Observation of Ultrahigh Photoconductivity in DNA-MoS₂ Nano-Biocomposite

A nano-biocomposite film with ultrahigh photoconductivity remains elusive and critical for bio-optoelectronic applications. A uniform, well-connected, high-concentration nanomaterial network in the biological matrix remains challenging to achieve high photoconductivity. Wafer-scale continuous nano-biocomposite film without surface deformations and cracks plays another major obstacle. Here ultrahigh photoconductivity is observed in deoxyribonucleic acid-molybdenum disulfide (DNA-MoS₂) nano-biocomposite film by incorporating a high-concentration, well-percolated, and uniform MoS₂ network in the ss-DNA matrix. This is achieved by utilizing DNA-MoS₂ hydrogel formation, which results in crack-free, wafer-scale DNA-MoS₂ nano-biocomposite films. Ultra-high photocurrent (5.5 mA at 1 V) with a record-high on/off ratio (1.3 × 10⁶) is observed, five orders of magnitude higher than conventional biomaterials (≈10¹) reported so far. The incorporation of the Wely semimetal (Bismuth) as an electrical contact exhibits ultrahigh photoresponsivity (2.6 × 10⁵ A W^-1). Such high photoconductivity in DNA-MoS₂ nano-biocomposite could bridge the gap between biology, electronics, and optics for innovative biomedicine, bioengineering, and neuroscience applications.