Self-doping in nanocrystals allows accessing higher quantum states. The electrons occupying the lowest energy state of the conduction band form a metastable state that is very sensitive to the electrostatic potential of the surface. Here, we demonstrate that the high charge sensitivity of the self-doped HgSe colloidal quantum dot solid can be used for sensing three different targets with different phases through self-doped HgSe nanocrystal/ZnO thin-film transistors: the environmental gases (CO 2 gas, NO gas, and H 2 S gas); mid-IR photon; and biothiol (l-cysteine) molecules. The self-doped quantum dot solid detects the targets through different mechanisms. The physisorption of the CO 2 gas and the NO gas molecules, and the mid-IR photodetection show reversible processes, whereas the chemisorption of l-cysteine biothiol and H 2 S gas molecules shows irreversible processes. Considering the quenching of mid-IR intraband photoluminescence of the HgSe colloidal quantum dot solid by the vibrational mode of the CO 2 gas molecule, sensing the CO 2 gas could be involved in the electronic-to-vibrational energy transfer. The target molecules are quantitatively analyzed, and the limits of detection for CO 2 and l-cysteine are 250 ppm and 10 nM, respectively, which are comparable to the performance of commercial detectors.
Bibliographical noteFunding Information:
*E-mail: email@example.com. ORCID Kwang Seob Jeong: 0000-0003-3246-7599 Funding This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, & Future Planning (NRF-2016R1C1B2013416) and LG Chem. Ltd. The author gratefully acknowledge the use of the facilities of the Korea Basic Science Institute (KBSI). Notes The authors declare no competing financial interest.
© 2019 American Chemical Society.
- TFT sensor
- gas sensor
- mid-IR photodetector
- probe-free biosensor
- self-doped nanocrystal
ASJC Scopus subject areas
- Materials Science(all)