Carbon ZnO nanocomposite coats for improved optical and electronic characteristics of silicon photovoltaics

In this paper, zinc oxide (ZnO) and carbon-incorporated ZnO (C:ZnO) thin films were deposited on silicon (Si) substrates and investigated as potential surface passivation and antireflection layers for silicon-based photovoltaic applications. UV–visible absorption analysis demonstrated that carbon incorporation slightly narrowed the optical band gap while enhancing absorption within the visible spectrum, thereby promoting more efficient photon harvesting. The photoluminescence spectra of C:ZnO exhibited a pronounced suppression of defect-related emission peaks, evidencing a reduced density of non-radiative recombination centers. Transient photocurrent characterization revealed intensified and more stable photoresponses in C:ZnO relative to undoped ZnO, consistent with its improved optical activity. Moreover, photoconductance lifetime measurements indicated a substantial enhancement in carrier lifetime, increasing from 1.5 μs for bare Si to 49 μs for C:ZnO/Si, confirming superior surface passivation and interfacial quality resulting from carbon incorporation. These results highlight that carbon incorporation effectively improves the optical and electronic characteristics of ZnO, underscoring its potential for integration into high-efficiency silicon photovoltaic structures.