Molecular Order Induced Charge Transfer in a C<sub>60</sub>-Topological Insulator Moiré Heterostructure.
basic_science · Level V
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- Record sourced from PubMed, PMID 39803881.
- Also identified by DOI 10.1021/acs.nanolett.4c06294 and PMC identifier 11760159.
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Abstract
We synthesized and spectroscopically investigated monolayer (ML) C<sub>60</sub> on the topological insulator (TI) Bi<sub>4</sub>Te<sub>3</sub>. This C<sub>60</sub>/Bi<sub>4</sub>Te<sub>3</sub> heterostructure is characterized by an excellent translational order in a novel (4 × 4) C<sub>60</sub> superstructure on a (9 × 9) cell of Bi<sub>4</sub>Te<sub>3</sub>. Angle-resolved photoemission spectroscopy (ARPES) of C<sub>60</sub>/Bi<sub>4</sub>Te<sub>3</sub> reveals that ML C<sub>60</sub> accepts electrons from the TI at room temperature, but no charge transfer occurs at low temperatures. This temperature-dependent doping is further investigated by Raman spectroscopy, photoluminescence (PL), and calculations of C<sub>60</sub>/Bi<sub>4</sub>Te<sub>3</sub>. At low temperatures, Raman spectroscopy and PL show a dramatic intensity increase of the C<sub>60</sub>-related signal, suggesting a transition to a rotationally ordered state. Calculations explain the charge transfer by C<sub>60</sub> adsorption to Bi<sub>4</sub>Te<sub>3</sub> surface defects. The temperature dependence of the charge transfer is attributed to the orientational order of C<sub>60</sub>. The electron affinity of C<sub>60</sub> increases at low temperatures due to the freezing of the rotational motion.