Engineering the energy bandgap of lead cobalt sulfide quantum dots for visible light optoelectronics

The energy bandgap of ternary alloyed lead cobalt sulfide quantum dots has been engineered for visible light optoelectronic applications. Ternary Pb_0.8Co_0.2S QDs were synthesized in situ onto TiO₂ electrodes using a sub-sequential chemical bath deposition method up to 7 times. The surface morphology of the prepared alloyed Pb_0.8Co_0.2S QDs photoanodes was characterized using a transmission electron microscope. The X-ray diffraction technique was used to study the structural properties of the prepared alloyed photoanodes. The optical properties were characterized using a UV-visible-NIR spectrophotometer in the visible region range. The absorption of the prepared photoanodes increases as the no. of deposition times rises up to 7. Besides, the energy bandgap of the alloyed photoanodes is red-shifted from 3.15 eV (393 nm) to 1.68 eV (738 nm). These bandgap red shifts are mainly attributed to the quantum confinement effect. Based on optical properties measurements, the prepared ternary alloyed QDs could be utilized effectively in visible light optoelectronic applications.