Lateral organic-inorganic hybrid Vis-NIR photodetectors based on GaN nanowires promoting photogenerated carriers transfer

Abstract

The narrow bandgap of the low-energy near-infrared (NIR) polymer would lead to overlap between adjacent energy levels, which is a major barrier to the preparation of Vis-NIR polymer bulk heterojunction (BHJ) photodetectors with small responsivity and photocurrent. In this study, a high-performance lateral inorganic-organic hybrid photodetector was constructed to eliminate this barrier by combining GaN nanowires (GaN-NWs) with PDPP3T:PC61BM-based BHJ. In stage one, high-quality GaN-NWs were synthesized by the catalyst-free CVD method. The mechanism for controlling GaN-NWs morphology by adjusting the NH3 flow rate was revealed. In stage two, the GaN-NWs with large electron mobility were used to accelerate the transfer of photogenerated carriers in the BHJ layer. Finally, compared with the BHJ device, the BHJ/GaN device demonstrated obvious improvements in responsivity and photocurrent at the wavelength between 400 and 1000 nm. The responsivity and photocurrent increased over 20-fold at the NIR band of 800–900 nm. Besides, owing to the energy level gradient effect, the BHJ/GaN device has a response speed of 7.8/<5.0 ms, which increases over three orders of magnitude than that of the GaN-NWs-based device (tr/tf: 7.1/10.9 s). Therefore, the novel device structure proposed in this work holds great potential for preparing high-performance Vis-NIR photodetectors.