Effect of Annealing Temperature on the Electrical Conductivity of Screen-Printed Prosopis Africana Carbon Char Paste for Electronics Applications

This study examines how annealing temperature influences the structural and electrical characteristics of screen-printed Prosopis Africana carbon char (PACC) and an organic binder paste intended for electronic applications. The material was subjected to controlled annealing at 300 °C, 400 °C, and 500 °C to evaluate the progressive changes in carbon ordering and conductive behavior. Raman spectroscopy revealed a clear temperature-dependent structural evolution, with the D-band to G-band intensity ratio (ID/IG) decreasing from 1.04 at 300 °C to 0.98 at 400 °C, and reaching 0.92 at 500 °C. This reflects the improvement in graphitic domain formation and reduction in structural disorder as the annealing temperature increases. These findings indicate that thermal treatment enhances the carbon char’s microstructural alignment, which is essential for improving charge transport pathways in printed electronic films. The electrical conductivity results exhibited a substantial increase with rising annealing temperature. The measured conductivity values progressed from 4.20 S/m at 300 °C to 40 S/m at 400 °C, culminating at 75 S/m when annealed at 500 °C. This enhancement is attributed to reduced internal resistance, improved particles interconnectivity, and the removal of residual organic components during thermal processing. The results confirm that optimizing annealing temperature is a critical step in tailoring the performance of bio-derived conductive pastes for low-cost and flexible electronic systems. The study demonstrates that Prosopis Africana carbon char, when properly thermally conditioned, can serve as a promising sustainable material capable of supporting reliable electrical performance in emerging green electronic technologies.