carbon black, are low-cost and can be deposited using economical and facile methods such as doctor blading, screen-printing, and hot-pressing. Here, the feasibility of using a low-pressure hot isostatic pressing (HIP) to laminate carbon film onto a perovskite device stack to produce CE-based hole-transporting material-free (HTM-free) PSC was investigated. The carbon film was positioned on the caffeine-added methylammonium lead iodide (Caf-MAPbI3) perovskite film produced using a thermally enhanced vacuum-assisted solution process (VASP). The device was then vacuum-sealed in a thermoplastic bag and pressed in a HIP chamber under various pressures and temperatures for 10 min. The HIP process uniformly laminated the carbon film, promoting its seamless bonding with the Caf-MAPbI3 perovskite film at pressures of <= 10 MPa. A PSC achieved a champion power conversion efficiency (PCE) of 10.54 % with the optimized HIP pressure of 6 MPa and temperature of 125 degrees C.enLOW-TEMPERATUREINDUCED DEGRADATIONTHERMAL-STABILITYEFFICIENCYCONTACTGOLDThe reliance on expensive metal electrodes has been a major barrier to the commercialization of perovskite solar cells (PSCs). Metal electrodes can only be deposited on PSCs through a batch-to-batch thermal evaporation processwhich is incompatible with scalable fabrication processes essential for commercial production. On the other handcarbon electrodes (CEs)specifically those made from graphite and carbon blackare low-cost and can be deposited using economical and facile methods such as doctor bladingscreen-printingand hot-pressing. Herethe feasibility of using a low-pressure hot isostatic pressing (HIP) to laminate carbon film onto a perovskite device stack to produce CE-based hole-transporting material-free (HTM-free) PSC was investigated. The carbon film was positioned on the caffeine-added methylammonium lead iodide (Caf-MAPbI3) perovskite film produced using a thermally enhanced vacuum-assisted solution process (VASP). The device was then vacuum-sealed in a thermoplastic bag and pressed in a HIP chamber under various pressures and temperatures for 10 min. The HIP process uniformly laminated the carbon filmpromoting its seamless bonding with the Caf-MAPbI3 perovskite film at pressures of <= 10 MPa. A PSC achieved a champion power conversion efficiency (PCE) of 10.54 % with the optimized HIP pressure of 6 MPa and temperature of 125 degrees C.journal-article