Carbon nanoparticle modified polyaniline for high performance light sensing

The binary response, considers a novel phenomenon which the current shifts between negative and positive during on/off light exposure, this response serves as a new and efficient approach to generate bidirectional output current directly and could be applied in binary light communication and other weak signal detection uses. This binary response obtained based on composites of polyaniline (PAni) and various weight percentages of carbon nanoparticles, CNPs of 50, 70 and 90 wt% which were synthesis onto Si substrates using ex-situ polymerization method to fabricate self-powered UV photodetector (SUP). PAni were synthesized via chemical oxidative polymerization of aniline monomer with ammonium persulfate as an oxidizing agent, whereas CNPs were prepared via hydrothermal method. The PAni-CNPs/Si composites were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, Scanning electron microscopy (SEM), and UV-Vis spectroscopy. The SEM images depicted that the CNPs dispersed homogeneously and buried inside PAni, more regular, rather rough with ballshape particles. The energy gap of PAni-50%CNPs film was 2.7 eV, and increases to 3.1 eV for concentration of 90 wt% of CNPs. The I-V curves were measured using Au electrodes onto PAni-CNPs/ Si active layer. The photo-detector that fabricated using PAni-70 wt% of CNPs shows a high sensitivity of 2.5 × 10 3 , high detectivity 1.42 × 10 11 Jones upon exposed to 390 nm UV light with rise and decay times of 0.23 s and 0.48 s, respectively at 0 V bias voltage. More interestingly, at a 0 V bias, the device achieves a binary response of positive and negative output current using an on/off light source of 520 nm.