Sustainable Manufacturing of Fully Printed Zn/ZnO/CNT Schottky Diodes on Kraft Paper

The escalating generation of electronic waste underscores the critical need for sustainable alternatives to conventional electronic technologies. Printed electronics emerge as a promising approach to address this issue by incorporating sustainable materials, implementing energy-efficient fabrication methods compatible with large-area manufacturing, and integrating end-of-life (EoL) strategies to minimize the environmental impact associated with waste management. In this work, we demonstrate fully printed Schottky diodes on kraft paper substrates fabricated using zinc (Zn) as a sustainable ohmic contact, zinc oxide (ZnO) nanoparticles as the semiconductor layer, and carbon nanotubes (CNTs) as the Schottky contact. The devices were manufactured using large area deposition processes at low-temperature and with vacuum-free printing techniques. The Cheung, Norde, and Mikhelashvili methods enabled the estimation of an effective Schottky barrier height of 0.75 ± 0.04 eV, a series resistance of 2.2 ± 1.5 kΩ, and a high ideality factor of 8.0 ± 1.4, which was corrected to 5.1 when it was voltage independent. These analyses also revealed the presence of trap states and the onset of a space-charge-limited current (SCLC) regime, with these electrical properties interpreted being considered and correlated with the morphological and structural characterizations. The diode exhibited a rectification ratio of (1.6 ± 1.2) × 10³ and, in a proof-of-concept demonstration, successfully performed half-wave rectification, underscoring its potential for low-power and low-frequency sustainable electronic circuits on paper. Finally, life cycle assessments (LCA) showed the adopted manufacturing approaches and materials provide a lower impact route for fabricating sustainable diodes.