Carbon dopants carriers facilitators as agents for improving hole extraction efficiency of cobalt tetraoxide nanoparticles employed in fabrication of photodetectors

(CH₃NH₃)₃Bi₂I₉ perovskites have attracted enormous attention due to their lower toxic and more stable nature than CH₃NH₃PbI₃ counterparts. However, higher bandgap and lower carrier mobility hinder the application of (CH₃NH₃)₃Bi₂I₉ in optoelectronics. Hence, we employed carbon doping of Co₃O₄ hole extractors to reduce the bandgap of (CH₃NH₃)₃Bi₂I₉, minimize non – radiative recombination rate and improve surface morphology of the (CH₃NH₃)₃Bi₂I₉ particles. Consequently, photodetectors based on carbon-doped Co₃O₄ display reduced internal resistance, high photocurrent and low dark current values. The fabricated photodetectors display high responsivity (1.56 × 10⁶ μA/W), high detectivity (5.74 × 10¹² Jones), high sensitivity (8.23 × 10³) and fast optical switching times (< 10 ms) values under device testing conditions of 2.0 V bias voltage, 10 mW/cm² power intensity of solar illumination and ambient room conditions. The linearity and stability of the photodetectors over wide range of light intensities and 100 optical switching cycles were also demonstrated respectively.