A Fully Starch-Based Platform Moving beyond Partial Eco-Friendliness for System-Level Biodegradable Organic Electronics

Eco-friendly, disposable organic electronics require device stacks composed of biodegradable components to ensure genuine environmental viability at end-of-life. Although bioderived materials have been investigated extensively, many reported systems remain “partially green,” as practical stacks often retain nondegradable elements or processing steps that are misaligned with eco-friendly disposal. Here, a solution-processed platform that moves beyond these limitations is demonstrated by utilizing starch as both the transparent substrate and the dielectric, strengthening comprehensive system-level eco-friendliness. The starch-based composite dielectric is fabricated via aqueous gelatinization incorporating a minimal amount of poly(vinyl alcohol) binder, glycerol plasticizer, and hexamethylenediamine (HMDA) cross-linker. Morphological analyses confirm that the combined incorporation of glycerol and HMDA markedly reduces surface roughness and suppresses drying-induced microcracks, yielding mechanically resilient and morphologically uniform dielectric films. Bottom-gate organic transistors exhibit well-defined p-type behavior with an on/off current ratio of 9.7 × 105, a stabilized threshold voltage of approximately −0.9 V, and a field-effect mobility of 0.21 cm2 V–1 s–1 (averaged over ≥10 devices per formulation). Biodegradation tests verify end-of-life compatibility, as starch-based devices undergo rapid structural disintegration within 7 days of soil burial. These results establish starch-based composites as a practical, scalable route toward truly disposable organic electronics.