Enhanced Photodetection Properties of Tellurium@Selenium Roll‐to‐Roll Nanotube Heterojunctions

Abstract

Non-layered tellurium (Te) is a promising material for applications in transistor and optoelectronic devices for its advantages in excellent intrinsic electronic and optoelectronic properties. However, the poor photodetection performance and relatively uncertain stability of tellurene under ambient conditions greatly limit the practical applications. In order to improve the performance of tellurene-based materials, Te@Se roll-to-roll nanotubes with different selenium (Se) contents synthesized by epitaxial growth of Se on Te nanotubes are, for the first time, employed to fabricate working electrodes for photoelectrochemical (PEC)-type broadband photodetection. They exhibit not only a preferably enhanced capacity for self-powered broadband photodetection but also significantly improved photocurrent density and stability in various aqueous environments (HCl, NaCl, and KOH solutions), compared to tellurene-based photodetectors. It is anticipated that the present work can open up new possibilities for high-performance tellurene-based optoelectronic devices.

Epitaxial Growth of Topological Insulators on Semiconductors (Bi2Se3/Te@Se) toward High‐Performance Photodetectors

“…The change in thickness reflects the successful synthesis of Te@Se NTs and the corresponding elements mapping images were depicted in Figure S1a of the Supporting Information. The shorter length of Te@Se NTs can be attributed to the vigorous stirring during the synthesis process, similar to the previously reported work . Figure c exhibits the SEM image of the prepared Bi 2 Se 3 /Te@Se, and it can be seen that lots of Bi 2 Se 3 NSs epitaxially grow on Te@Se NTs with the thickness range from 10 to 30 nm.…”

“…The P ph of 9.01 µA cm −2 can be obtained in 0.5 m HCl electrolyte which is higher than those of 0.5 m NaCl (1.68 µA cm −2 ) and NaOH (1.03 µA cm −2 ) electrolytes, respectively. The reasonable explanation can be ascribed to the different functionalities between Bi 2 Se 3 /Te@Se and the electrolytes . Compared with the other two electrolytes, HCl electrolyte possesses more proton H + which can be attached to the surface of Bi 2 Se 3 /Te@Se by transferring the positive charge, thus leading to the increased P ph .…”

“…Figure i revels the R ph as a function of light power density under different wavelengths and SL in 0.5 m NaOH electrolyte. It is worth noting that the PDs exhibit higher R ph than pristine Te and Te@Se‐based PDs, and the high R ph can be explained by the special surface Dirac cone of TI, which can effectively accelerate the transportation of photoinduced carriers 9b. It can be seen that the R ph gradually decreased with the increased wavelength and P λ , i.e., 2717.42 µA W −1 (400 nm, level I), 923.08 µA W −1 (400 nm, level VI), and 426.5 µA W −1 (700 nm, level VI), suggesting the Bi 2 Se 3 /Te@Se‐based PDs exhibit better performance in short wavelength and low P λ regimes.…”

“…It can be seen that the P ph first shows an increasing trend from 0.1 to 0.5 m NaOH electrolytes and then an obviously decrease is observed from 0.5 to 1.0 m NaOH electrolytes. The phenomenon can be ascribed to the decreased resistance ( R ) at electrode/electrolyte interface with the increased concentration of NaOH electrolytes (as shown in Figure c), possibly resulting from the undesired electrochemical reaction at high bias potential 21,28,30b. To further study the photoresponse behavior, various bias potentials were employed to evaluate the performance of the Bi 2 Se 3 /Te@Se‐based PDs in 0.5 m NaOH electrolyte as shown in Figure d.…”

“…When the PDs under light illumination, the O will detach from the surface of the Bi 2 Se 3 /Te@Se, resulting the reduced depletion region, especially in HCl electrolyte, which can accelerate the transmission of generated carriers and thus resulting the fast response time due to the reaction between H + and O 2 − (H+ + O 2 − →O 2 ) . On the contrary, in NaOH electrolyte, large amount of hydroxyl (OH − ) connected on the surface of Bi 2 Se 3 /Te@Se, which can suppress the absorption and desorption process of O and trap more valence electrons, resulting to the increased depletion region and suppressed transmission of carriers, thus the increased t res and t rec …”