G-Shield™: Low-Temperature Mechanochemical and Solvothermal Graphene-Encapsulated Copper (Cu@G) Paste for 100% Silver-Free Metallization of High-Efficiency Silicon Heterojunction and TOPCon Photovoltaics

G-Shield™ is a drop-in industrial photovoltaic metallization technology that substitutes 100% of silver (Ag) with commercial-grade sub-micron copper micro-flakes passivated by an atomically continuous 2–3 layer pristine graphene shell. Synthesized via a non-vacuum Low-Temperature Mechano-Chemical and Solvothermal (LT-MCS) route operating below 180°C, G-Shield™ prevents copper oxidation up to 380°C in ambient air and establishes an impenetrable steric barrier against deep-level copper diffusion into crystalline silicon. This preprint provides full physicochemical characterization, rheological screen-printing validation, M10 HJT cell electrical parameters (25.04% efficiency), IEC 61215 1,000h Damp Heat reliability, and a techno-economic analysis demonstrating a manufacturing cost of $23.30/kg, delivering over $64.6 million in annual savings for a 5 GW solar cell factory. Licença: GNU AGPLv3 para uso acadêmico/educacional. Licença Comercial Proprietária: uso comercial/industrial requer licenciamento formal. Cláusula de Value-Sharing (Royalties): qualquer uso comercial que gere faturamento confere ao autor Tiago Barbosa Dias Maciel (CPF 060.184.906-09) direito contratual a royalties de 2,5% a 5% sobre a receita líquida ou economia direta obtida. Chave GPG: EBED5C6C9D81481BBC93D28019A86EA7599F4BB4.