Tellurium nanostructures for optoelectronic applications

We report on fabrication of tellurium nanostructures (TN) that demonstrated promising applications in optoelectronics. Initially, TN were synthesized using a simple, one-step, room temperature, wet-chemical technique. During synthesis, the effect of number of parameters such as precursor concentration, its content, solvent ratios, their pH and reaction time has been investigated at a temperature ~ 120 °C. The obtained product was examined by UV–visible, IR spectroscopy, X-ray diffractometry, electron microscopy and energy-dispersive X-ray spectroscopic characterization techniques. Analysis revealed that TN have profound impact on the structure–property relationship through active and passive participation of Mo catalyst. During its initial growth stages, Te and O bonding gets influenced by Mo to form Mo–O–Te–O and Te–Mo–Te moieties, typically, at 6 h. This has implication onto the structural phase transformation of TN from Te-tube (TT) to Te-flake (TF) and then to TT again. Possible transformation mechanism is explained. Structurally, TN had hexagonal quasi-crystalline atomic arrangement with morphologically thin, transparent, bunched and close-caped TT characteristics having diameter 50–100 nm and length 0.8–2.1 µm, whereas TF is found to be thin, geometrically squared with area ~ 7 to 10 µm2. On their implementation for optoelectronic assessments, over the wavelength range 0.3–2.1 µm (power density ~ 100 mW/cm2), they showed peculiar luminescent and dark I–V responses. Relevant photocarrier dynamics has been revealed. TT, typically, showed 160% quantum efficiency, whereas TF ~ 40% is useful for optoelectronic devices. Details are presented. Graphical abstract Fabrication and optoelectronic assessments of tellurium nanostructure that showed time-dependent structural phase transformation from tube to flake to tube.