Inorganic–Organic Multicoating Layer Encapsulation of Formamidine Lead Halide Perovskite Quantum Dots for Lighting Applications

Pure-green formamidinium lead bromide (FAPbBr₃) perovskite quantum dots (PQDs) are particularly attractive for display and lighting applications. However, their inherent instability and processing challenges hinder their widespread application and commercialization. The instability of PQDs under exposure to light, heat, water, and oxygen is primarily attributed to their low formation energy, leading to phase transformations, agglomeration, and degradation, which negatively impact their optical properties. To address these challenges, this study proposes a dual-interface encapsulation strategy that integrates inorganic-organic synergy and covalent surface coupling into a single hierarchical framework. In this work, we present a cost-effective hierarchical multicoating strategy for stabilizing pure-green FAPbBr₃ PQDs using industrially accessible stabilization agents, namely SiO_<i>x</i> and dicyclopentanyl methacrylate (513M). Specifically, this research utilizes (3-aminopropyl) triethoxysilane (APTES) as a coupling agent ligand and tetraethoxysilane to uniformly coat the PQDs by SiO_<i>x</i>. Following this, 513M, a monomer, is radically polymerized on the surface of the SiO_<i>x</i>-coated PQDs to form a secondary shell layer. The initial coating enhances the PQDs' resistance to environmental factors, while the secondary layer (a hydrophobic polymer) further improves environmental stability without compromising the PQDs' structure during polymerization. The resulting FAPbBr₃@SiO_<i>x</i>@513M composite material, resulted in powder form, significantly improves the PQDs' durability against environmental conditions while maintaining excellent optical properties, including emission at ∼532 nm, a full width at half-maximum of ≤28 nm, and a photoluminescence quantum yield of >50%, demonstrating that robust environmental protection can be achieved without relying on record-high optical parameters or costly materials. Owing to its use of low-cost, scalable materials and pure-green emissive PQDs, this multicoating strategy offers a realistic pathway toward industrially viable, solid-state PQD materials for optoelectronic applications.