Extended wavelength and enhanced sensitivity of PbS colloidal quantum dots/Bi2Te3 photodetector by band alignment engineering

The tunable band gap of PbS colloidal quantum dots (CQDs) from ultraviolet (UV) to short-wave infrared (SWIR) bands provides many potential applications in optoelectronics. However, synthesis of large-sized CQDs that exhibit good stability and sensitivity for extended wavelength still remains a technological challenge. In this paper, a novel broadband photodetector based on small size PbS CQDs (with exciton absorption peak at 927 nm) and Bi2Te3 (with wide spectral sensitivity and high absorption) was devel-oped and studied. The device, which comprised of ITO/AZO/PbS CQDs/Bi2Te3/Al, provided an excellent band alignment that facilitated charge dissociation and transmission hence improving the device sensi-tivity. Furthermore, wavelength extension was also realized through the synergistic effect of these mate-rials, thus demonstrating broadband photodetection with high sensitivity. The heterostructure photodetector demonstrated good performance in the visible and near infrared ranges, especially at a wavelength of 1050 nm exhibiting a high responsivity (R) and detectivity (D*) of 161 A/W and 3.2 x 1013 Jones, respectively. In addition, the device exhibited excellent stability and reversibility after one month of storage without any encapsulation. This work lays a good foundation for the construction of the next generation of highly sensitive broadband CQDs photodetectors.& COPY; 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).